Displaying publications 21 - 40 of 513 in total

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  1. Saleh MI, Ahmad M, Darus H
    Talanta, 1990 Jul;37(7):757-9.
    PMID: 18965016
    A series of chelating reagents, 1-phenyl-3-methyl-4-(2-fluorobenzoyl)-5-pyrazolone, 1-phenyl-3-methyl-4-(3-fluorobenzoyl)-5-pyrazolone and 1-phenyl-3-methyl-4-(4-fluorobenzoyl)-5-pyrazolone, has been synthesized. The extraction of Ln(III), (Ln = La, Eu and Lu) into chloroform with these reagents at 30 +/- 1 degrees has been studied. The composition of the complexes extracted has been determined by the slope method, and the extraction constants K(ex), were measured. The presence of the fluorine atom in the reagents does not make the K(ex), values much different from those obtained with the parent pyrazolone.
  2. Sarfaraz M, Ahmad MK, Kılıçman A
    J Inequal Appl, 2017;2017(1):81.
    PMID: 28479833 DOI: 10.1186/s13660-017-1351-x
    The resolvent operator approach is applied to address a system of generalized ordered variational inclusions with ⊕ operator in real ordered Banach space. With the help of the resolvent operator technique, Li et al. (J. Inequal. Appl. 2013:514, 2013; Fixed Point Theory Appl. 2014:122, 2014; Fixed Point Theory Appl. 2014:146, 2014; Appl. Math. Lett. 25:1384-1388, 2012; Fixed Point Theory Appl. 2013:241, 2013; Eur. J. Oper. Res. 16(1):1-8, 2011; Fixed Point Theory Appl. 2014:79, 2014; Nonlinear Anal. Forum 13(2):205-214, 2008; Nonlinear Anal. Forum 14: 89-97, 2009) derived an iterative algorithm for approximating a solution of the considered system. Here, we prove an existence result for the solution of the system of generalized ordered variational inclusions and deal with a convergence scheme for the algorithms under some appropriate conditions. Some special cases are also discussed.
  3. REID JA, AHMAD MD
    Med J Malaya, 1958 Jun;12(4):569-84.
    PMID: 13577150
  4. Suid MH, Ahmad MA
    ISA Trans, 2021 Dec 16.
    PMID: 34991880 DOI: 10.1016/j.isatra.2021.11.037
    Automatic Voltage Regulator (AVR) is fabricated to sustain the voltage level of a synchronous generator spontaneously. Several control strategies have been introduced into the AVR system with the aim of gaining a better dynamic response. One of the most universally utilized controllers is the Proportional-Integral-Derivative (PID) controller. Despite the PID controller having a relatively high dynamic response, there are still further possibilities to improve in order to obtain more appropriate responses. This paper designed a sigmoid-based PID (SPID) controller for the AVR system in order to allow for an accelerated settling to rated voltage, as well as increasing the control accuracy. In addition, the parameters of the proposed SPID controller are obtained using an enhanced self-tuning heuristic optimization method called Nonlinear Sine Cosine Algorithm (NSCA), for achieving a better dynamic response, particularly with regards to the steady-state errors and overshoot of the system. A time-response specifications index is used to validate the proposed SPID controller. The obtained simulation results revealed that the proposed method was not only highly effective but also greatly improved the AVR system transient response in comparison to those with the modern heuristic optimization based PID controllers.
  5. Suah FBM, Ahmad M
    Anal Chim Acta, 2017 Jan 25;951:133-139.
