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National Policies and strategies on science and technology for development

Ayob A

Dev Forum, 1979.
PMID: 12261806
Fulltext Effects of Eurycoma Longifolia extract on the isolated rat heart

Mokhtar RH, Abdullah N, Ayob A

International Medical Journal Malaysia, 2014;13(1):25-34.
MyJurnal

Introduction: Eurycoma longifolia (E. longifolia) which is better known locally as Tongkat Ali is an indigenous plant in Malaysia. It belongs to the family of Simaroubaceae and is popular as a traditional medicine for its aphrodisiac properties. Throughout the years, several studies have been conducted to prove its effect on aphrodisiac action, antimalarial, antibacterial and anxiolytic properties but its effect to the cardiovascular system had not been fully explored. This study was aimed to demonstrate the changes that take place in the isolated heart following the injection of the extract. Methods: Three parameters that were measured included the coronary perfusion pressure (CPP), the left ventricular developed pressure (LVDP) and the heart rate (HR). Eighteen isolated rat hearts were used and were divided equally into three groups. The first group was to observe the effect of Isoprenaline, a β agonist while the second group was to see the effect of sodium nitroprusside (SNP), a nitric oxide (NO) donor. The dose which gave the maximum effect for these two positive controls was used to compare with the effect of E. longifolia water extract in the third group of rats. Isolated heart was mounted using the Langendorff apparatus and perfused with modified Krebs-Henseleit buffer. Doses of controls and the extract were instilled through an injection port, and the effect of each dose was monitored. Results: E. longifolia extract was found to reduce the CPP in normotensive rat at two of the highest doses. A dose of 1.0 mg of the extract reduced the CPP significantly from 34.52 ± 4.99 mmHg of the baseline value to 31.99 ± 4.93 mmHg while the dose of 10.0 mg of the extract reduced the CPP
significantly to 32.67 ± 3.89 mmHg. However, there were no significant changes of effect of the extract on the LVDP and HR as compared to control. Conclusion: These early findings suggest that E. longifolia extract may have vasodilatory property, which supports its traditional usage with minimum cardiovascular side effects.
Blood pressure variability in patients with diabetes mellitus

Mokhtar RH, Ayob A, Mohd Noor N

Asian Cardiovasc Thorac Ann, 2010 Aug;18(4):344-8.
PMID: 20719784 DOI: 10.1177/0218492310375723

Reduced arterial compliance in patients with diabetes mellitus has been shown in several studies, but it has not been significantly associated with either atherosclerosis or vessel wall thickness. Blood pressure variability is still poorly explored in diabetic patients. The aim of this study was to compare blood pressure variability and arterial compliance in patients with type 2 diabetes mellitus and controls matched for sex, age, and weight. Arterial compliance was measured and noninvasive 24-h ambulatory blood pressure monitoring was performed in 18 diabetic patients and 18 controls. There was significantly higher 24-h systolic blood pressure variability (17.7 +/- 6.8 vs. 14.6 +/- 2.6 mm Hg), diastolic blood pressure variability (15.6 +/- 7.1 vs. 11.4 +/- 3.1 mm Hg), and mean arterial blood pressure variability (14.8 +/- 7.0 vs. 11.1 +/- 2.9) in diabetic patients. Systolic, diastolic, and mean arterial blood pressure variability was significantly higher during daytime but not night time in diabetic patients compared to controls. Diabetic patients also had significantly reduced small artery compliance, but no differences in large artery compliance, cardiac output, or systemic vascular resistance. The findings suggest that hyperglycemia may affect the compliance of the vascular system, resulting in high blood pressure fluctuations.
Fulltext Outbreak of influenza amongst residential school students in Malaysia

Ayob A, Selviendran N, Hampson AW, Barr IG, Kumarasamy V, Chua KB

Med J Malaysia, 2006 Jun;61(2):168-72.
PMID: 16898307 MyJurnal

In the months of July and August 2003, an outbreak of acute respiratory illness caused by influenza A virus occurred among students in seven residential schools situated in the northern part (Perak) of Peninsular Malaysia. Out of 4989 students, aged 13 to 18 years (mean = 15.9), 1419 (28%) were effected by influenza-like illness. All patients were treated as outpatients except for 36 students who required admission for high fever, severe coughing and shortness of breath. Abnormal chest X-ray findings were noted for those that required inpatient management. Influenza A virus was isolated from 37 sputum specimens, 20 throat swabs and three nasal swab specimens from a total of 278 clinical samples obtained from 180 patients. Isolates from each of the outbreaks were sent to WHO Collaborating Centre for Reference and Research on Influenza, Melbourne, Australia for antigenic and genetic analysis. One school outbreak was due to influenza A (H1N1), A/New Caledonia/20/99-like virus while the other six school outbreaks were due to influenza A (H3N2) viruses which were A/Fujian/411/2002-like).
Effects of temperature change and beverage on mechanical and tribological properties of dental restorative composites

