Metal concentrations in Sungai Sedili Kecil, Johor, Peninsular Malaysia

Water and sediment from five sampling stations in Sungai Sedili Kecil were sampled in October 2010 and analyzed for 11 metals including cadmium (Cd), copper (Cu), manganese (Mn), iron (Fe), lead (Pb), aluminium (Al), zinc (Zn), nickel (Ni), cobalt (Co), arsenic (As) and argentum (Ar). Results showed that the mean dissolved metal concentrations (in μg/L) in Sungai Sedili waters based on 5 sampling stations (in descending order) for Fe, Al, Zn, Cu, As, Mn, Ni, Pb, Co, Cd and Ag were 443.7, 52.7, 50.2, 34.2, 25.9, 20.3, 6.8, 1.4, 0.77, 0.67 and 0.10 μg/L, respectively. Mean metal concentrations (in μg/g dry weight) for sediments (in descending order) for Fe, Al, Mn, Zn, Pb, Cu, As, Ni, Co, Cd and Ag were 33389.4, 17118.7, 190.5, 55.1, 29.1, 26.3, 19.3, 10.9, 4.7, 0.18 and 0.12 μg/g, respectively. A comparison with various water and sediment quality standards showed that the mean metal concentrations in surface water and sediment of Sungai Sedili Kecil were low and within the range of natural background except for Cu and Fe in water

Use of multispecies freshwater biomonitor (MFB) to assess behavioral changes of guppy poecilia reticulata and freshwater prawn macrobrachium lanchesteri in response to cadmium

The Multispecies Freshwater Biomonitor¨ (MFB) uses the measurement and analysis of different types of behaviours from different aquatic organisms for monitoring the water quality in freshwater ecosystem. The aim of this study was to determine the specific response of freshwater shrimp (Macrobrachium lanchesteri) and guppy fish (Poecilia reticulata) to cadmium (Cd) in the laboratory. Different concentrations of Cd were exposed to M. lanchesteri (1 ppb and 10 ppb) and P. reticulata (100 ppb and 560 ppb) and the behavioural changes of the organisms were recorded by MFB for 2 hours. Results showed that the behavioural and ventilation response of M. lanchesteri and P. reticulata increased with increasing exposure concentrations of Cd. Results also showed that the shrimp was more sensitive to Cd than the guppy fish and these local species were suitable as indicator organism for the MFB

Toxicity of Metals to a Freshwater Snail, Melanoides tuberculata

Adult freshwater snails Melanoides tuberculata (Gastropod, Thiaridae) were exposed for a four-day period in laboratory conditions to a range of copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb), nickel (Ni), iron (Fe), aluminium (Al), and manganese (Mn) concentrations. Mortality was assessed and median lethal times (LT50) and concentrations (LC50) were calculated. LT50 and LC50 increased with the decrease in mean exposure concentrations and times, respectively, for all metals. The LC50 values for the 96-hour exposures to Cu, Cd, Zn, Pb, Ni, Fe, Al, and Mn were 0.14, 1.49, 3.90, 6.82, 8.46, 8.49, 68.23, and 45.59 mg L−1, respectively. Cu was the most toxic metal to M. tuberculata, followed by Cd, Zn, Pb, Ni, Fe, Mn, and Al (Cu > Cd > Zn > Pb > Ni > Fe > Mn > Al). Metals bioconcentration in M. tuberculata increases with exposure to increasing concentrations and Cu has the highest accumulation (concentration factor) in the soft tissues. A comparison of LC50 values for metals for this species with those for other freshwater gastropods reveals that M. tuberculata is equally sensitive to metals

Impact of Electron Radiation Dose to the Performance of Half-Wave Rectifier and Converter Circuits with Silicon Carbide Schottky Diode

Half-wave rectifier; buck; and boost converter with electron-irradiated, high-voltage silicon carbide Schottky power diodes from CREE, Inc., performance were studied and presented in this paper subjected to electron radiation. The diodes were irradiated by high-energy (3 MeV) electrons with doses ranging from 1 to 5 MGy. The performance of the circuits in term of the output voltage were measured before and after the diodes being irradiated. It was observed, at 4 MGy, the half-wave rectifier output voltage degrades by 6.2 times as compared to before irradiation. Meanwhile, the output voltage of the buck converter degrades by 1.7 times; and for boost converter, the degradation of the output voltage is approximately 4.6 times for 4MGy radiation. These degradations are believed to be due to the increase in the series resistance of the Schottky diodes which is caused by the defects introduced inside the semiconductor during the irradiation and also the increase of turn-on voltage of the diodes after being irradiated

In vitro fermentation of broiler cecal content : the role of oactobacilli and pH value on the composition of microbiota and end products fermentation.