    PMID: 27998481 DOI: 10.1016/j.aca.2016.11.040
    The use of a polymer inclusion membrane (PIM) as a sensing material is a new approach to overcome the selectivity and stability drawbacks of the optical chemical sensor (optode). In this study, non-plasticized PIM containing poly(vinyl chloride) as a support base, sodium morin-5-sulfonate (NaMSA) as a reagent and Aliquat 336 as a fixed carrier (ionophore) was prepared and its performance was tested for application in an optode to determine Al3+ ions. The results showed that PIM properties are greatly influenced by the membrane composition. The studies revealed that the optode response was dependent on film thickness, the presence of plasticizer, stirring effect, concentration of NaMSA, concentration of Aliquat 336 and pH of the aqueous solution used. The dynamic range of Al3+ ions concentration determined using this optode was linear from 5.19 × 10-7 to 6.00 × 10-5 mol L-1 and the calculated limit of detection (L.O.D.) was found to be 4.07 × 10-7 mol L-1. The maximum emission wavelength (λem) for the PIM based optode was 512 nm. Scanning electron microscopy analysis of the PIM revealed that a dense texture was formed. Fourier transform infra-red and thermal gravimetry analysis characterizations proved that all of the constituents of the PIM remain within the membrane. The PIM developed in this work was found to be stable, has good mechanical strength, and is sensitive and reusable. Lastly, the PIM was successfully applied as an optical sensor for determination of Al3+ ions in an aqueous solution.
  6. Suah FB, Ahmad M, Heng LY
    PMID: 25748985 DOI: 10.1016/j.saa.2015.02.068
    A novel approach for the determination of Al(3+) from aqueous samples was developed using an optode membrane produced by physical inclusion of Al(3+) selective reagent, which is morin into a plasticized poly(vinyl chloride). The inclusion of Triton X-100 was found to be valuable and useful for enhancing the sorption of Al(3+) ions from liquid phase into the membrane phase, thus increasing the intensity of optode's absorption. The optode showed a linear increase in the absorbance at λ(max)=425 nm over the concentration range of 1.85×10(-6)-1.1×10(-4) mol L(-1) (0.05-3 μg mL(-1)) of Al(3+) ions in aqueous solution after 5 min. The limit of detection was determined to be 1.04×10(-6) mol L(-1) (0.028 μg mL(-1)). The optode developed in the present work was easily prepared and found to be stable, has good mechanical strength, sensitive and reusable. In addition, the optode was tested for Al(3+) determination in lake water, river water and pharmaceutical samples, which the result was satisfactory.
  7. Suah FB, Ahmad M, Heng LY
    J Fluoresc, 2014 Jul;24(4):1235-43.
    PMID: 24871034 DOI: 10.1007/s10895-014-1406-z
    This paper reports the use of a polymer inclusion membranes (PIMs) for direct determination of Al(III) ions in natural water by using a fluorescence based optode. The best composition of the PIMs consisted of 60 wt.% (m/m) poly (vinyl chloride) (PVC) as the base polymer, 20 wt.% (m/m) triton X-100 as an extractant, 20 wt.% (m/m) dioctyl phthalate (DOP) as plasticizer and morin as the reagent, was used in this study. The inclusion of triton X-100 was used for enhancing the sorption of Al(III) ions from liquid phase into the membrane phase, thus increasing the optode fluorescence intensity. The optimized optode was characterized by a linear calibration curve in the range from 7.41 × 10(-7) to 1.00 × 10(-4) molL(-1) of Al(III), with a detection limit of 5.19 × 10(-7) molL(-1). The response of the optode was 4 min and reproducible results were obtained for eight different membranes demonstrated good membrane stability. The optode was applied to the determination of Al(III) in natural water samples. The result obtained is comparable to atomic absorption spectrometry method.
  8. Saad R, Ahmad MZ, Abu MS, Jusoh MS
    ScientificWorldJournal, 2014;2014:865495.
    PMID: 24782670 DOI: 10.1155/2014/865495
    Multicriteria decision making (MCDM) is one of the methods that popularly has been used in solving personnel selection problem. Alternatives, criteria, and weights are some of the fundamental aspects in MCDM that need to be defined clearly in order to achieve a good result. Apart from these aspects, fuzzy data has to take into consideration that it may arise from unobtainable and incomplete information. In this paper, we propose a new approach for personnel selection problem. The proposed approach is based on Hamming distance method with subjective and objective weights (HDMSOW's). In case of vagueness situation, fuzzy set theory is then incorporated onto the HDMSOW's. To determine the objective weight for each attribute, the fuzzy Shannon's entropy is considered. While for the subjective weight, it is aggregated into a comparable scale. A numerical example is presented to illustrate the HDMSOW's.
