Displaying publications 281 - 300 of 1919 in total

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  1. Optimization of n-hexane reforming using Taguchi orthogonal array design
    Sinnathambi CM, Reem Ahmed Mohammed Ismail
    Sains Malaysiana, 2012;41:885-892.
    Taguchi orthogonal array design, a statistical software is applied to n-hexane reforming. The purpose is to identify the most significant process variable in reforming conditions favouring n-hexane conversion to high aromatics and isomers and low cracked and coke precursor reformate products. Actual experimental data were used for this study. Three process variables i.e. temperature, contact time and hydrogen partial pressure were investigated. From the study it was found that the contact time was the most critical operating parameter for n-hexane conversion followed by reaction temperature and hydrogen partial pressure. It was also noted that enhanced n-hexane reforming conversion can be achieved by operating the process at reaction temperature 723 K and contact time 7.1 min with a H2 partial pressure 300 kPa. For selectivity to aromatics and isomers lower contact time of 1.07 min with intermediate hydrogen partial pressure of 300 to 500 kPa operating at a reaction temperature of 723 K is most favourable.
    Matched MeSH terms: Partial Pressure
  2. Fulltext SmartFire: Intelligent Platform for Monitoring Fire Extinguishers and Their Building Environment
    Garcia-Martin R, González-Briones A, Corchado JM
    Sensors (Basel), 2019 May 25;19(10).
    PMID: 31130598 DOI: 10.3390/s19102390
    Due to fire protection regulations, a minimum number of fire extinguishers must be available depending on the surface area of each building, industrial establishment or workplace. There is also a set of rules that establish where the fire extinguisher should be placed: always close to the points that are most likely to be affected by a fire and where they are visible and accessible for use. Fire extinguishers are pressure devices, which means that they require maintenance operations that ensure they will function properly in the case of a fire. The purpose of manual and periodic fire extinguisher checks is to verify that their labeling, installation and condition comply with the standards. Security seals, inscriptions, hose and other seals are thoroughly checked. The state of charge (weight and pressure) of the extinguisher, the bottle of propellant gas (if available), and the state of all mechanical parts (nozzle, valves, hose, etc.) are also checked. To ensure greater safety and reduce the economic costs associated with maintaining fire extinguishers, it is necessary to develop a system that allows monitoring of their status. One of the advantages of monitoring fire extinguishers is that it will be possible to understand what external factors affect them (for example, temperature or humidity) and how they do so. For this reason, this article presents a system of soft agents that monitors the state of the extinguishers, collects a history of the state of the extinguisher and environmental factors and sends notifications if any parameter is not within the range of normal values.The results rendered by the SmartFire prototype indicate that its accuracy in calculating pressure changes is equivalent to that of a specific data acquisition system (DAS). The comparative study of the two curves (SmartFire and DAS) shows that the average error between the two curves is negligible: 8% in low pressure measurements (up to 3 bar) and 0.3% in high pressure (above 3 bar).
    Matched MeSH terms: Pressure
  3. Response: Optical Coherence Tomography Angiography of Optic Disc and Macula Vessel Density in Glaucoma and Healthy Eyes
    Yip VCH, Wong HT, Yong VKY, Lim BA, Hee OK, Cheng J, et al.
    J Glaucoma, 2019 07;28(7):e132-e133.
    PMID: 31135585 DOI: 10.1097/IJG.0000000000001289
    Matched MeSH terms: Intraocular Pressure
  4. Effect of BaAl2O4 addition on power consumption and oxygen sensing response of Er123 ceramic rods utilizing hot-spot phenomenon
    Hassan M, Yahya A, Okamoto T
    Sains Malaysiana, 2011;40.
    In this paper, we report the effect of BaAl2O4 addition (0-30 wt. %) on power consumption and oxygen sensing response of hot-spots developed on short Er123 ceramic rods of around 12 mm length synthesized using standard solid-state reaction. All the sensor rods showed increase in output current with increasing voltage followed by sudden reduction in output current and appearance of hot spot. After appearance of hot spot, for each rod, output current was observed to decrease gradually with increasing voltage with the slope of the I-V curve gradually approaching zero. Output current after the hot spot formation showed sensitivity to oxygen partial pressure, pO2 between 1 to 100 kPa. Addition of 30 wt. % BaAl2O4 reduced the fluctuation of current and increased the sensitivity for pO2 below 10 kPa. In addition, overshoot current was also reduced and resulted in improvement of response time from around 10 s to 5 s. Our result also showed that minimum power consumption was significantly reduced in the Er123 rods with 30 wt. % BaAl2O4.