Aim: To assess the probiotic effects of Lactobacillus agilis JCM 1048 and L. sali-varius ssp. salicinius JCM 1230 and the pH on the cecal microflora of chicken and metabolic end products. Methods and Results: An in vitro system, operated with batch bioreactor, was used for this assessment. Selected bacterial species were monitored at two pH values, over 24 h of batch culture incubation. The concentration of short chain fatty acids (SCFA) and lactate in the fermented material was also determined. The addition of L. agilis JCM 1048 and L. salivarius ssp. salicinius JCM 1230 into vessel 2 (Cc + P) increased the total anaerobes, lactobacilli and bifidobacteria after 24 h incubation. Moreover, lactobacilli supplementation decreased the total aerobes and streptococci, but it did not have any effects on coliforms. The supplementation of lactobacilli in vessel 2 (Cc + P) was found to significantly increase the production of lactate, propionate and butyrate. Further- more, pH did not alter the formation of butyrate, whereas the production of acetate and propionate was significantly decreased at pH = 5Æ 8.Conclusions:L. agilis JCM 1048 and L. salivarius ssp. salicinius JCM 1230, as probiotic bacteria, have the ability to re-establish proper microbial balance by the formation of lactate as well as propionate, and stimulate butyrate-producing bacteria to produce butyrate in the chicken cecum. Significance and Impact of the Study: This study was the first to report this under in vitro conditions, highlighting the probiotic roles of the two Lactobacillus strains in broiler cecal fermentation at different initial pH. These useful data can be helpful in improving the fermentation process in chicken cecum

Aerodynamic behavior of a compound wing configuration in ground effect

The aerodynamic coefficients of wing in ground effect can be affected with its design which can be the main parameter for efficiency of wing-in-ground effect craft. In this study, the aerodynamic coefficients of a compound wing were numerically determined in ground effect. The compound wing was divided into three parts with one rectangular wing in the middle and two reverse taper wings with an anhedral angle at the sides. An NACA6409 airfoil was employed as a section of wings. Three dimensional (3D) computational fluid dynamics (CFD) was applied as a numerical scheme. A realizable k-e turbulent model was used for simulation the turbulent flow around the wing surfaces. For validation purpose, the numerical results of a compound wing with aspect ratio 1.25, at ground clearance of 0.15 and different angles of attack were compared with the current experimental data. Then, the aerodynamic coefficients of the compound wings were computed at various ground clearances and angle of attack of 4°. According to pressure and velocity distribution of air around wing surfaces, ground clearance had considerable effects on ram effect pressure and tip vortex of the compound wing, and aerodynamic coefficients of the compound wing had some improvements as compared with the rectangular wing

Static stability of a compound wing configuration in ground effect

The height static stability of a wing can be a main concern for conceptual design of wing-in-ground effect (WIG) crafts. In this research, the stability of a rectangular and compound wing was computationally predicted in ground effect. A realizable k-e turbulent model was used for simulation the flow filed over the wing surfaces. First, the drag coefficient and lift to drag ratio of numerical simulation were validated by experimental data of the rectangular wing. Next, the stability of the compound wing respect to different ground clearances will be determined and compared with rectangular wing. This study illustrated a deep understanding of static stability of present compound wing in ground effect, which eventually can be a guideline for researchers and designers of WIG craft

Physicochemical properties of virgin coconut oil extracted from different processing methods

Virgin Coconut Oils (VCO) were prepared from fresh-dry (grated coconut route), chilling and thawing, enzymatic and fermentation method in this study. All of the VCO produced conformed physicochemically to the standards established by the Asian and Pacific Coconut Community (APCC) and Codex Alimentarius Commission. The highest FA (fatty acid) is lauric acid in all of the VCO and ranged from 46.36-48.42 %, while the principal TAG (triacylglycerol) is LaLaLa (La: Lauric) with 17.94-19.83 % of the total TAG. Tocopherol analysis showed the presence of beta, gamma and delta tocopherols at low levels. In all, the physicochemical, FA and TAG analyses of the VCO extracted from different methods showed some significant differences, while the tocopherol content does not differ significantly among the different types of extraction methods used