MyMedR

Displaying publications 1 - 20 of 63 in total

Abstract:

Sort:

Fulltext Dynamic Optimization for Controller Tuning with Embedded Safety and Response Quality Measures

Ahamad, I.S., Choong, T.S.Y., Yunus, R., Chuah, T.G., Vassiliadis, V.S.

Pertanika Journal of Science & Technology, 2011;19(2):397-414.
MyJurnal

Controller tuning is needed to select the optimum response for the controlled process. This work presents a new tuning procedure of PID controllers with safety and response quality measures on a non-linear process model by optimization procedure, with a demonstration of two tanks in series. The model was developed to include safety constraints in the form of path constraints. The model was then solved with a new optimization solver, NLPOPT1, which uses a primal-dual interior point method with a novel non-monotone line search procedure with discretized penalty parameters. This procedure generated a grid of optimal PID tuning parameters for various switching of steadystates to be used as apredictor of PID tunings for arbitrary transitions. The interpolation of tuning parameters between the available parameters was found to be capable to produce state profiles with no violation on the safety measures, while maintaining the quality of the solution with the final set points targeted achievable.
Fulltext Effect of supercritical fluid density on nanoencapsulated drug particle size using the supercritical antisolvent method

Kalani M, Yunus R

Int J Nanomedicine, 2012;7:2165-72.
PMID: 22619552 DOI: 10.2147/IJN.S29805

The reported work demonstrates and discusses the effect of supercritical fluid density (pressure and temperature of supercritical fluid carbon dioxide) on particle size and distribution using the supercritical antisolvent (SAS) method in the purpose of drug encapsulation. In this study, paracetamol was encapsulated inside L-polylactic acid, a semicrystalline polymer, with different process parameters, including pressure and temperature, using the SAS process. The morphology and particle size of the prepared nanoparticles were determined by scanning electron microscopy and transmission electron microscopy. The results revealed that increasing temperature enhanced mean particle size due to the plasticizing effect. Furthermore, increasing pressure enhanced molecular interaction and solubility; thus, particle size was reduced. Transmission electron microscopy images defined the internal structure of nanoparticles. Thermal characteristics of nanoparticles were also investigated via differential scanning calorimetry. Furthermore, X-ray diffraction pattern revealed the changes in crystallinity structure during the SAS process. In vitro drug release analysis determined the sustained release of paracetamol in over 4 weeks.
Fulltext Wind characteristics and outdoor thermal comfort assessment in East Malaysia

Hanipah, M.H., Abdullah, A.H., Che Sidek, N.A., Yunus, R., Nagapan, S., Yassin, M.N., et al.

Pertanika Journal of Science & Technology, 2017;25(105):63-72.
MyJurnal

Rapid urbanisation and industrialisation have had an adverse and deep impact on the environment contributing to global warming and climate change. These thermal environmental problems can be even more challenging to people living in regions with warm and humid climatic conditions throughout the year, such as Malaysia. This paper analyses wind characteristics and outdoor thermal comfort index at the hottest temperatures based on data recorded hourly between 2012 and 2014 for two cities in East Malaysia, namely Kuching (Sarawak) and Kota Kinabalu (Sabah). Wind characteristics were analysed using only wind velocity and direction, while the level of outdoor thermal comfort was measured using Universal Thermal Climate Index (UTCI). The results showed that hourly average wind velocities for Kuching and Kota Kinabalu were 1.84 m/s and 2.15 m/s respectively while the highest average wind velocities was 10.1 m/s and 12.4 m/s respectively. No wind movement (i.e. 0 m/s) was recorded for both locations. The prevailing annual wind flow is generally from South-Southeast (150°) in Sarawak and from East-Southeast (110°) in Sabah. It was also found that both Kuching and Kota Kinabalu experienced strong and extreme heat stress conditions with UTCI levels of 44.8°C and 49.8°C respectively. Thus, it can be concluded that, East Malaysia faces strong and extreme heat stress conditions. This study is an original contribution on the subject of outdoor thermal environment in Malaysia, Further research to better understand outdoor thermal environmental problems is recommended.
Fulltext Cost implication analysis of concrete and Masonry waste in construction project

Kasvar, K.K., Nagapan, S., Abdullah, A.H., Ullah, K., Deraman, R., Yunus, R., et al.