    Matched MeSH terms: Partial Pressure
  5. Efficacy and quality of life in 30 hypertensive patients treated with low dose captopril
    Choy YW, Cheong I
    Family Physician, 1989;1:19-22.
    This study was carried out on 30 patients to: i) determine the efficacy of low dose captopril as monotherapy (with or without a diuretic) in the treatment of various grades of hypertension. ii) assess the quality of life of these patients 12 weeks after commencement of therapy. Our results showed that there was a sustained and significant fall in both mean systolic and diastolic blood pressure from 171.9 ± 24 to 150.5 ± 25 mm Hg and 109.0 ± 14 to 93.6 ± 15mmHg respectively (p<0.001). Improvement in quality of life was however not statistically significant (p<0.05). We concluded that low dose captopril used alone or in combination with a diuretic can be considered for the initial therapy of mild to moderate hypertension. The optimal dosage and the longterm benefits on quality of life need further evaluation in a larger series.
    Matched MeSH terms: Blood Pressure
  6. A six-year review of tubal sterilization at a district hospital (1981-1986)
    Sivalingam N, Bhagat S, Pereira R
    Family Physician, 1989;1:23-27.
    Matched MeSH terms: Blood Pressure
  7. Effect of nano- and micro- reinforced agents on dry sliding wear of polyester composites
    Chong MM, Chang SY, Noraiham Muhammad, Zulkifli Mord Rosli, Qumrul Ahsan
    Sains Malaysiana, 2014;43:959-966.
    Dry sliding wear of polyester hybrid composites containing carboxylic functionalized multi-walled carbon nanotubes (cNT) and microparticles, silica (Si02) was studied at different sliding distances. An attempt has been made to produce uniform dispersion of nano- and micro- particles in the test samples by ultrasonication. The tribological properties of the hybrid composites were performed by using pin-on-disc (POD) tester against grey cast iron countersurface. The dry sliding wear tests were carried out under pressure-velocity (pv) condition of 0.4 MPa and 4 m/s for total sliding distance of 28800 m and at an interval of every sliding distance of 3600 m, wear properties and behavior were studied. The samples containing 10 wt.% silica (microparticles) with and without CNT always show increase in coefficient of friction at the expense of wear rate. However, samples containing only ci'rr have the lowest wear rate with the increase in coefficient of friction. Sliding distance studies also provide the information on wear rates which were ever changing at different sliding distances whereas average coefficient of friction did not vary throughout the tests. SEM observations of wear surfaces showed different wear morphologies when reinforcement (cNT or Si02) incorporated into the composites either alone or in combination.
    Matched MeSH terms: Pressure
  8. A mini scale batch reactor for the production of palm‑based polyol
    Khairiah Haji Badri, Muhammad Syukri Ngah
    Sains Malaysiana, 2015;44:861-867.
    An investigation on a batch production of palm kernel oil polyol (PKO-p) was conducted via esterification and condensation.
    The process design was thoroughly studied as a preliminary step for future upscaling. The process variables included
    necessity of vacuum pump, controlling of heating rate, recording the production time, nitrogen gas flow and agitator
    speed. About 250 mL PKO-p was successfully synthesized within 3 h. Vacuum pressure was applied to haul out moisture
    from the system. The control of heating rate and production time are vital to avoid sudden oxidation.
    Matched MeSH terms: Pressure
  9. New progress in the study of intergranular suction and shear strength of unsaturated soil
    Liansheng Tang, Haitao Sang, Liqun Jiang, Yinlei Sun
    Sains Malaysiana, 2016;45:141-156.
    The suction between soil particles is the basis and core problem in the study of unsaturated soil. However, is the suction between soil particles just the matrix suction (which has been widely used since the discipline of unsaturated soil mechanics was established). In fact, the concept of matrix suction is from soil science and reflects the water-absorbing capacity of the soil. Matrix suction characterizes the interaction between soil particles and pore water rather than the interactions between soil particles, which were not in conformity with the principle of effective stress of soils. The suction of unsaturated soil, in essence, is the intergranular suction composed of absorbed suction and structural suction. In this paper, first, the basic concepts of absorbed suction and structural suction were briefly introduced. Then, with soil mechanics, powder science, crystal chemistry, granular material mechanics and other related disciplines of knowledge for reference, the quantitative calculation formulas were theoretically deduced for the absorbed suction for equal-sized and unequal-sized unsaturated soil particles with arbitrary packing and the variable structural suction for equal-sized unsaturated soil particles with arbitrary packing and unequal-sized unsaturated soil particles with close tetrahedral packing. The factors that influence these equations were discussed. Then, the shear strength theory of unsaturated soil was established based on the theory of intergranular suction through the analysis of the effective stress principle of unsaturated soil. This study demonstrates that the shear strength of unsaturated soil consists of three parts: The effective cohesive force, the additional strength caused by external loads and the strength caused by intergranular suction. The contribution of the three parts to the shear strength of unsaturated soil depends on the following influence factors: Soil type, confining pressure, water content and density. Therefore, these factors must be comprehensively considered when determining the strength of an unsaturated soil.
