The effects of transformational leadership on teacher attitudes and student performance in Singapore

Transformational leadership theory was examined in 89 schools in Singapore using a split sample technique (N = 846 teachers). The study sought to examine the influence of transformational leader behavior by school principals as it related to organizational commitment, organizational citizenship behavior, teacher satisfaction with leader, and student academic performance. Attitudinal and behavioral data were collected from both teachers and principals; student academic performance was collected from school records. School level analyses showed that transformational leadership had significant add-on effects to transactional leadership in the prediction of organizational commitment, organizational citizenship behavior, and teacher satisfaction. Moreover, transformational leadership was found to have indirect effects on student academic achievement. Finally, it was found that transactional leadership had little add-on effect on transformational leadership in predicting outcomes. Implications and directions for future research are discussed.     

Influence of HCl on oxidation of gaseous elemental mercury by dielectric barrier discharge process

The influence of HCl on the oxidation of gaseous elemental mercury (Hg0) has been investigated using a dielectric barrier discharge (DBD) plasma process, where the temperature of the plasma reactor and the composition of gas mixtures of HCl, H2O, NO, and O2 in N2 balance have been varied. We observe that Cl atoms and Cl2 molecules, created by the DBD process, play important roles in the oxidation of Hg0 to HgCl2. The addition of H2O to the gas mixture of HCl in N2 accelerates the oxidation of Hg0, although no appreciable effect of H2O alone on the oxidation of Hg0 has been observed. The increase of the reaction temperature in the presence of HCl results in the reduction of Hg0 oxidation efficiency probably due to the deterioration of the heterogeneous chemical reaction of Hg0 with chlorinated species on the reactor wall. The presence of NO shows an inhibitory effect on the oxidation of Hg0 under DBD of 16% O2 in N2, indicating that NO acts as an O and O3 scavenger. At the composition of Hg0 (280 microg m(-3)), HCl (25 ppm), NO (204 ppm), O2 (16%) and N2 (balance) and temperature 90 degrees C, we obtain the nearly complete oxidation of Hg0 at a specific energy density of 8 J l(-1). These results lead us to suggest that the DBD process can be viable for the treatment of mercury released from coal-fired power plants.     

A sensitive and robust method for the determination of alkylphenol polyethoxylates and their carboxylic acids and their transformation in a trickling filter wastewater treatment plant

This paper presents a method for the determination of alkylphenols, alkylphenol polyethoxylates (APEO) and alkylphenol ethoxycarboxylates (APEC) in the aqueous and particulate phase of wastewater samples. Quantification was achieved by liquid chromatography-tandem mass spectrometry. The sensitivity of the method is demonstrated by low detection limits, in the dissolved phase 1.2-9.6ngl(-1) for alkylphenol, AP(1-3)EO and APEC and 0.1-4.1ngl(-1) for longer chain alkylphenol polyethoxylates. The method detection limit for particulate phase samples ranged from 6 to 60ngg(-1) for AP, AP(1-3)EO and APEC; with the longer chain APEO being from 0.5 to 20ngg(-1). Matrix effects were noted in complex matrix rich samples. There was a distinct change in the distribution of alkylphenol ethoxylates during biological treatment of the wastewater, with the major biotransformation products observed being carboxylated derivatives at concentrations of up to 1768ngl(-1). Shorter chain APEO were present in higher proportions in the suspended solids, due to their higher affinity to particulate matter compared to the long-chain oligomers.     

Protocol for early detection and evaluation of inhibitory wastewater using combined aerobic respirometric and anaerobic batch techniques.

Faced with the task of treating significant volumes of complex industrial wastewaters, the biological components of municipal wastewater treatment plants are operating under the risk of toxic or inhibitory contaminants from the industrial effluents that may be detrimental to their operation. This might lead to undesirable effluent toxicity and/or result in permit violations. Therefore, there is a need for upset early warning systems that can protect full-scale plants from toxic or inhibitory constituents in the incoming wastewaters. This study focused on the development of a protocol for rapid detection of potentially toxic inhibitory or toxic wastewaters using combined aerobic respirometric and anaerobic batch techniques. Aerobic respirometers equipped with automated data acquisition systems were used as potential early warning devices. The inhibition effect on carbon and nitrogen oxidation was assessed. The degree of inhibition was evaluated as the concentration causing 50% reduction in microbial activity, which was estimated by an inhibition model. Anaerobic toxicity assays were also conducted to evaluate the inhibitory effects of the toxic compounds to anaerobic inocula obtained from a master culture reactor fed with ethanol. The developed protocol for early detection of toxicity was validated using wastewater samples from a biotechnology industry and a food processing industry, and pure chemicals such as furfural and phenol. Varying degrees of sensitivity were observed in the study when different groups of microorganisms, wastewater samples, and chemicals were tested. The comparison of aerobic and anaerobic inhibition suggested the importance of using both aerobic and anaerobic cultures to maximize the necessary sensitivity of the protocol.     

