Browse publications by year: 2016

  1. Zeng Zhou Tan, Mohammad Zakir Hossain, Md Shahidul Ahsan, Yew Choy Chew, Swe Swe Win, Suan Phaik Khoo
    Sains Malaysiana, 2016;45:201-205.
    Angiogenesis has an important role in the invasion, metastasis and growth of tumors. Increased microvessel density (MVD) has been described in oral squamous cell carcinoma (OSCC) compared to oral dysplasia and normal oral tissue. A morphometric study was designed to evaluate the MVD and to evaluate the presence of any association between MVD and keratin pearl in the three histopathological grades of OSCC (as defined in Bryne’s grading system). Forty-five samples of OSCC were graded into well differentiated (WDSCC), moderately differentiated (MDSCC) and poorly-differentiated (PDSCC) oral squamous cell carcinoma. Morphometric analysis showed that MVD was significantly lower in WDSCC compared to MDSCC (p<0.001) and PDSCC (p<0.001). The density in MDSCC was significant lower than PDSCC. The keratin pearl count was significantly higher in WDSCC compared to MDSCC (p<0.001) and PDSCC (p<0.001). Between MDSCC and PDSCC, the keratin pearl count was significantly higher for MDSCC (p=0.001). Pearson correlation test showed a significant negative correlation between keratin pearl and MVD (r=-0.805, p<0.001). The findings suggested that vascularity in OSCC is associated with its cellular differentiation and also associated with keratin pearl formation.
  2. Abdul Ghani Rafek, Azimah Hussin, Lee KE, Ailie Sofyiana Serasa, Goh TL
    Sains Malaysiana, 2016;45:185-193.
    The uniaxial compressive strength (UCS) is one of the most common mechanical parameters required in geotechnical engineering to characterize the compressive strength of rock material. Measurements of UCS are expensive, time consuming, destructive and thus, not favorable in the presence of limited samples. Therefore, a simple yet practical application is needed for the estimation of UCS. This research presents two correlations to predict UCS values for granite and schist by using ultrasonic velocity travel time (tp) from ultrasonic tests. The validity of the practical approach presented in this research is confirmed based on the strong correlations developed from the experimental tests conducted. For the entire data set, the correlation between UCS and ultrasonic velocity travel time was expressed as UCS = 217.2 e-0.016(tp) for granite and UCS = 1110.6 e-0.037(tp) for schist and the coefficient of determination (R2) value for both granite and schist is 0.93. These correlations may be useful for applications related to geotechnical engineering designs.
    MeSH terms: Aggression; Engineering; Research; Silicon Dioxide; Ultrasonics; Compressive Strength
  3. Ghulam Hasan Abbasi, Javaid Akhtar, Muhammad Anwar-ul-haq, Moazzam Jamil, Shafaqat Ali, Rafiq Ahmad, et al.
    Sains Malaysiana, 2016;45:177-184.
    Effects of NaCl salinity and cadmium on the anti-oxidative activity of enzymes like superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), glutathione reductase (GR) and lipid peroxidation contents; malondialdehyde (MDA) were studied in two maize hybrids of different salt tolerance characteristics. An increase in the amount of lipid peroxidation indicated the oxidative stress induced by NaCl and Cd. The results also depicted that NaCl stress caused an increase in the activities of POD, SOD, CAT, APX and GR while cadmium stress increased the activities of POD, SOD and APX but showed no significant effect on CAT and GR in both the studied hybrids. The combined effect of salinity and cadmium on these parameters was higher than that of sole effect of either NaCl or Cd. It was also found that maize hybrid 26204 had better tolerance against both stresses with strong antioxidant system as compared to that of maize hybrid 8441. A comparison of the antioxidants and lipid peroxidation in two maize hybrids having varying level of NaCl and Cd stress tolerance corroborated the importance of reactive oxygen species (ROS) in defense against abiotic stresses.
