Preliminary investigations on an enzyme immobilized optical biosensor for arsenite detection

Arsenite is an inorganic form of arsenic that poses hazardous effect to human. It is a common environmental heavy metal contaminant ubiquitously found in water and groundwater. In this study, an optical biosensor for arsenite determination was developed by immobilization of crude arsenite oxidase (Aio) extracted from recombinant E. coli, in chitosan solution coated on triacetyl-cellulose membrane employing DCPIP as colour indicator. The arsenite oxidase (Aio) was successfully expressed and extracted from recombinant E. coli strain BL21 (DE3). The protein concentration and specific activity of the crude arsenite oxidase were determined. Expression of Aio was confirmed by SDS-PAGE. The crude Aio was also successfully immobilized in chitosan and coated on triacetyl cellulose membrane. The response time and dynamic range of the optical biosensor were optimized. The response time of the developed biosensor was 15 minutes. The amount of DCPIP reduced (ΔA) was inversely proportional to the arsenite concentration. Standard calibration curve for arsenite detection was achieved within the range of arsenite concentration from 25 μM to 200 μM. The maximum detection limit was determined to be 250 μM arsenite

Simulation of fuel economy for Malaysian urban driving

By understanding the implications of real-world driving conditions, improved fuel economy via a strategy of key technologies can be implemented to assist fuel economy validation during development programs. Vehicles in real-world driving conditions regularly travel at idle, low and medium speeds, particularly for urban driving, and this has a crucial weight in overall vehicle fuel economy, given the residencies at the lower engine speed and load region. This paper presents the validation of the derived engine conditions representing Malaysian actual urban driving in an attempt to formulate representative fuel economy data. The measurements were conducted through on-road urban driving within Kuala Lumpur to establish representative driving conditions. The effectiveness of the proposed conditions was then validated in terms of fuel economy using a simulation. The discrepancy between the fuel economy in the proposed conditions and the real-world measurements has improved, falling to 11.9% compared to 43.1% reported by the NEDC

Microstructural evaluation of Bi-Ag and Bi-Sb lead-free high-temperature solder candidates on copper substrate with multiple reflow number

An impetus has been provided towards the development of lead-free solders by worldwide environmental legislation that banned the use of lead in solders due to the lead toxicity. This study focus on Bi-Ag and Bi-Sb solder alloys, in compositions from 1.5 to 5 wt % Ag and Sb. The effects of Ag and Sb amount, and reflow number on the microstructure and morphology of solder bulk were analysed by optical microscope and scanning electron microscope-energy dispersive X-ray. Based on the results, the grain boundary grooving was observed in all samples except Bi-5Sb in all three reflows. Metallurgical and chemical reaction between interface and solders were found in Bi-5Sb solder alloys in different reflow numbers which lead to appearance of Cu3Sb intermetallic compound layer at the interface. Reflow numbers had a significant effect on the size of Cu-rich phase. Also it was observed that, with increasing reflow number Bi-Cu phase found in Bi-2.5Sb solder dissolves into the solder bulk

Interfacial reaction of Bi–Ag and Bi–Sb solders on copper substrate with multiple reflow number

Owing to the toxicity of lead, much effort has been put in studies on lead-free solders after environmental legislations prohibited the use of lead in these parts worldwide. Here, Bi–Ag and Bi–Sb alternative solder alloys containing 1·5–5 wt-% Ag and Sb were investigated. The effect of the reflow number and weight percentage of Ag and Sb on the surface properties of solders and interfacial reactions between the solder bulk and the Cu substrate were analysed by optical microscopy and scanning electron microscopy–energy dispersive X-ray. The results show that by increasing the reflow number and wt-% of Ag and Sb in the solder bulk, the thickness of the mechanical grain boundary grooving is increased. However, the thickness of the Cu3Sb intermetallic compound layer at the interface of Bi–5Sb decreased by increasing the reflow number. Moreover, our findings show that the amount of Ag and Sb in solder alloys and the reflow number have different behaviours on the wettability properties. By increasing the reflow number, the wetting angle decreased in Bi–Ag solder alloys, whereas it increased in Bi–Sb solder alloys

Air Quality Study at Different Elevation Levels Using Drone Payload Air Quality Measurement Device (D-PAQ)

Construction sites can be found in both urban and rural areas, often in close proximity to residences. They can thus cause home pollution due to the distance and the materials used. This study aims to visualize PM2.5, PM10, temperature and humidity by producing air quality mapping and correlating parameters at the stadium and construction site. An Arduino-based air quality measurement payload device was developed to measure the air quality by different levels. The drone was used to collect air quality data by mounting the device to the drone. Measurements were taken at three different elevations for each study area, and the application software generates the air quality map based on the location coordinates. The correlation evaluation of the concentration of PM2.5 and PM10 with temperature and humidity was then determined. The results showed that the concentrations of PM2.5 and PM10 at the construction site are much higher compared to the stadium due to the construction activities nearby. Keywords: air quality, unmanned aerial vehicle, mappin