Pertanika Journal of Science & Technology, 2017;25(105):177-184.
MyJurnal

Concrete and masonry waste are the main types of waste typically generated at a construction project. There is a lack of studies in the country regarding the cost implication of managing these types of construction waste To address this need in Malaysia, the study is carried out to measure the disposal cost of concrete and masonry waste. The study was carried out by a site visit method using an indirect measurement approach to quantify the quantity of waste generated at the project. Based on the recorded number of trips for waste collection, the total expenditure to dispose the waste were derived in three construction stages. Data was collected four times a week for the period July 2014 to July 2015. The total waste generated at the study site was 762.51 m3 and the cost incurred for the 187 truck trips required to dispose the waste generated from the project site to the nearby landfill was RM22,440.00. The findings will be useful to both researchers and policy makers concerned with construction waste.
Fulltext Characterisation of lateral and vertical subsurface heterogeneity in the ground using sustainable seismic surface wave methodology

Madun, A., Wijeyesekera, D.C., Ahmad Tajuddin, S.A., Zainalabidin, M.H., Yunus, R., Baharudin, M.F.

Pertanika Journal of Science & Technology, 2017;25(105):169-176.
MyJurnal

Seismic surface waves are a non-destructive technique used to obtain the dynamic properties of soil by measuring the shear wave velocity and calculating the shear modulus of soil. The shear modulus is one of the parameters to measure the stiffness of materials. This study evaluates soil profiles and the position of the sensor while conducting measurements of two , soil profiles, i.e. lateral and vertical non-homogeneities, using a continuous surface wave analysis (CSW) and multi-channel analysis of surface waves (MASW). Results showed the dispersive curve demonstrated an increased shear wave velocity with increasing depth for the sensor pair measurements on the clay (between columns), and decreased shear wave velocity with increasing depth for the sensor pair measurements on the column. In both instances the surface wave velocity results influenced by the depth and size of the wavelength, indicating that depth and wavelength controlled the volume of measurement in an elliptical shape. Therefore, the shear wave velocities and thus stiffness measured from the surface wave velocity techniques are represented the volume of soil measured across the sensor length.
Fulltext Application of supercritical antisolvent method in drug encapsulation: a review

Kalani M, Yunus R

Int J Nanomedicine, 2011;6:1429-42.
PMID: 21796245 DOI: 10.2147/IJN.S19021

The review focuses on the application of supercritical fluids as antisolvents in the pharmaceutical field and demonstrates the supercritical antisolvent method in the use of drug encapsulation. The main factors for choosing the solvent and biodegradable polymer to produce fine particles to ensure effective drug delivery are emphasized and the effect of polymer structure on drug encapsulation is illustrated. The review also demonstrates the drug release mechanism and polymeric controlled release system, and discusses the effects of the various conditions in the process, such as pressure, temperature, concentration, chemical compositions (organic solvents, drug, and biodegradable polymer), nozzle geometry, CO(2) flow rate, and the liquid phase flow rate on particle size and its distribution.
Fulltext Optimizing supercritical antisolvent process parameters to minimize the particle size of paracetamol nanoencapsulated in L-polylactide

Kalani M, Yunus R, Abdullah N

Int J Nanomedicine, 2011;6:1101-5.
PMID: 21698077 DOI: 10.2147/IJN.S18979

The aim of this study was to optimize the different process parameters including pressure, temperature, and polymer concentration, to produce fine small spherical particles with a narrow particle size distribution using a supercritical antisolvent method for drug encapsulation. The interaction between different process parameters was also investigated.
Effect of storage of shelled Moringa oleifera seeds from reaping time on turbidity removal