  9. Ahmad MS, Razak IA, Borromeo GL
    Eur J Dent Educ, 2015 Feb;19(1):44-52.
    PMID: 24779684 DOI: 10.1111/eje.12101
    A compromised oral health condition amongst patients with special health care needs (SHCN) has been associated with the reluctance and shortage of skills of dental professionals in managing such patients. Lack of training and experience at the undergraduate level are reported barriers to the provision of care for this patient cohort. Undergraduate education therefore, plays an important role in producing professionals with the knowledge, skills and positive attitude in treating patients with SHCN. This study aims to determine the level of knowledge, comfort and attitudes of Malaysian undergraduate dental students towards caring for patients with SHCN, as well as their perception on education in this field. A self-administered questionnaire was administered in the classroom style to final year undergraduate dental students in Malaysian public dental schools. Most students were aware of Special Needs Dentistry (SND) as a specialty after being informed by academic staff. The majority of the students demonstrated poor knowledge in defining SND and felt uncomfortable providing care for such patients. They perceived their undergraduate training in SND as inadequate with most students agreeing that they should receive didactic and clinical training at undergraduate level. A high percentage of students also expressed interest in pursuing postgraduate education in this area of dentistry despite the lack of educational exposure during undergraduate years. The study supports a need for educational reform to formulate a curriculum that is more patient-centred, with earlier clinical exposure in various clinical settings for students to treat patients with special health care needs, applying the concept of holistic care in a variable clinical condition.
  10. Ahmad MZ, Hasan MK, Abbasbandy S
    ScientificWorldJournal, 2013;2013:454969.
    PMID: 24082853 DOI: 10.1155/2013/454969
    We study a fuzzy fractional differential equation (FFDE) and present its solution using Zadeh's extension principle. The proposed study extends the case of fuzzy differential equations of integer order. We also propose a numerical method to approximate the solution of FFDEs. To solve nonlinear problems, the proposed numerical method is then incorporated into an unconstrained optimisation technique. Several numerical examples are provided.
  11. Ahmad M, Yamin BM, Mat Lazim A
    Chem Cent J, 2013;7:85.
    PMID: 23680098 DOI: 10.1186/1752-153X-7-85
    α-Mangostin was extracted with methanol from the rind of mangosteen fruit and purified by using silica gel column chromatography technique. The compound is characterised using infrared, (13)C and (1)H NMR as well as UV-vis spectroscopy. The α-mangostin dispersion in colloidal systems was studied by incorporating it with an ionic microgel, poly (N-Isopropylacrylamide)-co-2VP at different pH.
  12. Ulianas A, Heng LY, Ahmad M
    Sensors (Basel), 2011;11(9):8323-38.
    PMID: 22164078 DOI: 10.3390/s110908323
    New acrylic microspheres were synthesised by photopolymerisation where the succinimide functional group was incorporated during the microsphere preparation. An optical biosensor for urea based on reflectance transduction with a large linear response range to urea was successfully developed using this material. The biosensor utilized succinimide-modified acrylic microspheres immobilized with a Nile blue chromoionophore (ETH 5294) for optical detection and urease enzyme was immobilized on the surface of the microspheres via the succinimide groups. No leaching of the enzyme or chromoionophore was observed. Hydrolysis of the urea by urease changes the pH and leads to a color change of the immobilized chromoionophore. When the color change was monitored by reflectance spectrophotometry, the linear response range of the biosensor to urea was from 0.01 to 1,000 mM (R2 = 0.97) with a limit of detection of 9.97 μM. The biosensor response showed good reproducibility (relative standard deviation = 1.43%, n = 5) with no interference by major cations such as Na+, K+, NH4+ and Mg2+. The use of reflectance as a transduction method led to a large linear response range that is better than that of many urea biosensors based on other optical transduction methods.
  13. Husaini R, Ahmad M, Soo-Beng Khoo A
    BMC Res Notes, 2011;4:551.