The study of the effect of intake valve timing on engine using cylinder deactivation technique via simulation

There are many technologies that being developed to increase the efficiency of internal combustion engines as well as reducing their fuel consumption. In this paper, the main area of focus is on cylinder deactivation (CDA) technology. CDA is mostly being applied on multi cylinders engines. CDA has the advantage to improve fuel consumption by reducing pumping losses at part load engine conditions. Here, the application of CDA on 1.6L four cylinders gasoline engine is studied. One-dimensional (1D) engine modeling work is performed to investigate the effect of intake valve strategy on engine performance with CDA. 1D engine model is constructed based on the 1.6L actual engine geometries. The model is simulated at various engine speeds at full load conditions. The simulated results show that the constructed model is well correlated to measured data. This correlated model is then used to investigate the CDA application at part load conditions. Also, the effects on the in-cylinder combustion as well as pumping losses are presented. The study shows that the effect of intake valve strategy is very significant on engine performance. Pumping losses is found to be reduced, thus improve fuel consumption and engine efficiency

AC breakdown behavior of SF6/N2 gas mixtures under non-uniform field electrode configurations

Sulphur hexafluoride (SF6) gas owns remarkable properties as insulation medium and current interrupter, which make it being widely used in gas-insulated equipment up to now. However, SF6 gas has a drawback that gives adverse effect to the environment since it is a strong greenhouse gas. As the effort to minimize the SF6 usage, this study was conducted to investigate the AC breakdown behavior of SF6/N2 gas mixtures with 10/90 ratio at low pressure levels (i.e. 0.11 MPa to 0.15 MPa) under non uniform field (i.e. R0.5-plane and R6-plane electrodes configurations). The results of the study indicate that the breakdown voltage of SF6/N2 gas mixtures in non-uniform field increases linearly with the increase of gas pressure and electrodes gap distance. As a function of gap distance, a higher increasing rate of breakdown voltage values were achieved at lowest pressure of 0.11 MPa compared to other pressure levels. In addition, it is also found that a higher breakdown voltage values was obtained under R6-plane configuration. But, the difference in breakdown voltage values between R0.5-plane and R6-plane configuration is less significant as the gap distance is increased. It is also observed that the field efficiency factor of R6-plane is higher than R0.5-plane which indicates a more uniform field exists between the electrodes

Experimental study to identify common engine part load conditions between Malaysian city driving and NEDC test

This paper describes an experimental study conducted to identify the common engine part load conditions between Malaysian city driving and NEDC (New European Driving Cycle) test on a 4 cylinder gasoline fuelled engine, with multi-point fuel injection system, and continuous variable transmission vehicle. This is to pinpoint a regional area from the part load map in the attempt to strategize key technologies such as CDA (Cylinder Deactivation) or CNG (Compressed Natural Gas). Technologies such as CDA or CNG do not operate at all engine operations. Due to certain drawbacks, the operation of the technologies must be strategized to obtain most benefit from the engine. With the knowledge of the common part load region, these technologies could be integrated and strategized into the region to reduce overall fuel consumption. With improvements in fuel consumption respective to the identified common part load operations, the overall fuel consumption benefit does not only serve the legislation but also most importantly benefit the local consumers who travel on Malaysian roads. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved

Critical Discussion of Ex situ and In situ TEM Measurements on Memristive Devices

Memristors are promising candidates for new memory technologies and are capable to mimic synapses in artificial neural networks. The switching in memristive devices occurs typically in few nanometer thin dielectric layers. The direct observation of the switching mechanism is crucial for better comprehension and improvements of memristors. Therefore, in situ experiments are conducted in a transmission electron microscope (TEM). However, sample preparation processes and electron beam irradiation can lead to a chemical and structural modification of the active layers. Moreover, devices may show significant device-to-device variability due to the details of processing parameters. Thus, it is essential to characterize the identical device electrically before microstructural analysis

Fuzzy Logic Controller Design for Intelligent Air-Conditioning System

Inefficient air cooling systems may cause of wasting energy in a great amount specially in the urban area. Being the most popular cooling system, air-conditioners have been used in domestic usage as well as in industrial applications. However, the unintelligent nature of such cooling system gives rise to excess energy consumption which causes a huge problem in the current energy hungry world. In this paper, we present design of a fuzzy logic controller for the intelligent air-conditioning system. The performance of the controller is also simulated. The proposed controller has the adaptive nature to control fan and compressor speed which leads to reducing power consumption. Also, the system controls the operation mode to retain the healthy oxygen level and humid condition of the indoor environment