Golestanbagh M, Ahamad IS, Idris A, Yunus R

J Water Health, 2011 Sep;9(3):597-602.
PMID: 21976206 DOI: 10.2166/wh.2011.035

Moringa oleifera is an indigenous plant to Malaysia whose seeds are used for water purification. Many studies on Moringa oleifera have shown that it is highly effective as a natural coagulant for turbidity removal. In this study, two different methods for extraction of Moringa's active ingredient were investigated. Results of sodium chloride (NaCl) and distilled water extraction of Moringa oleifera seeds showed that salt solution extraction was more efficient than distilled water in extracting Moringa's active coagulant ingredient. The optimum dosage of shelled Moringa oleifera seeds extracted by the NaCl solution was comparable with that of the conventional chemical coagulant alum. Moreover, the turbidity removal efficiency was investigated for shelled Moringa oleifera seeds before drying in the oven under different storage conditions (i.e. open and closed containers at room temperature, 27 °C) and durations (fresh, and storage for 2, 4, 6 and 8 weeks from the time the seeds were picked from the trees). Our results indicate that there are no significant differences in coagulation efficiencies and, accordingly, turbidity removals between the examined storage conditions and periods.
Recurrent bilateral orbital myositis: case report and review of the literature

Abd-Rashid R, Hussein A, Yunus R, Naik VR, Shatriah I

Ann Trop Paediatr, 2011;31(2):173-80.
PMID: 21575325 DOI: 10.1179/1465328111Y.0000000004

Orbital myositis in children is uncommon. Recurrence is a major challenge in management. An 11-year-old Malay girl who presented with bilateral orbital myositis with recurrent attacks of diplopia is reported.
A unilateral optic perineuritis in a teenager - A case report

Ameilia A, Shatriah I, Wan-Hitam WH, Yunus R

Brain Dev, 2015 Jun;37(6):635-7.
PMID: 25457086 DOI: 10.1016/j.braindev.2014.09.011

Optic perineuritis is an uncommon inflammatory disorder that involves optic nerve sheath. Numerous case reports have been published on optic perineuritis in adults, the majority of whom had bilateral presentation. There are limited data on optic perineuritis occurring in pediatric patients. We report a teenager who presented with a unilateral sign that mimicked the presentation of optic neuritis. The orbit and brain magnetic resonance imaging confirmed features of unilateral optic perineuritis. She was treated with a high dose of corticosteroids for 2weeks, and her final visual outcome was satisfactory. No signs of relapse were noted during follow-up visits.
Fulltext Dynamic modeling of reversible methanolysis of Jatropha curcas oil to biodiesel

Syam AM, Hamid HA, Yunus R, Rashid U

ScientificWorldJournal, 2013;2013:268385.
PMID: 24363616 DOI: 10.1155/2013/268385

Many kinetics studies on methanolysis assumed the reactions to be irreversible. The aim of the present work was to study the dynamic modeling of reversible methanolysis of Jatropha curcas oil (JCO) to biodiesel. The experimental data were collected under the optimal reaction conditions: molar ratio of methanol to JCO at 6 : 1, reaction temperature of 60°C, 60 min of reaction time, and 1% w/w of catalyst concentration. The dynamic modeling involved the derivation of differential equations for rates of three stepwise reactions. The simulation study was then performed on the resulting equations using MATLAB. The newly developed reversible models were fitted with various rate constants and compared with the experimental data for fitting purposes. In addition, analysis of variance was done statistically to evaluate the adequacy and quality of model parameters. The kinetics study revealed that the reverse reactions were significantly slower than forward reactions. The activation energies ranged from 6.5 to 44.4 KJ mol⁻¹.
A preliminary study on Jatropha curcas as coagulant in wastewater treatment