Tsunami run-up and inundation along the coast of Sabah and Sarawak,Malaysia due to a potential Brunei submarine mass failure

Submarine landslides, also known as submarine mass failures (SMFs), are major natural marine disasters that could critically damage coastal facilities such as nuclear power plants and oil and gas platforms. It is therefore essential to investigate submarine landslides for potential tsunami hazard assessment. Three-dimensional seismic data from offshore Brunei have revealed a giant seabed mass deposited by a previous SMF. The submarine mass extends over 120 km from the continental slope of the Baram Canyon at 200 m water depth to the deep basin floor of the Northwest Borneo Trough. A suite of in-house two-dimensional depth-averaged tsunami simulation model TUNA (Tsunami-tracking Utilities and Application) is developed to assess the vulnerability of coastal communities in Sabah and Sarawak subject to potential SMF tsunami. The submarine slide is modeled as a rigid body moving along a planar slope with the center of mass motion parallel to the planar slope and subject to external forces due to added mass, gravity, and dissipation. The nonlinear shallow water equations are utilized to simulate tsunami propagation from deepwater up to the shallow offshore areas. A wetting-drying algorithm is used when a tsunami wave reaches the shoreline to compute run up of tsunami along the shoreline. Run-up wave height and inundation maps are provided for seven densely populated locations in Sabah and Sarawak to highlight potential risks at each location, subject to two scenarios of slide slopes: 2° and 4°. The first wave may arrive at Kudat as early as 0.4 h after the SMF, giving local communities little time to evacuate. Over a small area, maximum inundated depths reaching 20.3 m at Kudat, 26.1 m at Kota Kinabalu, and 15.5 m at Miri are projected, while the maximum inundation distance of 4.86 km is expected at Miri due to its low-lying coast. In view of the vulnerability of some locations to the SMF tsunami, it is important to develop and implement community resilience program to reduce the potential damage that could be inflicted by SMF tsunamis.     

Catalytic oxidation for air pollution control

Bench-scale experiments have been conducted to evaluate a series of titania-supported Pt-Pd (as oxides) catalysts in the presence and absence of MoO₃ and Fe₂O₃ additives for their effectiveness in the complete catalytic oxidation of volatile organic compounds (VOCs) in air likely to be found in waste gases. Under oxidizing conditions, all of the catalysts promoted the complete oxidation of VOCs to CO₂ and H₂O. 99 % Conversion was achieved with a C₂H₄-C₂H₆ gas mixture in air at temperatures between about 160–450 °C and at a space velocity of 20,000 h^?1. Oxidation activity for the titania supported catalysts were found to decrease in the order Pt-Pd-Mo-Fe > Pt-Pd-Mo > Pt-Pd-Fe > Pt-Pd. However, the addition of MoO₃ and Fe₂O₃ increase the catalyst activity and reduce the reaction temperature for the complete destruction. Ageing was also performed in order to study the stability of the most active catalyst. Pt-Pd-Mo-Fe (as oxides) on titania catalyst is effective in oxidizing a wide range of volatile organic compounds at relatively low temperatures (220–405 °C) and and at a space velocity of 40,000 h^?1 and is resistant to poisoning by halogenated and amine volatile organic compounds.     

Ecology of marine fouling organisms at Eastern Johore Strait

Marine biofouling causes problems to marine structure and obstructs condenser tubes in cooling systems which use sea water as the coolant. The main purpose of this study is to investigate the seasonal ecology of biofouling organisms such as the green mussel, Perna viridis, the dominant fouling species in the Eastern Johore Straits at the Senoko Power Station. The spawning time and its relationship with environmental conditions were studied. The physical, chemical and biological conditions of the sea at Senoko were monitored for a year. Settling slides were used to study the fouling succession in different monsoon seasons. The study showed that there were two main spawning peaks for the green mussel and that these peaks occurred during the intermonsoon months of November and April. These peaks were also correlated with the bimodal patterns for salinity, dissolved oxyen, bivalve veliger larval density and total plankton biomass of the Eastern Johore Strait water. Succession patterns were similar during the two monsoon seasons, however, the rate of fouling was probably greater during the southwest monsoon months. It is therefore advisable that the control or reduction of biofouling in Eastern Johore Strait should take into account the seasonal fluctuations and spawning of the fouling organisms.     