Ayatollahi MR, Yahya MY, Karimzadeh A, Nikkhooyifar M, Ayob A

Mater Sci Eng C Mater Biol Appl, 2015 Sep;54:69-75.
PMID: 26046269 DOI: 10.1016/j.msec.2015.05.004

The aim of this study was to investigate the effects of temperature change and immersion in two common beverages on the mechanical and tribological properties for three different types of dental restorative materials. Thermocycling procedure was performed for simulating temperature changes in oral conditions. Black tea and soft drink were considered for beverages. Universal composite, universal nanohybrid composite and universal nanofilled composite, were used as dental materials. The nanoindentation and nanoscratch experiments were utilized to determine the elastic modulus, hardness, plasticity index and wear resistance of the test specimens. The results showed that thermocycling and immersion in each beverage had different effects on the tested dental materials. The mechanical and tribological properties of nanohybrid composite and nanocomposite were less sensitive to temperature change and to immersion in beverages in comparison with those of the conventional dental composite.
Fulltext Seroprevalence survey of Chikungunya virus in Bagan Panchor, Malaysia

Ayu SM, Lai LR, Chan YF, Hatim A, Hairi NN, Ayob A, et al.

Am J Trop Med Hyg, 2010 Dec;83(6):1245-8.
PMID: 21118929 DOI: 10.4269/ajtmh.2010.10-0279

In 2006, an outbreak of Chikungunya virus (CHIKV) of the Asian genotype affected over 200 people in Bagan Panchor village in Malaysia. One year later, a post-outbreak survey was performed to determine attack rate, asymptomatic rate, and post-infection sequelae. Findings were compared with recent CHIKV outbreaks of the Central/East African genotype. A total of 180 residents were interviewed for acute symptoms and post-infection physical quality of life and depressive symptoms. Sera from 72 residents were tested for CHIKV neutralizing antibodies. The estimated attack rate was 55.6%, and 17.5% of infected residents were asymptomatic. Arthralgia was reported up to 3 months after infection, but there were no reports of long-term functional dependence or depression. Symptomatic and seropositive residents were significantly more likely to live in the area with the most dense housing and commercial activities. CHIKV had a high attack rate and considerable clinical impact during the Bagan Panchor outbreak.
Fulltext Failure of Glass Fibre-Reinforced Polypropylene Metal Laminate Subjected to Close-Range Explosion

Bassiri Nia A, Xin L, Yahya MY, Ayob A, Farokhi Nejad A, Rahimian Koloor SS, et al.

Polymers (Basel), 2020 Sep 19;12(9).
PMID: 32961655 DOI: 10.3390/polym12092139

The present study investigates the effects of close-range blast loading of fibre metal laminates (FMLs) fabricated from woven glass polypropylene and aluminium alloy 2024-T3. The polypropylene layers and anodized aluminium are stacked in 3/2 layering configuration to investigate the impact energy absorbed through deformation and damage. In order to study the blast responses of FMLs, a 4-cable instrumented pendulum blast set-up is used. Effects of blast impulse and stand-off distance were examined. Investigation of the cross-section of FMLs are presented and damages such as fibre fracture, debonding, and global deformation are examined. Increasing stand-off distance from 4 to 14 mm resulted in a change of damage mode from highly localized perforation to global deformation.
Fulltext The enlightenment from Malaysian consumers' perspective toward cosmetic products

Ayob A, Awadh AI, Jafri J, Jamshed S, Ahmad HM, Hadi H

J Pharm Bioallied Sci, 2016 Jul-Sep;8(3):229-34.
PMID: 27413352 DOI: 10.4103/0975-7406.174232

Variety of cosmetic products was used in our daily life, yet the amount and types of the cosmetic products used by the consumers were varied, which may be due to the different perspectives held by each of the consumers.
Fulltext Malaysian consumers' awareness, perception, and attitude toward cosmetic products: Questionnaire development and pilot testing

Ayob A, Awadh AI, Hadi H, Jaffri J, Jamshed S, Ahmad HM

J Pharm Bioallied Sci, 2016;8(3):203-9.
PMID: 27413348 DOI: 10.4103/0975-7406.171681