    MeSH terms: Antioxidants; Cadmium; Catalase; Zea mays; Glutathione Reductase; Malondialdehyde; Peroxidase; Peroxidases; Superoxide Dismutase; Lipid Peroxidation; Reactive Oxygen Species; Oxidative Stress; Salinity; Salt-Tolerance; Ascorbate Peroxidases
  4. Jehan Bakht, Laleena Khan, Mohammad Shafi
    Sains Malaysiana, 2016;45:167-176.
    The present study investigates heavy metal uptake and protein expression by different vegetables collected from various districts of Khyber Pakhtunkhawa province of Pakistan. Statistical analysis of the data showed that maximum concentration of Cd, Cr, Ni, Zn were found in radish and spinach, respectively, collected from Peshawar. Maximum Pb and Mg accumulation were found in cauliflower and pea at Swat followed by coriander at Haripur and minimum Pb uptake was noticed in radish taken from Nowshehra. Highest Cu uptake was detected in spinach at Nowshehra. Data regarding Cd, Cr, Pb, Cu, Ni, Mg and Zn concentration in water samples gathered from different sites of KPK indicated that maximum concentration of Cd was observed in Swat. Maximum Cr and Cu concentration were measured in water samples from Peshawar while maximum concentration of Pb and Ni were detected in water samples from Haripur. In case of soil samples, maximum Cd, Cr, Mg and Zn uptake was observed in soil sample at Nowshehra. Maximum Pb and Ni concentration was found in soil samples collected from Peshawar. Cu concentration was observed to be the highest in soil at Swat. Protein profile of different vegetables i.e. cauliflower, radish, carrot, turnip, pea, spinach, coriander and garlic sampled across five different sites showed that uptake of Cd, Cr, Pb, Cu, Ni, Mg and Zn by these vegetables caused the expression of numerous polypeptides.
    MeSH terms: Brassica; Garlic; Lead; Pakistan; Peptides; Soil; Vegetables; Zinc; Peas; Daucus carota; Spinacia oleracea; Metals, Heavy; Coriandrum; Brassica napus; Raphanus
  5. Ling Ty, Lee Nyanti, Theresa Muan, Jongkar Grinang, Siong-fong Sim, Aazani Mujahid
    Sains Malaysiana, 2016;45:157-166.
    Determining the water quality of Bakun Reservoir 13 months after it operates at full supply level is crucial for better understanding of changes in the physicochemical parameters, which may enable the prediction of its effects on the survival of aquatic life in the reservoir. This study determined 13 physicochemical parameters at six stations within the reservoir at fixed depths. The results showed that the minimum 5 mg/L of dissolved oxygen (DO) required for sensitive aquatic organisms was recorded at 6 m depth. However, DO was not detectable at depths exceeding 7 m. The water was acidic at depths of more than 10 m. Turbidity and total suspended solids increased corresponding with depth. Inorganic nitrogen were predominantly in the form of ammonia-nitrogen, creating an unhealthy environment for aquatic life. Concentration of Chl-a was significantly higher at the subsurface water than 30 m depth in four out of six stations. The present study shows changes in water quality as compared to the pre-impounded period and 15 months after the filling phase, in particular, stratification of dissolved oxygen, thermocline conditions and alkalinity. The changes varied according to the distance from the dam and may have been influenced by existing land developments within the area such as the construction of the Murum Hydroelectric Dam, oil palm plantations and timber concessionares. Though the water quality might have deteriorated, further study is needed to determine if this condition will prolong.
    MeSH terms: Ammonia; Environment; Nitrogen; Oxygen; Water; Life; Aquatic Organisms; Water Quality
  6. Nor Hafizah Zakaria, Mohammad Mustafizur Rahman, Ahmed Jalal Khan Chowdhury, Zaima Azira Zainal Abidin
    Sains Malaysiana, 2016;45:135-140.