    Matched MeSH terms: Pressure
  10. Partial slip effect on heat and mass transfer of MHD peristaltic transport in a porous medium
    Mehmood OU, Norzie Mustapha, Sharidan Shafie, Hayat T
    Sains Malaysiana, 2014;43:1109-1118.
    This research looks at the effects of partial slip on heat and mass transfer of peristaltic transport. The magnetohydrodynamic (MHD) flow of viscous fluid in a porous asymmetric channel has been considered. The exact solutions for the stream function, longitudinal pressure gradient, longitudinal velocity, shear stress, temperature and concentration fields are derived by adopting long wavelength and small Reynolds number approximations. The results showed that peristaltic pumping and trapping are reduced with increasing velocity slip parameter. Furthermore, temperature increases with increasing thermal slip parameter. Moreover, the concentration profile decreases with increasing porosity parameter, Schmidt number and concentration slip parameter. Comparisons with published results are found to be in good agreement.
    Matched MeSH terms: Pressure
  11. An overview of the present stability and performance of eor-foam
    Mohammed Falalu Hamza, Chandra MS, Zulkifli Merican Aljunid Merican, Hassan Soleimani, D. SK
    Sains Malaysiana, 2017;46:1641-1450.
    Foam flooding technique, commonly known as foam assisted water alternating gas method (FAWAG) has been identified as an effective chemical enhanced oil recovery (CEOR) technique. The ability of EOR-foam to sweep oil in low permeable zones makes it important displacement fluid in the oil industry. However, extreme reservoir conditions such as temperature, pressure and salinity have detrimental effects on the stability and the overall performance of the EOR-foam. Consequently, understanding foam stability and performance under different conditions is crucial for long term oil field application. This paper discusses the current status of the EOR-foam stability, performance and challenges from laboratory studies to field application perspective. The paper also highlights the knowledge gaps which require further research for successful field application.
    Matched MeSH terms: Pressure
  12. Fulltext Data for molecular recognition between polyamide thin film composite on the polymeric subtract by molecular dynamic
    Wan Jusoh WZA, Abdul Rahman S, Ahmad AL, Mohd Mokhtar N
    Data Brief, 2019 Jun;24:103910.
    PMID: 31193576 DOI: 10.1016/j.dib.2019.103910
    This paper focus to examine the best molecular interaction between Polyamide Thin Film Composite (PA TFC) layers with different properties of the support membrane. The support membrane of Nylon 66 (N66) and Polyvinylidene fluoride (PVDF) was chosen to represent the hydrophilic and hydrophobic model respectively in the Molecular Dynamic (MD) simulation. The Condensed-Phase Optimized Molecular Potential for Atomistic Simulation Studies (COMPASS) force field was used with the total simulation runs were set 1000 picoseconds run production ensembles. The temperature and pressure set for both ensembles were 298 K and 1 atm respectively. The validity of our model densities data was check and calculated where the deviation must be less than 6%. The comparison between hydrophobic and hydrophilic of the support membrane data was examined by the distance and magnitude of intensity of the Radial Distribution Function (RDF's) trends.
    Matched MeSH terms: Pressure
  13. Bulk CO2 /CH4 separation for offshore operating conditions using membrane process
    Norwahyu Jusoh, Lau KK, Yeong YF, Azmi M. Shariff
    Sains Malaysiana, 2016;45:1707-1714.
