19672 research outputs found
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Cranial neural tube defect after trimethoprim exposure
No full textObjectives: The Neural Tube Defects Research Group of University of Malaya was approached to analyze a tablet named TELSE, which may have resulted in a baby born with central nervous system malformation at the University of Malaya Medical Centre. In this animal experimental study, we investigated the content of TELSE and exposure of its contents that resulted in failure of primary neurulation. Results: Liquid Chromatography Tandem Mass spectrophotometry analysis of the TELSE tablet confirmed the presence of trimethoprim as the active compound. The TELSE tablet-treated females produced significant numbers of embryos with exencephaly (n = 8, 36.4%,∗P < 0.0001), in all litters. The TELSE tablet-treated females subsequently given folic acid did not result in pregnancies despite there being evidence of possible resorption. Furthermore, after multiple rounds of mating which did not yield viable pregnancies, eventually, 2 embryos with exencephaly were harvested in a litter of 6 at 0.05% w/v pure trimethoprim once. The use of trimethoprim, a folic acid antagonist, peri-conceptionally increased the risk of exencephaly in the mouse
Ethnic Enterprises, Class Resources and Market Conditions: Indian owned SMEs in Malaysia
No full textThis article investigates changes in the conduct of ethnic enterprises following the emergence of a new generation of owners with varying class resources and as market conditions transform. The case study method is used to examine the impact of changing class resources and market conditions on ethnically-based enterprises, exploring the effects of generational transitions among small Indian owned companies in the food industry in Malaysia. The results provide an insight into key changes in the evolution of Indian owned enterprises. They indicate that changes in class resources and market conditions have enabled Indian owned food-based companies to alter their products to fit a larger market, while responding to the demands of a rapidly modernizing society
Optimization of CO2 production rate for firefighting robot applications using response surface methodology
No full textA carbon dioxide gas-powered pneumatic actuation has been proposed as a suitable power source for an autonomous firefighting robot (CAFFR), which is designed to operate in an indoor fire environment in our earlier study. Considering the consumption rate of the pneumatic motor, the gas-powered actuation that is based on the theory of phase change material requires optimal determination of not only the sublimation rate of carbon dioxide but also the sizing of dry ice granules. Previous studies that have used the same theory are limited to generating a high volume of carbon dioxide without reference to neither the production rate of the gas nor the size of the granules of the dry ice. However, such consideration remains a design requirement for efficient driving of a carbon dioxide-powered firefighting robot. This paper investigates the effects of influencing design parameters on the sublimation rate of dry ice for powering a pneumatic motor. The optimal settings of these parameters that maximize the sublimation rate at the minimal time and dry ice mass are presented. In the experimental design and analysis, we employed full-factorial design and response surface methodology to fit an acceptable model for the relationship between the design factors and the response variables. Predictive models of the sublimation rate were examined via ANOVA, and the suitability of the linear model is confirmed. Further, an optimal sublimation rate value of 0.1025 g/s is obtained at a temperature of 80°C, the mass of 16.1683 g, and sublimation time of 159.375 s
Chemical Constituents and Antimicrobial Activity of Essential Oils from Micropropagation and Field-Grown Plants of Wedelia biflora [L.]
No full textAn efficient regeneration protocol through axillary and inter nodal explants was developed from Wedelia biflora. Explants were placed on MS medium supplemented with different treatments of cytokinins, 6-benzyladenine (BA) and kinetin (KIN) for adventitious shoot production. The highest multiple shoots (95 %; 26.4 shoots/ explant) and elongation (2.75 cm shoot length), was obtained in 1.0 BA mg L -1 in axillary node explants. The shoot was transferred to half-strength MS medium supplemented with 2.0 mg L -1 IBA showed the best root formation (85 %; 22.2 roots/shoot; 2.65 cm root length; propagate leaf d.w 1.42 g L -1 and root d.w 1.10 g L -1 ) and plantlets were successfully acclimatized in the green house. The compositions of essential oils were studied in in vitro and in vivo leaf explants and to determine their absolute and relative concentrations using GC-MS and GC-FID, respectively. In vitro and in vivo variations in composition among the essential oils were detected. Sesquiterpene and monoterpene are major components in the oil of in vitro and in vivo leaves of W. biflora. Essential oil quantification showed α-pinene (44.03 %); verbenone (15.37 %); δ-cadinene (5.48 %) of in vivo leaves; whereas α-pinene (5.02 %); verbenone (1.40 %) and δ-cadinene (3.13 %) of in vitro leave respectively. The in vitro and in vivo essential oils were analyzed by bacterial and fungal organism through disc diffusion and minimum inhibitor concentration (MIC) methods. The results were compared with reference drugs ciprofloxacin and nystatin respectively. In vitro developed plants exhibited higher sesquiterpene contents and antimicrobial activity than field grown plant
Chitosan capped nickel oxide nanoparticles as a saturable absorber in a tunable passively Q-switched erbium doped fiber laser
No full textNickel oxide (NiO) nanoparticles successfully prepared from a nickel(ii) chloride hexahydrate precursor are used to form a chitosan capped NiO nanoparticle thin film to serve as a saturable absorber (SA) for the generation of passively Q-switched pulses in an erbium doped fiber laser (EDFL). The NiO/chitosan SA based EDFL is able to generate stable pulsed outputs at a low threshold pump power of 104.90 mW with a central wavelength at 1562 nm. The highest pulse energy obtainable by the system is 15.30 nJ at a repetition rate of 42.66 kHz and a pulse duration of 2.02 μs. The laser has a spectral range of 58 nm from 1522 to 1580 nm, covering the C and L bands and even portions of the S band. This study experimentally demonstrates that the potential of the NiO/chitosan film as an SA material for Q-switching operations, combined with the biocompatibility, non-toxicity and high thermal resistance of Chitosan, holds great prospects for a broad range of applications
Effects of process parameters on the properties of brake pad developed from seashell as reinforcement material using grey relational analysis