    The application of microbial techniques in aquaculture has been playing a vital role to increase the production yield by improving the nutritional values of the targeted fish. Phototrophic purple bacteria as single cell protein (SCP) appears to be a promising substitution for protein rich supplement for aquaculture feeds making them a promising growth enhancer in aquaculture industry. Two species of phototrophic purple bacteria, Marichromatium sp. and Rhodopseudomonas sp. were used in the commercial diet to compare the growth, survival rate and feed utilizationon for Tor tambroides juvenile. Purple bacteria were isolated from mangrove sediment and fish tank and mass cultured using 112 synthetic media under anaerobic light condition. Bacterial cells were included in the diets by mixing the fresh biomass with the crushed commercial pellet, re-pelleted and air-dried. The experimental diets were fed to the fingerlings twice per day for 10 weeks to satiation level. The results showed that there were trends of increased growth, better survival rate and improved feed conversion ratio when fed with diet 1 (Marichromatium sp.) compared with other diets. There was significant difference (p<0.05) between the sampling days. The specific growth rate and weight gain of the fish fed with diet 1 were 0.49 % and 4.92 g, respectively, compared to 0.42% and 4.11 g from the control. This study suggested that purple bacteria could be used in feed formulation as a supplement to promote growth and survival of freshwater fishes in Malaysia.
    MeSH terms: Animals; Diet; Dietary Proteins; Fishes; Fresh Water; Malaysia; Nutritive Value; Rhodopseudomonas; Satiation; Spores, Bacterial; Weight Gain; Survival Rate; Aquaculture; Biomass; Proteobacteria
  7. Huixing Liang, Aihui Chen, Zhaoxia Li, Muhammad Aqeel Ashraf, Cheng Ding
    Sains Malaysiana, 2016;45:129-134.
    In order to explore the response of the soil microbial community to 1,2-dichlorobenzene exposure in Wetland soil, a short-term (7 weeks) mesocosm study was conducted at four 1,2-dichlorobenzene concentrations of (100, 400 and 800) μg g -1. Dry soil, sterile and unsterile controls were also compared. The results obtained showed a significant effect of 1,2-dichlorobenzene on the development of bacterial populations in soils contaminated with different concentrations of 1,2-dichlorobenzene at the early time after application. In general, however, the number of populations of the same soil sample treated with the same concentration of 1,2-dichlorobenzene differed significantly with the increasing incubation time within the early 5 weeks. The scale of differences in banding patterns-showed that the microbial community structures of 1,2-dichlorobenzene-treated and non-1,2-dichlorobenzene-treated soils were not significantly different after 7 weeks of incubation. DNA in application-responsive bands from the 1,2-dichlorobenzene treatments was recovered and amplified using the universal primers. PCR products were recovered and cloned into pGEM-T Easy (Promega) and two clones were obtained. The two clones were sequenced using the automated Model 3730 DNA sequencing system. The two cloned sequences had very high similarities to an uncultured bacterium reported previously in the database of NCBI.
  8. Mohammed A. Jasim, Mohd Sofian-azirun, Yusoff, Motior Rahman M
    Sains Malaysiana, 2016;45:119-127.
    In this paper we have studied the acute toxicity effect of Hg on hybrid tilapia (Oreochromis niloticus). For this, the tissues of tilapia have been digested by means of acids in microwave oven and was analyzed by flameless atomic absorption spectrophotometer (FAAS). We have identified that the levels of Hg varied significantly in different tissues and the metal concentration was in the following order: liver > gills > muscles; of which the maximum level recorded for Hg was 0.799 mg/kg. We have also observed the alterations towards histopathological aspects in the gills and liver of treated fishes were studied using light and electron microscopy, subjected to the exposure of Hg for 24 h and furthermore we have also noticed the extent of the increased alterations during the 96 h of exposure to median lethal concentration LC50 (0.3 mg/L) a severe disorganization of epithelial cells and modifications of the structure of the secondary lamellae. Moreover the severity has also found to increase to sub-lethal concentration (0.03 mgHg/L) in 21 days of exposure; Liver was slightly affected by the contamination of Hg. Ultimately, histopathology is considered as a sensitive technique of bioaccumulation and for the observing the potential damage from Hg exposure.