Abidin ZZ, Ismail N, Yunus R, Ahamad IS, Idris A

Environ Technol, 2011 Jul;32(9-10):971-7.
PMID: 21882550

Many coagulants, mainly inorganic, are widely used in conventional water and wastewater treatment. Recent studies reported the occurrence of some chronic diseases associated with residual coagulant in treated wastewater. The use of alternative coagulants which are biodegradable and environmentally friendly could alleviate the problem associated with these diseases. This work investigates the capability of Jatropha curcas seed and presscake (the residue left after oil extraction) to reduce the turbidity of wastewater through coagulation. The coagulant was prepared by dissolving Jatropha curcas seed and presscake powder into solution. Then jar tests were conducted on kaolin solution as the model wastewater. The Jatropha seed was found to be an effective coagulant with more than 96% of turbidity removal at pH 1-3 and pH 11-12. The highest turbidity removal was recorded at pH 3 using a dosage of 120 mg/L. The flocs formed using Jatropha were observed to be bigger and to sediment faster when compared with flocs formed using alum. The turbidity removal was high (>98%) at all turbidities (100 NTU to 8000 NTU), suggesting its suitability for a wide range of industrial wastewater. The performance of Jatropha presscake after extraction of oil was also comparable to the fresh seed and alum at highly acidic and highly alkaline conditions. The addition of Jatropha did not significantly affect the pH of the kaolin samples after treatment and the sludge volume produced was less in comparison to alum. These results strongly support the use of Jatropha curcas seed and presscake as a potential coagulant agent.
Effect of physical pretreatment on dilute acid hydrolysis of water hyacinth (Eichhornia crassipes)

Harun MY, Dayang Radiah AB, Zainal Abidin Z, Yunus R

Bioresour Technol, 2011 Apr;102(8):5193-9.
PMID: 21333529 DOI: 10.1016/j.biortech.2011.02.001

Effects of different physical pretreatments on water hyacinth for dilute acid hydrolysis process (121 ± 3 °C, 5% H(2)SO(4), 60 min) were comparatively investigated. Untreated sample had produced 24.69 mg sugar/g dry matter. Steaming (121 ± 3 °C) and boiling (100 ± 3 °C) for 30 min had provided 35.9% and 52.4% higher sugar yield than untreated sample, respectively. The highest sugar yield (132.96 mg sugar/g dry matter) in ultrasonication was obtained at 20 min irradiation using 100% power. The highest sugar production (155.13 mg sugar/g dry matter) was obtained from pulverized samples. Hydrolysis time was reduced when using samples pretreated by drying, mechanical comminution and ultrasonication. In most methods, prolonging the pretreatment period was ineffective and led to sugar degradations. Morphology inspection and thermal analysis had provided evidences of structure disruption that led to higher sugar recovery in hydrolysis process.
Effect of ultrasonic pre-treatment on low temperature acid hydrolysis of oil palm empty fruit bunch

Yunus R, Salleh SF, Abdullah N, Biak DR

Bioresour Technol, 2010 Dec;101(24):9792-6.
PMID: 20719502 DOI: 10.1016/j.biortech.2010.07.074

Various pre-treatment techniques change the physical and chemical structure of the lignocellulosic biomass and improve hydrolysis rates. The effect of ultrasonic pre-treatment on oil palm empty fruit bunch (OPEFB) fibre prior to acid hydrolysis has been evaluated. The main objective of this study was to determine if ultrasonic pre-treatment could function as a pre-treatment method for the acid hydrolysis of OPEFB fibre at a low temperature and pressure. Hydrolysis at a low temperature was studied using 2% sulphuric acid; 1:25 solid liquid ratio and 100 degrees C operating temperature. A maximum xylose yield of 58% was achieved when the OPEFB fibre was ultrasonicated at 90% amplitude for 45min. In the absence of ultrasonic pre-treatment only 22% of xylose was obtained. However, no substantial increase of xylose formation was observed for acid hydrolysis at higher temperatures of 120 and 140 degrees C on ultrasonicated OPEFB fibre. The samples were then analysed using a scanning electron microscope (SEM) to describe the morphological changes of the OPEFB fibre. The SEM observations show interesting morphological changes within the OPEFB fibre for different acid hydrolysis conditions.
Spinal tuberculosis: the association between pedicle involvement and anterior column damage and kyphotic deformity