    PMID: 22185663 DOI: 10.1186/1756-0500-4-551
    Nasopharyngeal carcinoma (NPC) is an epithelial malignancy, which commonly occurs in Southern China, Taiwan, North Africa and Southeast Asia. Nasopharyngeal carcinoma is strongly associated with Epstein-Barr virus infection. The p53 tumour suppressor protein is rarely mutated in NPC suggesting that the inactivation of p53 pathway in NPC could be due to the presence of EBV proteins. The aim of this work was to determine the effects of EBV proteins namely LMP1 and LMP2A on the expression levels of p53 protein.
  14. Kaur H, Ahmad M, Scaria V
    Interdiscip Sci, 2016 Mar;8(1):95-101.
    PMID: 26298582 DOI: 10.1007/s12539-015-0273-x
    There is emergence of multidrug-resistant Salmonella enterica serotype typhi in pandemic proportions throughout the world, and therefore, there is a necessity to speed up the discovery of novel molecules having different modes of action and also less influenced by the resistance formation that would be used as drug for the treatment of salmonellosis particularly typhoid fever. The PhoP regulon is well studied and has now been shown to be a critical regulator of number of gene expressions which are required for intracellular survival of S. enterica and pathophysiology of disease like typhoid. The evident roles of two-component PhoP-/PhoQ-regulated products in salmonella virulence have motivated attempts to target them therapeutically. Although the discovery process of biologically active compounds for the treatment of typhoid relies on hit-finding procedure, using high-throughput screening technology alone is very expensive, as well as time consuming when performed on large scales. With the recent advancement in combinatorial chemistry and contemporary technique for compounds synthesis, there are more and more compounds available which give ample growth of diverse compound library, but the time and endeavor required to screen these unfocused massive and diverse library have been slightly reduced in the past years. Hence, there is demand to improve the high-quality hits and success rate for high-throughput screening that required focused and biased compound library toward the particular target. Therefore, we still need an advantageous and expedient method to prioritize the molecules that will be utilized for biological screens, which saves time and is also inexpensive. In this concept, in silico methods like machine learning are widely applicable technique used to build computational model for high-throughput virtual screens to prioritize molecules for advance study. Furthermore, in computational analysis, we extended our study to identify the common enriched structural entities among the biologically active compound toward finding out the privileged scaffold.
  15. Alwi N, Harun D, Omar B, Ahmad M, Zagan M, Leonard JH
    Clin Ter, 2015 Nov-Dec;166(6):e361-4.
    PMID: 26794817 DOI: 10.7417/T.2015.1901
    Caregivers face challenges to adapt while handling individual with learning disabilities (LD). The Family Crisis Oriented Personal Evaluation Scale (F-COPES) is a widely used instrument to measure coping strategies among caregivers. The current study performed cross cultural translation of F-COPES in Malay language. This study aims to examine the reliability by testing internal consistency of Malay version of F-COPES which is developed through back to back translation method from original English version.
  16. Ahmad M, Jung LT, Bhuiyan MA
    Comput Biol Med, 2016 Feb 1;69:144-51.
    PMID: 26773936 DOI: 10.1016/j.compbiomed.2015.12.017
    A coding measure scheme numerically translates the DNA sequence to a time domain signal for protein coding regions identification. A number of coding measure schemes based on numerology, geometry, fixed mapping, statistical characteristics and chemical attributes of nucleotides have been proposed in recent decades. Such coding measure schemes lack the biologically meaningful aspects of nucleotide data and hence do not significantly discriminate coding regions from non-coding regions. This paper presents a novel fuzzy semantic similarity measure (FSSM) coding scheme centering on FSSM codons׳ clustering and genetic code context of nucleotides. Certain natural characteristics of nucleotides i.e. appearance as a unique combination of triplets, preserving special structure and occurrence, and ability to own and share density distributions in codons have been exploited in FSSM. The nucleotides׳ fuzzy behaviors, semantic similarities and defuzzification based on the center of gravity of nucleotides revealed a strong correlation between nucleotides in codons. The proposed FSSM coding scheme attains a significant enhancement in coding regions identification i.e. 36-133% as compared to other existing coding measure schemes tested over more than 250 benchmarked and randomly taken DNA datasets of different organisms.