    MeSH terms: Animals; Epithelial Cells; Gills; Liver; Mercury; Microscopy, Electron; Microwaves; Muscles; Spectrophotometry, Atomic; Tilapia; Cichlids
  9. Tang Mei, Liu Cao, Liang Zi, Hu Die, Gong Mingfu
    Sains Malaysiana, 2016;45:115-118.
    In order to separate lumbrokinase in Pheretima praepinguis and to study the enzymatic properties, with Pheretima praepinguis as material, lumbrokinase was separated with the salting out method. Lumbrokinase activity was measured with casein medium plate method. The effect of pH and temperature on lumbrokinase activity was studied. The activity of lumbrokinase separated from Pheretima praepinguis was relatively high. Lumbrokinase activity in neutral or slightly alkaline environment was higher. Lumbrokinase had tolerance ability to high temperature, with highly enzymatic activity under 60° and wide range of temperature adaptation.
  10. Xu-hui Zhang, Lei Liang, Xiao-yan Wang, Li Zhang, Yan-xin Zheng, Hong-zhu Deng, et al.
    Sains Malaysiana, 2016;45:109-113.
    We investigated the antitumor effects of the combination of matrine-a purified alkaloid extracted from Sophora flavescence-and 5-fluorouracil (5-FU) on SW480 cells. This combination inhibited the growth of SW480 cells in a synergistic or additive manner by disrupting their progression through the cell cycle. Exposure of SW480 cells to matrine and 5-FU was followed by an increased rate of expression for caspase-3, caspase-9 and poly-ADP ribose polymerase (PARP) and inhibited the subcutaneous transplantation of SW480 tumors into Balb/c nude mice. Histopathological analysis showed that this effect was most pronounced in the spleens of treated animals. Typical cytotoxic effects observed in 5-FU-treated mice included fibrosis and lymphopenia, whereas in mice treated with 5-FU combined with matrine, the spleen ultrastructure remained intact. These findings indicate that matrine may enhance the therapeutic effectiveness of 5-FU in SW480 tumors by enhancing apoptosis and overcome the threat to immunocompetence associated with 5-FU.
    MeSH terms: Adenosine Diphosphate Ribose; Alkaloids; Animals; Cell Cycle; Fluorouracil; Immunocompetence; Lymphopenia; Mice, Nude; Neoplasms; Poly(ADP-ribose) Polymerases; Quinolizines; Spleen; Apoptosis; Sophora; Mice; Caspase 3; Caspase 9; Poly (ADP-Ribose) Polymerase-1
  11. Liu Hui
    Sains Malaysiana, 2016;45:99-107.
    Investigation of meteorological disasters caused by small-scale topography shows that flashover due to wind age yaw occurred quite often where col topography existed. Considering that the distribution pattern of wind profile at different locations of a col topography is not clear, this paper, with wind tunnel tests, studied the influenced of such topographic features of a col as hill slope and valley mouth width on the wind profile at different locations. The results of wind tunnel tests indicated that over-hill wind has a stronger effect on wind velocity correction coefficient than does valley wind, that compared to flat terrain wind velocity, the maximum speed-up amplitude of wind velocity at valley throat and hill summit reach 33 and 53%, respectively, apparently higher than 10% specified in Codes, that wind velocity at valley throat increases with the increase of hill slope and decreases with the increase of valley mouth width, that wind velocity in the valley basically does not go up when the slope of one hill side is smaller than 0.1 and that wind velocity at the same non-dimensional height of a 3D hill summit increases with the increase of hill height.
    MeSH terms: Disasters; Mouth; Neck; Pharynx; Wind; Meteorology
  12. Zulkifli Yusop, Harisaweni, Fadhilah Yusof
    Sains Malaysiana, 2016;45:87-97.