Yusof MI, Hassan E, Rahmat N, Yunus R

Spine (Phila Pa 1976), 2009 Apr 1;34(7):713-7.
PMID: 19333105 DOI: 10.1097/BRS.0b013e31819b2159

Pedicle involvement in spinal tuberculosis (TB), the prevertebral abscess formation, severity of vertebral body, and disc collapse were evaluated from magnetic resonance imaging (MRI) of the patients.
Noncompaction cardiomyopathy manifesting as retinal artery occlusion

Jin-Poi T, Shatriah I, Ng SL, Zurkurnai Y, Yunus R

JAMA Ophthalmol, 2013 Feb;131(2):263-5.
PMID: 23411903 DOI: 10.1001/jamaophthalmol.2013.587
Fulltext Towards Higher Oil Yield and Quality of Essential Oil Extracted from Aquilaria malaccensis Wood via the Subcritical Technique

Samadi M, Zainal Abidin Z, Yoshida H, Yunus R, Awang Biak DR

Molecules, 2020 Aug 26;25(17).
PMID: 32858782 DOI: 10.3390/molecules25173872

A method that delivers a high yield and excellent quality of essential oil, which retains most of its value-added compounds, and undergoes least change after the extraction process, is greatly sought after. Although chemical free methods are acceptable, they call for an extensive processing time, while the yield and quality from these methods are often disappointing. This work utilizes subcritical water technology to address these issues. In this undertaking, essential oil was extracted from Aquilaria malaccensis wood by way of subcritical conditions, and characterized through gas chromatography/mass spectroscopy (GC/MS). Optimization through response surface methodology revealed temperature to be the most critical factor for the extraction process, while the optimum conditions for temperature, sample-to-solvent ratio, and time for subcritical water extraction was revealed as 225 °C, 0.2 gr/mL, and 17 min, respectively. The subcritical water extraction technique involves two simultaneous processes, which are based on good fitting to the two-site kinetic and second order model. In comparison to the hydrodistillation method, GC/MS results indicated that the quality of A. malaccensis' wood oils, derived through the subcritical water technique, are of significantly better quality, while containing many constructive value-added compounds, such as furfural and guaiacol, which are useful for the production of pesticides and medicines. Pore size, functional groups, and morphology analysis revealed the occurrence of substantial damage to the samples, which facilitated an improved extraction of bio-products. In comparison to conventional methods, the use of the subcritical method not only involves a shorter processing time, but also delivers a higher oil yield and quality.
Hedgehog signalling molecule, SMO is a poor prognostic marker in bladder cancer

Mohd Ariffin K, Abd Ghani F, Hussin H, Md Said S, Yunus R, Veerakumarasivam A, et al.

Malays J Pathol, 2021 Apr;43(1):49-54.
PMID: 33903305

INTRODUCTION: Hedgehog (HH) pathway is an important signalling cascade for growth and patterning during embryonic development. Constitutive activation of Hedgehog pathway can be found in various types of malignancies including medulloblastoma, basal cell carcinoma, gastrointestinal, breast, pancreatic, prostate cancer and leukaemia. Little is known about the expression and role of Hedgehog signalling in bladder cancer.
MATERIALS AND METHODS: The purpose of this study was to investigate the immunohistochemical expression of SMO in 112 bladder cancer cases and determine their association with demographic and clinicopathological parameters. Bladder cancer tissues were obtained from the Hospital Kuala Lumpur.
RESULTS: SMO was expressed in the cytoplasm of all cases of bladder cancer. 6 cases (5.4%) showed low expression, while 106 cases (94.6%) showed high expression. Positive expression of SMO protein was correlated with a few variables which include grade and stage of tumour, lymph node metastasis and distant metastasis. SMO expression showed statistically significant association with higher grade (p=0.001) and higher stage (p=0.042) of bladder cancer. SMO expression also showed borderline association with lymph node metastasis (p=0.056).
CONCLUSION: These findings indicate that SMO expression may be a poor prognostic marker in bladder cancer.
Fulltext Release Mechanisms and Kinetic Models of Gypsum-Sulfur-Zeolite-Coated Urea Sealed with Microcrystalline Wax for Regulated Dissolution