    The increasing demands of natural gas pushes energy industries to explore the reservoirs contain high CO2 concentration
    and impurities including heavy hydrocarbons. High efficiency of using membrane technology in CO2
    -natural gas separation
    has extended its potential application to offshore environment. Due to the limited studies related with the separation of
    CO2
    under offshore conditions, the present work has investigated the separation performance of a commercial membrane
    in removing bulk CO2
    from methane at elevated pressure condition. A wide range of offshore operating conditions
    including pressure from 10 to 50 bar, CO2
    concentration from 25 to 70% and temperature of 30o
    C, 40o
    C and 50o
    C were
    studied. High relative CO2 permeance and relative CO2
    /CH4
    selectivity were observed when the pressure and the CO2
    concentration increased. This work, therefore substantial is to bridge the gap and facilitates the application of membrane
    technology for offshore operating conditions.
    Matched MeSH terms: Pressure
  14. Effects of different cooking methods on isoflavone content in Malaysian soy-based dishes
    Hasnah Haron, Tasneem Shaari, Chan BK
    Sains Malaysiana, 2016;45:1329-1335.
    Soy-based products are one of famous raw ingredients used in the preparation of Asian cuisines. These soy-based products are good source of isoflavones. This study was carried out to observe the effects of different cooking methods on isoflavone content in soy-based products. A total of eight Malaysian dishes prepared using soy-based products with different cooking methods was selected as samples for this study. Daidzein and genestein contents in raw and cooked soy-based products were both quantified using high performance liquid chromatography (HPLC). The results showed that dishes containing tempe as ingredients had significantly higher (p<0.05) amount of isoflavone content, in both raw and cooked forms, as compared to those prepared from other types of soy-based products when based on dry and wet. In conclusion, the isoflavone content was significantly reduced (p<0.05) in some cooked soy-based products (tempe (TSS and ML), fu jook (ML) and firm tofu (FTC)) based on dry weight as compared with the raw ones. However, the correlations between isoflavone content with cooking methods, durations and temperatures were not significant (p>0.05) in this study.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  15. Fulltext Kenaf Composites for Automotive Components: Enhancement in Machinability and Moldability
    Mohd Radzuan NA, Ismail NF, Fadzly Md Radzi MK, Razak ZB, Tharizi IB, Sulong AB, et al.
    Polymers (Basel), 2019 Oct 17;11(10).
    PMID: 31627431 DOI: 10.3390/polym11101707
    To date, the mechanical performance of kenaf composites is still unsatisfied in term of its mechanical performance. Therefore, research focuses on kenaf composites fabrication through the selection of polymer resin, including epoxy, polypropylene, and polylactic acid. The incorporated kenaf fibre at 10 wt % to 40 wt % loadings was conducted using injection and a compression moulding process. The compressed materials indicated high tensile strength at 240 MPa compared to inject materials (60 MPa). Significant improvement on impact strength (9 kJ/m2) was due to the unpulled-out fibre that dispersed homogenously and hence minimize the microcrack acquire. Meanwhile, high flexural strength (180 MPa) obtained by kenaf/epoxy composites due to the fibre orientate perpendicular to the loading directions, which improve its mechanical properties. The findings indicate that the kenaf fibre reinforced thermoset materials exhibit better mechanical properties as a function to the battery tray applications.
    Matched MeSH terms: Pressure
  16. Fulltext Current Updates on Idiopathic Normal Pressure Hydrocephalus
    Liew BS, Takagi K, Kato Y, Duvuru S, Thanapal S, Mangaleswaran B
    Asian J Neurosurg, 2019 9 10;14(3):648-656.
    PMID: 31497081 DOI: 10.4103/ajns.AJNS_14_19
    Idiopathic normal pressure hydrocephalus (iNPH) is one of the neurodegenerative diseases which can be treated surgically with favorable outcome. The gait disturbance, cognitive, and urinary symptoms are known as the clinical triad of iNPH. In this review, we have addressed the comorbidities, differential diagnoses, clinical presentations, and pathology of iNPH. We have also summarized the imaging studies and clinical procedures used for the diagnosis of iNPH. The treatment modality, outcomes, and prognosis were also discussed.
    Matched MeSH terms: Hydrocephalus, Normal Pressure
  17. Fulltext Electrical Conductivity Performance of Predicted Modified Fibre Contact Model for Multi-Filler Polymer Composite
    Mohd Radzuan NA, Sulong AB, Hui D, Verma A
    Polymers (Basel), 2019 Aug 30;11(9).