  17. Ahmad M, Roy RA, Kamarudin AG
    Int Endod J, 1994 Jan;27(1):26-31.
    PMID: 7806408
    The present study was undertaken to see if there was any variability in the power output of Piezon-Master 400 ultrasonic files when driven using different generators, tranducers and file holders. The displacement amplitude of the oscillating tip of the file in air was used as a measure of the power output. The results showed that there was considerable variability in the power output of Piezon-Master 400 ultrasonic files of similar size and length when driven using different generators, transducers and file holders. In consideration of this, it is recommended that a calibration device be incorporated in the ultrasonic unit so that the operator will have some knowledge of when the unit is working at its maximum efficiency.
  18. Ahmad M, Roy RA, Kamarudin AG, Safar M
    Int Endod J, 1993 Mar;26(2):120-4.
    PMID: 8330934
    The pattern of oscillation of a Piezon-Master 400 ultrasonic file driven by a piezoelectric transducer was studied in air and on water. In addition, the displacement amplitudes of the files were measured. The findings were compared with those observed with the Cavi-Endo unit reported in another study (Ahmad 1969). It was observed that the file vibrated such that a standing wave was formed on the file and it exhibited points of maximum deflection (antinode) and points of minimum deflection (node) with the largest deflection occurring at the apical end. This pattern of oscillation was similar to that exhibited by the Cavi-Endo file which employed a magnetostrictive transducer. However, the displacement amplitudes were very much higher than those exhibited by the Cavi-Endo. It is considered that the 120 degrees angle of the file holder inherent in the Piezon-Master 400 unit and the more effective power transmission with the piezoelectric transducer may have contributed to the large amplitudes.
  19. Ahmad M, Roy RA, Kamarudin AG
    Endod Dent Traumatol, 1992 Oct;8(5):189-94.
    PMID: 1302678
    The steady acoustic streaming generated around straight and precurved oscillating ultrasonic files driven by the Piezon-Master 400 unit was examined in the free field and in small channels using a stereomicroscope. In addition, the effect of file-wall contact on streaming production was also investigated. The results indicated that the ultrasonic files can generate acoustic streaming both in the free field and in the small channel. Higher velocity streaming was observed when smaller size files were employed and when the file was precurved. Light file-wall contact did not totally inhibit streaming while severe file-wall contact inhibited movement of the file and, as a result, no streaming was observed. The positions and length scales of the streaming vortices appeared to be influenced by the presence of boundaries. In the free field, two rows of vortices were situated along the sides of the file while in the small channel, the vortices were positioned above the surface of the file. These results indicated that it is possible for acoustic streaming to occur in a confined space as in a root canal provided that severe file-wall contact is avoided. It is therefore recommended that light filing or allowing the file to freely vibrate during some stage of treatment should be carried out in order to generate streaming in the root canal.
  20. Sharma S, Ghani AA, Win N, Ahmad M
    Med J Malaysia, 1995 Dec;50(4):372-6.
    PMID: 8668059
    This prospective study was designed to compare the effectiveness of esmolol (either 100 mg or 200 mg) with a placebo in blunting the haemodynamic response to laryngoscopy and intubation. Seventy-five patients of ASA I or II scheduled for routine-surgery were selected and entered into a placebo-controlled study. Patients were randomly allocated to receive placebo, 100 mg or 200 mg of esmolol IV as part of an anaesthetic induction technique. There were no significant differences in the demographic distribution of the patients in the study. There was no statistical difference in the baseline heart rate (HR) and systolic blood pressure (SBP) between the three groups. One minute after the administration of the drug (prior to intubation) the differences in HR between the placebo group and both the 100 mg and 200 mg groups were significant (p < 0.05), and also at 1 min and 2 min following intubation for the 200 mg group (p < 0.05). In the 200 mg group there was a significant decrease, compared with placebo, in SBP at 1 min (p < 0.05) and at 2 min (p < 0.05) after intubation. In this study, adequate haemodynamic control following was obtained with the administration of 200 mg of esmolol.
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