No full textOver the years, asbestos was used as reinforcement material in brake pads production. However, due to its carcinogenic nature, it has lost its favor and there is need to find an alternative material. In this study, brake pads were produced from locally sourced non-hazardous raw materials using grey relational analysis. The materials used for production include seashell, epoxy resin (binder), graphite (friction modifier) and aluminum oxide (abrasive). Twenty- seven different samples were produced using seashell as reinforcement material by varying the process parameters. Rule of mixture was used for formulation and a weight percent of 52% reinforcement, 35% binder, 8% abrasive and 5% friction modifier were used for production. Grey relational analysis was conducted in order to scale the multi-response performance to a single response. The results indicate that optimum performance can be achieved with 14 MPa molding pressure, 160 °C molding temperature, 12 min curing time and 1 h heat treatment time. Analysis of variance shows that curing time has the least significant effect on the mechanical properties, while curing time of 24.26% and 55.23% has the most significant effect on coefficient of friction and wear rate respectively on the brake pad developed
Predicting sanitary landfill leachate generation in humid regions using ANFIS modeling
No full textLandfill leachate is one of the sources of surface water pollution in Selangor State (SS), Malaysia. Leachate volume prediction is essential for sustainable waste management and leachate treatment processes. The accurate estimation of leachate generation rates is often considered a challenge, especially in developing countries, due to the lack of reliable data and high measurement costs. Leachate generation is related to several variable factors, including meteorological data, waste generation rates, and landfill design conditions. Large variations in these factors lead to complicated leachate modeling processes. The aims of this study are to determine the key elements contributing to leachate production and then develop an adaptive neural fuzzy inference system (ANFIS) model to predict leachate generation rates. Accuracy of the final model performance was tested and evaluated using the root mean square error (RMSE), the mean absolute error (MAE), and the correlation coefficient (R). The study results defined dumped waste quantity, rainfall level, and emanated gases as the most significant contributing factors in leachate generation. The best model structure consisted of two triangular fuzzy membership functions and a hybrid training algorithm with eight fuzzy rules. The proposed ANFIS model showed a good performance with an overall correlation coefficient of 0.952
Operating continuity insurance of electric vehicle by using fault-tolerant control of 7-leg inverter
No full textIn this paper, a new fault-tolerant control (FTC) is applied to a 7-leg inverter pulse width modulation (PWM) to control dual induction motors (IMs) driving two electric-vehicle (EV) wheels. This FTC maintains the continuity of operation case of the fault the same as in pre-fault. In a faulty condition, two legs are added to the normal condition configuration and both are connected to the IM neutrals through other switches. Therefore, the added legs are activated only when the fault has occurred. This topology allows minimizing the power switches; thus, weight, size and cost of the vehicle architecture are optimized. In this work, the fault is assumed to be known a priori and the focus is on the remedial actions upon fault occurrence. The proposed FTC is based on a PWM control strategy in parallel to independent control. It reduces power switch failure within the control system and allows a reconfigurable topology that keeps the EV performance in faulty conditions as similar as in the case of normal conditions. Experiments and simulations, regarding IMs drive on an EV, are carried out using the European urban driving cycle to demonstrate the behaviour of the suggested FTC, which provides the same performance as the pre-fault case
The Response of Macrobenthic Communities to Environmental Variability in Tropical Coastal Waters
No full textThe relative contributions of spatial and temporal fluctuations are different in shaping natural communities in a tropical coastal/estuarine system. Understanding how coastal communities respond to these fluctuations is still equivocal, and thus, available data are rare. Here, multiple analytical approaches were used to identify key spatial and temporal factors, and to quantify their relative roles in shaping a macrobenthic community through space (contamination degree, physical parameters, and sediment characteristics) and time (climatic factors, season, and year). A dataset of eight sampling times was analyzed over a period of 2 years, in which macrobenthic species abundances were sampled. A total of 33 species were identified, including 18 bivalves, 5 gastropods, and 4 crustaceans. The other taxa were less diverse. The results show that there were no significant temporal changes of macrobenthic community structure, but spatial changes were significant and synchronized with environmental factors (i.e., sediment characteristics, water depth, and the distance from anthropogenic sources). This study demonstrates that spatial factors played a primary role in structuring of macrobenthic assemblages, whereas the influence of temporal factors appeared less across geographically distinct sites. Thus, temporal variation of a coastal macrobenthic community appears to be controlled by partly different processes at different scales
Reservoir operation based on evolutionary algorithms and multi-criteria decision-making under climate change and uncertainty
No full textThis study investigated reservoir operation under climate change for a base period (1981-2000) and future period (2011-2030). Different climate change models, based on A2 scenario, were used and the HAD-CM3 model, considering uncertainty, among other climate change models was found to be the best model. For the Dez basin in Iran, considered as a case study, the climate change models predicted increasing temperature from 1.16 to 2.5°C and decreasing precipitation for the future period. Also, runoff volume for the basin would decrease and irrigation demand for the downstream consumption would increase for the future period. A hybrid framework (optimization-climate change) was used for reservoir operation and the bat algorithm was used for minimization of irrigation deficit. A genetic algorithm and a particle swarm algorithm were selected for comparison with the bat algorithm. The reliability, resiliency, and vulnerability indices, based on a multi-criteria model, were used to select the base method for reservoir operation. Results showed the volume of water to be released for the future period, based on all evolutionary algorithms used, was less than for the base period, and the bat algorithm with high-reliability index and low vulnerability index performed better among other evolutionary algorithms