    Rainfall intensity is the main input variable in various hydrological analysis and modeling. Unfortunately, the quality of rainfall data is often poor and reliable data records are available at coarse intervals such as yearly, monthly and daily. Short interval rainfall records are scarce because of high cost and low reliability of the measurement and the monitoring systems. One way to solve this problem is by disaggregating the coarse intervals to generate the short one using the stochastic method. This paper describes the use of the Bartlett Lewis Rectangular Pulse (BLRP) model. The method was used to disaggregate 10 years of daily data for generating hourly data from 5 rainfall stations in Kelantan as representative area affected by monsoon period and 5 rainfall stations in Damansara affected by inter-monsoon period. The models were evaluated on their ability to reproduce standard and extreme rainfall model statistics derived from the historical record over disaggregation simulation results. The disaggregation of daily to hourly rainfall produced monthly and daily means and variances that closely match the historical records. However, for the disaggregation of daily to hourly rainfall, the standard deviation values are lower than the historical ones. Despite the marked differences in the standard deviation, both data series exhibit similar patterns and the model adequately preserve the trends of all the properties used in evaluating its performances.
    MeSH terms: Electrocardiography; Heart Rate; Reproducibility of Results; Models, Statistical; Hydrology
  13. Amira FS, Kamaruzzaman BY, Jalal KCA, Rahman MM, Hossain MY, Khan NS
    Sains Malaysiana, 2016;45:79-86.
    A study was conducted to understand the relative abundance and growth of male and female Nemipterus furcosus population in the Pahang coastal water, Malaysia. The sampling was done monthly for a period of one year. A total of 1446 fish specimens were studied in this research. The results showed that male N. furcosus population was significantly more than female (p<0.01) N. furcosus population. The growth coefficient (b value) varied between 2.6808 and 3.2396 for male and 2.0926 and 3.2838 for female N. furcosus. The growth co-efficients of male N. furcosus were significantly different than the growth co-efficients of female N. furcosus in all months (p<0.05). They showed negative allometric growths in February- June and September. Female N. furcosus showed positive allometric growths in November-January and August. Isometric growths of female were observed only in October and July. As for male N. furcosus, negative allometric growths were observed in March-June, November and January. Male N. furcosus showed positive allometric growths in August, September, October, December and February. Male N. furcosus showed isometric growth only in July. The overall mean condition factor of male and female was statistically similar (p>0.05). The condition factor (K) ranged from 1.2559 to 1.3917 for male while 1.2503 to 1.3926 for female N. furcosus. Overall, higher mean condition factor was observed in smaller fish of both sexes. This study is useful for policy makers and fishery biologists for sustainable fishery management in the Pahang coastal water, Malaysia.
    MeSH terms: Animals; Female; Fisheries; Fishes; Malaysia; Male; Men; Research; Sexual Behavior
  14. Sumaira Naeem, Muhammad Aqeel Ashraf, Misni Bin Misran, Lik Voon Kiew, Lip Yong Chung
    Sains Malaysiana, 2016;45:71-77.
    The aimed of the present study was to evaluate the liposomal formulation regarding its hydrophobicity. The evaluation studies were done based on the amphiphilic nature of the phospholipid liposomes. This paper highlights the importance of such type of lipid based carriers by encapsulation hydrophobic and hydrophilic drug models. Crystal violet and Nile red were used to represent hydrophilic and hydrophobic moieties before moving to pharmaceutical implications. The formulated liposomes were compared for their hydrophobicity using percent encapsulation efficiencies. The purpose of this formulation was to mimic the red blood cells. The average particle size of 120±25.1 and zeta potential of -10.2±1.4 were in good agreement with reported characteristics of the red blood cells. Per cent encapsulation efficiency for crystal violet was more obvious with a value of 68.1 as compared to 36.5% for Nile red. The prepared liposomes were quite stable for a period of one month. Our findings reflect the fate of our system more suitable for hydrophilic drugs under the given set of formulation parameters.