Eghbali Babadi F, Yunus R, Masoudi Soltani S, Shotipruk A

ACS Omega, 2021 May 04;6(17):11144-11154.
PMID: 34056270 DOI: 10.1021/acsomega.0c04353

In this study, a mineral-based coated urea was fabricated in a rotary pan coater using a mixture of gypsum/sulfur/zeolite (G25S25Z50) as an effective and low-cost coating material. The effects of different coating compositions on the dissolution rate of urea and the crushing strength and morphology of the coated urea were investigated. A 25:25:50 (wt %) mixture of gypsum/sulfur/zeolite (G25S25Z50) increased the coating effectiveness to 34.1% with the highest crushing strength (31.06 N). The effectiveness of coated urea was further improved to 46.6% with the addition of a microcrystalline wax (3%) as a sealant. Furthermore, the release mechanisms of various urea fertilizers were determined by fitting the release profiles with six mathematical models, namely, the zeroth-order, first-order, second-order, Higuchi, Ritger & Peppas, and Kopcha models. The results showed that the release mechanism of the uncoated urea and all other coated urea followed the Ritger & Peppas model, suggesting the diffusional release from nonswellable delivery systems. In addition, due to the increased mass-transfer resistance, the kinetic constant was decreased from 0.2233 for uncoated urea to 0.1338 for G25S25Z50-coated urea and was further decreased to 0.0985 when 3% Witcovar 146 sealant was applied.
Gleason scores in prostate needle biopsy and prostatectomy specimens in prostatic adenocarcinoma: A correlation study

Awang A, Md Isa N, Yunus R, Azhar Shah S, Md Pauzi SH

Malays J Pathol, 2019 Dec;41(3):253-257.
PMID: 31901909

INTRODUCTION: Gleason scoring (GS) categorised prostatic adenocarcinoma into five prognostic grade groups (PGGs); associated with different prognosis and treatment. This study aims to correlate between Gleason scores of needle biopsies with the corresponding total prostatectomy specimens, and to assess the relationship between the percentage of Gleason 4 tumour pattern (GP4) within Gleason score 7 (GS7) needle biopsy groups with the pathological staging.
MATERIALS AND METHODS: Seventy-eight specimens of needle prostate biopsy and its subsequent radical prostatectomy were retrospectively studied. The GSs of the needle biopsy were compared with the corresponding prostatectomy specimens. The percentage of GP4 in GS7 needle biopsy groups was calculated and correlated with the pathological staging.
RESULTS: More than half (60%) of GS 6 needle biopsy cases (PGG 1) were upgraded in the prostatectomy specimen, while the majority (80%) of the GS7 needle biopsy groups (PGG 2 and 3) remain unchanged. Cohen's Kappa shows fair agreement in the Gleason scoring between needle biopsies and prostatectomy specimens, K = 0.324 (95% CI, 6.94 to 7.29), p <0.0005 and in the percentage of GP4 in GS7 needle biopsy groups and their corresponding radical prostatectomy specimens, K = 0.399 (95% CI 34.2 - 49.2), p<0.0005. A significant relationship was seen between the percentage of GP4 in GS7 needle biopsy with the pT and pN stage of its radical prostatectomy (p = 0.008 and p=0.001 respectively).
CONCLUSION: A higher percentage of GP4 in GS7 tumour is associated with worse tumour behaviour, therefore it is crucial for clinicians to realise this in deciding the optimal treatment.

Filters

Please provide feedback to Administrator ([email protected])

External Links