    PMID: 31480276 DOI: 10.3390/polym11091425
    Polymer composites have been extensively fabricated given that they are well-fitted for a variety of applications, especially concerning their mechanical properties. However, inadequate outcomes, mainly regarding their electrical performance, have limited their significant potential. Hence, this study proposed the use of multiple fillers, with different geometries, in order to improve the electrical conductivity of a polymer composite. The fabricated composite was mixed, using the ball milling method, before being compressed by a hot press machine at 3 MPa for 10 min. The composite plate was then measured for both its in-plane and through-plane conductivities, which were 3.3 S/cm, and 0.79 S/cm, respectively. Furthermore, the experimental data were then verified using a predicted electrical conductivity model, known as a modified fibre contact model, which considered the manufacturing process, including the shear rate and flow rate. The study indicated that the predicted model had a significant trend and value, compared to the experimental model (0.65 S/cm for sample S1). The resultant fabricated composite materials were found to possess an excellent network formation, and good electrical conductivity for bipolar plate application, when applying compression pressure of 3 MPa for 10 min.
    Matched MeSH terms: Pressure
  18. Toxicity of xylene in occupationally exposed workers: A high-performance liquid chromatography analysis
    Rajan ST, Narasimhan M, Rao KB, Jacob TE
    J Oral Maxillofac Pathol, 2019 9 14;23(2):303.
    PMID: 31516245 DOI: 10.4103/jomfp.JOMFP_297_18
    Background: Xylene is one of the most commonly used solvents in industrial and medical technologies. Several health hazards of xylene have been documented in literature. Workers in certain forces appear to have the greatest potential for exposure to high concentrations of xylene - histopathology technicians and painters are two such groups. This study was undertaken with the aim to determine the level of xylene exposure and the various systemic health effects among these groups.

    Methodology: The study was performed by analyzing the urine samples of the participants for methylhippuric acid, the established biomarker of xylene with the aid of high-performance liquid chromatography.

    Results and Conclusion: The work hours per week of the occupationally exposed participants were statistically analyzed with that of the excretory values of the metabolites of xylene, and the P value was found to be highly significant. Various side effects of xylene including respiratory, dermatological, neurological and gastrointestinal symptoms were observed among the study groups.

    Matched MeSH terms: Chromatography, High Pressure Liquid
  19. Quantification of atovaquone from amorphous solid dispersion formulation using HPLC: An in vitro and ex vivo investigation
    Teoh XY, Goh CF, Aminu N, Chan SY
    J Pharm Biomed Anal, 2021 Jan 05;192:113631.
    PMID: 33011581 DOI: 10.1016/j.jpba.2020.113631
    Atovaquone (ATQ) is a poorly soluble drug. Therefore, formulating ATQ into its supersaturated state through solid dispersion for bioavailability enhancement can be of great value. However, due to fast crystallising properties of ATQ, the quantification of ATQ in a supersaturated solid dispersion system can be complicated. Therefore, in pursuit of accurate quantification of such sample, a simple HPLC analytical method utilising a C18 column (250 × 4.6 mm ID, 5 μm) for the quantitation of ATQ has been developed and validated. Atovaquone elution using the proposed method demonstrated a retention time around 7.6 min with good linearity (R2 > 0.999). The system suitability is also detailed with the tailing factor at 1.365 ± 0.002. The addition of solubilising agent as sample treatment step aided in ensuring the accurate quantitation of the fast crystallising ATQ. The developed HPLC quantitation method has been successfully employed in the analysis of ATQ from solid dispersion samples in in vitro dissolution as well as ex vivo permeation studies for formulation development.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  20. Fulltext A Review of CFD Modelling and Performance Metrics for Osmotic Membrane Processes
    Toh KY, Liang YY, Lau WJ, Fimbres Weihs GA
    Membranes (Basel), 2020 Oct 15;10(10).
    PMID: 33076290 DOI: 10.3390/membranes10100285
    Simulation via Computational Fluid Dynamics (CFD) offers a convenient way for visualising hydrodynamics and mass transport in spacer-filled membrane channels, facilitating further developments in spiral wound membrane (SWM) modules for desalination processes. This paper provides a review on the use of CFD modelling for the development of novel spacers used in the SWM modules for three types of osmotic membrane processes: reverse osmosis (RO), forward osmosis (FO) and pressure retarded osmosis (PRO). Currently, the modelling of mass transfer and fouling for complex spacer geometries is still limited. Compared with RO, CFD modelling for PRO is very rare owing to the relative infancy of this osmotically driven membrane process. Despite the rising popularity of multi-scale modelling of osmotic membrane processes, CFD can only be used for predicting process performance in the absence of fouling. This paper also reviews the most common metrics used for evaluating membrane module performance at the small and large scales.
    Matched MeSH terms: Osmotic Pressure
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