  15. Radaideh JA, Alazba AA, Amin MN, Shatnawi ZN, Amin MT
    Sains Malaysiana, 2016;45:59-69.
    Indoor air quality assessment in residential areas of Al-Hofuf city/Eastern region of Saudi Arabia is investigated through a multi-week multiple sites sampling survey. Critical air pollution indicators, including nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), carbon dioxide (CO2) and total volatile organic compounds (TVOC) as well as temperatures were measured and analyzed during the study period from January to May 2014. Three site-types - roadside, urban and rural - were selected and within each site type, six locations were selected to study the varying indoor/outdoor air quality. The results indicated that NO2 and CO concentrations increased at the starting hours of the day. SO2 concentrations were relatively low and constant. In addition, a strong association between outdoor and indoor air quality was found. Measurements showed that indoor/outdoor ratio for TVOC ranged from 0.8 to 0.99. For CO2, NO2 and SO2, this was 0.92-1.15, 0.5-0.7 and 0.52-0.9, respectively. Finally, the effects of activated carbon (AC) were investigated to assess the extent of the improvement in the indoor air quality. The analysis of data obtained indicated that using locally prepared AC from date stones was an effective way to reduce the indoor air pollution with an overall efficiency of 85.5, while the use of industrial granular AC reduced the air pollutants with an efficiency of less than 0.6. In addition, AC was exposed to an exhaust gas flow to evaluate its elimination potential for high concentrated pollutants. The obtained results demonstrated that AC was also functioning as an efficient absorbent with an overall removal efficiency of 77.8%, even when it was exposed to high concentrations.
    MeSH terms: Air Pollutants; Air Pollution; Vehicle Emissions; Carbon; Carbon Dioxide; Carbon Monoxide; Cities; Housing; Nitrogen Dioxide; Surveys and Questionnaires; Saudi Arabia; Sulfur Dioxide; Temperature; Air Pollution, Indoor; Volatile Organic Compounds
  16. Wang Yan-feng, Ma Ning
    Sains Malaysiana, 2016;45:55-58.
    Hosoya and Merrifield-Simmons index were the two valuable topological indices in chemical graph theory. The Hosoya and Merrifield-Simmons index of the class of unicyclic graphs G(k) were investigated, according to the distance between u and v on Cm, their orderings with respect to these two topological indices were obtained.
    MeSH terms: Algorithms; Anatomy, Regional; Computer Graphics
  17. Nor Bakhiah Baharim, Ismail Yusoff, Wan Zakaria Wan Muhd Tahir, Muhamad Askari, Zainudin Othman, Mohamed Roseli Zainal Abidin, et al.
    Sains Malaysiana, 2016;45:43-53.
    The relationship between heavy metal and trophic properties in polymictic lake at Sembrong Lake, Peninsular Malaysia was assessed. Sixteen parameters, including heavy metals and trophic parameters were monitored. pH, temperature, dissolved oxygen and heavy metals level changes significantly influenced by the dynamic of polymictic mixing pattern. The mean concentrations of heavy metals in the reservoir decreased in the following order: Fe > Mn > Zn > Cu > As > Pb. The result showed that this polymictic lake is being threatened by cultural eutrophication with TSI value range from 72.40 to 80.41 and classified as a hypereutrophic lake. The levels of heavy metal pollution in the reservoir range from slightly polluted to polluted. Factor analysis was performed to determine the relationship between heavy metals and trophic parameters. Five factors were responsible for data structure and explained the 83% of total variance. These factors differentiate each group of parameters according to their common characteristics. Photosynthesis, respiration and redox processes were main factors contributing to the variability of both properties.
    MeSH terms: Eutrophication; Factor Analysis, Statistical; Factor V; Lead; Malaysia; Oxidation-Reduction; Oxygen; Photosynthesis; Temperature; Zinc; Metals, Heavy; Lakes
  18. Insheng Zhao, Na Zhang, Minghua Zhou
    Sains Malaysiana, 2016;45:35-41.