BACKGROUND: Increased usage of cosmetic products has caused a growing concern about the safety of these products, and yet little is known about cosmetics from the consumers' perspective. Hence, this study's aim is to develop a valid and reliable tool for assessing consumers' awareness, perceptions, and attitudes toward cosmetic products.
MATERIALS AND METHODS: A questionnaire was developed in the English language based on information collected from a literature search, in-depth interviews conducted with consumers prior to this study and consultations with experts. Subsequently, the questionnaire was subjected to translation, validation, and test-retest reliability. A final version of the questionnaire was piloted among 66 consumers via convenient sampling. A descriptive analysis was performed, and the internal consistency and the differences between variables in the questionnaire were analyzed.
RESULTS: The developed and translated questionnaire produced repeatable data for each of the domains (Spearman's correlation ≥ 0.7, P < 0.001). The internal consistency for awareness, perceptions and attitudes indicates good internal consistency (Cronbach's alpha value of more than 0.7 for each domain). Significant differences were found between the perception scores for the race, religion, and monthly expenses for cosmetic products, respectively, and the same pattern was found for the attitude scores, but monthly expenses for cosmetic products was replaced by monthly income.
CONCLUSION: The results achieved via the Bahasa Malaysia questionnaire indicated that the developed and translated questionnaire can be used as a valid and reliable tool for assessing consumers' awareness, perceptions, and attitudes toward cosmetic products in Malaysia in future studies.
Fulltext Effect of frying on the rheological and chemical properties of palm oil and its blends

Siddique BM, Muhamad II, Ahmad A, Ayob A, Ibrahim MH, Ak MO

J Food Sci Technol, 2015 Mar;52(3):1444-52.
PMID: 25745212 DOI: 10.1007/s13197-013-1124-6

The aim of this research was to determine the changes in the physicochemical properties of palm oil and its blends by FTIR and rheological measurements. Application of heat produces some chemical compounds as impurities and even toxic compounds in oils and fats that give absorbance at different region. FTIR spectra of pure palm olein shows an absorbance at 3002 cm(-1) whereas other pure oils show maximum absorption at around 3007 cm(-1) due to C-H stretching vibration of cis-double bond (=C-H). By blending of high unsaturated oils with palm olein, a clear shift of 3007 cm(-1) band to 3005 cm(-1) occurs. Viscosity of palm olein was found higher among all oils while it subsequently and substantially reduced by blending with other oils. Since it is a function of temperature, viscosity of pure oils and their blends decreases with the increase of temperature. The loss modulus (G''), for all oil blends before and after frying, in rheological experiment was found higher for all oils than the storage modulus (G'), therefore, the viscous property was found higher than elastic property of oils and blends. However, the critical stress for all oil blends was found higher than that of pure oils.
Fulltext Toward Enhanced State of Charge Estimation of Lithium-ion Batteries Using Optimized Machine Learning Techniques

Hannan MA, Lipu MSH, Hussain A, Ker PJ, Mahlia TMI, Mansor M, et al.

Sci Rep, 2020 Mar 13;10(1):4687.
PMID: 32170100 DOI: 10.1038/s41598-020-61464-7

State of charge (SOC) is a crucial index used in the assessment of electric vehicle (EV) battery storage systems. Thus, SOC estimation of lithium-ion batteries has been widely investigated because of their fast charging, long-life cycle, and high energy density characteristics. However, precise SOC assessment of lithium-ion batteries remains challenging because of their varying characteristics under different working environments. Machine learning techniques have been widely used to design an advanced SOC estimation method without the information of battery chemical reactions, battery models, internal properties, and additional filters. Here, the capacity of optimized machine learning techniques are presented toward enhanced SOC estimation in terms of learning capability, accuracy, generalization performance, and convergence speed. We validate the proposed method through lithium-ion battery experiments, EV drive cycles, temperature, noise, and aging effects. We show that the proposed method outperforms several state-of-the-art approaches in terms of accuracy, adaptability, and robustness under diverse operating conditions.
Fulltext WS2: A New Window Layer Material for Solar Cell Application

Bin Rafiq MKS, Amin N, Alharbi HF, Luqman M, Ayob A, Alharthi YS, et al.

Sci Rep, 2020 Jan 21;10(1):771.
PMID: 31964954 DOI: 10.1038/s41598-020-57596-5

Radio frequency (RF) magnetron sputtering was used to deposit tungsten disulfide (WS2) thin films on top of soda lime glass substrates. The deposition power of RF magnetron sputtering varied at 50, 100, 150, 200, and 250 W to investigate the impact on film characteristics and determine the optimized conditions for suitable application in thin-film solar cells. Morphological, structural, and opto-electronic properties of as-grown films were investigated and analyzed for different deposition powers. All the WS2 films exhibited granular morphology and consisted of a rhombohedral phase with a strong preferential orientation toward the (101) crystal plane. Polycrystalline ultra-thin WS2 films with bandgap of 2.2 eV, carrier concentration of 1.01 × 1019 cm-3, and resistivity of 0.135 Ω-cm were successfully achieved at RF deposition power of 200 W. The optimized WS2 thin film was successfully incorporated as a window layer for the first time in CdTe/WS2 solar cell. Initial investigations revealed that the newly incorporated WS2 window layer in CdTe solar cell demonstrated photovoltaic conversion efficiency of 1.2% with Voc of 379 mV, Jsc of 11.5 mA/cm2, and FF of 27.1%. This study paves the way for WS2 thin film as a potential window layer to be used in thin-film solar cells.