Factors affecting the leaching of lead from UPVC pipes

This paper summarizes the results of a series of studies on the various factors that affect the leaching of lead from unplasticized poly(vinyl chloride) (UPVC) pipes. Factors that were studied include temperature, pH and extractants. Results showed that, for a given UPVC pipe, the rate of leaching of lead depended primarily on temperature and the nature of extractants. While the rate of leaching of lead was quite low with distilled water, it was very much enhanced by the presence of low concentration of anions such as Cl^-, HPO _inf4 ^sup2- HCO _inf3 ^sup- , NO _inf3 ^sup- , SO _inf4 ^sup2- and EDTA. EDTA, being a strong complexing agent, was most effective. Rates of leaching were found to be higher at elevated temperature except in the cases of HPO _inf4 ^sup2- and EDTA. Effect of pH was not pronounced. The temperature at which the UPVC pipes were extruded was found to affect the rate of leaching of lead. Pipes extruded at 190°C were found to have lower rate of leaching than those extruded at 180°C and 170°C. Analysis of the pipes by Scanning Electron Microscopy showed that the distribution of lead in the pipes extruded at 190°C was more uniform than those extruded at 170°C.     

Poly(sodium acrylamidoalkanoates) in water treatment

Poly(sodium 6-acrylamidocaproate), poly(sodium 11-acrylamidoundecanoate), poly(sodium 11-N-methylacrylamidoundecanoate) and poly(sodium 11-N-ethylacrylamidoundecanoate) have been synthesized. The performance of these anionic polyelectrolytes as coagulant aids in water treatment was assessed by the jar test. The effects of polymer dosage and pH on their performances were investigated in order to establish the optimum flocculation conditions. The effectiveness of these polyelectrolytes as well as a commercially available cationic polyamine organic coagulant aid was compared in terms of floc size, settling rate and the quality of treated water. Poly(sodium 6-acrylamidocaproate) and poly(sodium 11-acrylamidoundecanoate) were superior to poly(sodium 11-N-methylacrylamidoundecanoate) and poly(sodium 11-N-ethylacrylamidoundecanoate), and they are as effective as the commercial cationic coagulant aid.     

Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) and 2,3,7,8-TCDD equivalents (TEQs) in sediment from the Hyeongsan River, Korea

Sediment, pore water and water samples from the Hyeongsan River, Korea were analyzed for several classes of halogenated aromatic hydrocarbons (HAHs) and their dioxin-like activities were evaluated using the in vitro H4IIE-luc bioassay. Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) were detected in sediments from all six sampling locations with mean concentrations of 2.8 x 10(2) pg/g, 190 pg/g, and 61.4 ng/g, dw, respectively. Polycyclic aromatic hydrocarbons (PAHs) were predominated by 4-6 ring compounds with concentrations in the range of 5.30-7680 ng/g, dw. Chemical profiles of target analytes in sediment and water samples revealed that there was a gradient of concentrations along the river from upstream to downstream, which suggested that the primary source was a wastewater reservoir adjacent to a sewage treatment plant (STP). TEQs derived by summing the product of concentrations of individual congeners by their respective relative potencies (REPs or TEFs) ranged from 4.3 x 10(-1) to 1.1 x 10(3) pg/g, dw. Raw Soxhlet extracts from all six sampling locations induced significant dioxin-like responses in the H4IIE-luc bioassay. TCDD-EQs derived from H4IIE bioassay ranged from 7 x 10(-3) to 1.5 x 10(3) pg/g, dw, which were significantly correlated with TEQs (r2 = 0.994, p < 0.05). Among the three Florisil fractions tested, PCDD/Fs in fraction (F2) induced the greatest magnitude of response (range: 24-83%-TCDD-max.) in the H4IIE-luc assay. Comparison of the TEQ and TCDD-EQ suggested little non-additive interaction between fractions and AhR-active and inactive compounds. Concentrations of individual congeners as well as TEQs and TCDD-EQs suggest inputs from the industrial center waste stream in the Hyeongsan River.