    The sewage irrigation area in Tianjin reached 6 billion m2 in 2003 which accounts for 22% of the irrigated areas. Polycyclic aromatic hydrocarbons (PAHs) contamination caused by sewage irrigation on agricultural land has attracted considerable attention because of their toxic and hazardous risks to human beings. In order to evaluate the health risk of PAHs to farmers in four age groups, a multimedia/multipathway exposure model was applied. The results showed that the chronic daily intake (CDI) of children, adolescents, adults and the aged to the 16 PAH compounds exposure were 2.83, 2.34, 1.44, 1.05 μg·kg-1·d-1, respectively. The non-cancer risk of life long exposure in sewage irrigation was 2.75×10-3 and the cancer risk was 2.49×10-5. From the long-term safety point of view, the health risks caused by PAHs were at a relatively high level. Hence, we suggest that crops of sewage irrigated areas and their distribution channels should be re-concerned by the government in the future city planning.
  19. Chin AB, Sepehr Talebian, Umma Habiba, Amalina M. Afifi
    Sains Malaysiana, 2016;45:29-34.
    In this study, the effect of hydrolysis on electrospinnability of chitosan/PVA blend solution has been investigated. Since crude chitosan (Mw=8.96105 g/mole, DD=40%) could not be dissolved even in concentrated acetic acid, it was hydrolyzed with 33.5 wt. % of NaOH at 90°C for 24 and 42 h. Hydrolyzed chitosan with two different time duration was analyzed using Fourier transform infrared (FTIR). Morphology of the product nanofiber was investigated by field emission scanning electron microscope (FESEM.). FTIR results showed that the hydrolysis did not destroy the molecular backbone of chitosan but increased the degree of deacetylation from 40 to 84% and 92% for 24 and 42 h hydrolysis time, respectively. FESEM image analysis was carried out and histogram was drawn to study on the distribution of fiber diameter. It showed that though the composition of chitosan/PVA remained the same, but mean fiber diameter, standard deviation and required applied voltage for electrospinning was smaller for the solution containing maximum time hydrolyzed chitosan. It indicated that longer hydrolysis time resulted in finer nanofiber which mostly attributed to lower required voltage for electrospinning. Threshold composition for defect free fiber is 50:50 and 60:40 of chitosan/PVA for 24 and 42 h hydrolysis, respectively. It meant that 42 h hydrolysis ensured the presence of more chitosan in the chitosan/PVA polymer blend because of smaller presence of amino group in chitosan molecule.
  20. Mahmoud khaki, Ismail Yusoff, Nur Islami, Nur Hayati Hussin
    Sains Malaysiana, 2016;45:19-28.
    Forecasting of groundwater level variations is a significantly needed in groundwater resource management. Precise water level prediction assists in practical and optimal usage of water resources. The main objective of using an artificial neural network (ANN) was to investigate the feasibility of feed-forward, Elman and Cascade forward neural networks with different algorithms to estimate groundwater levels in the Langat Basin from 2007 to 2013. In order to examine the accuracy of monthly water level forecasts, effectiveness of the steepness coefficient in the sigmoid function of a developed ANN model was evaluated in this research. The performance of the models was evaluated using the mean squared error (MSE) and the correlation coefficient (R). The results indicated that the ANN technique was well suited for forecasting groundwater levels. All models developed had shown acceptable results. Based on the observation, the feed-forward neural network model optimized with the Levenberg-Marquardt algorithms showed the most beneficial results with the minimum MSE value of (0.048) and maximum R value of (0.839), obtained for simulation of groundwater levels. The present research conclusively showed the capability of ANNs to provide excellent estimation accuracy and valuable sensitivity analyses.
    MeSH terms: Algorithms; Forecasting; Research; Colon, Sigmoid; Water; Neural Networks (Computer); Groundwater; Water Resources
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