Health risk assessment due to emissions from medical waste incinerator in Malaysia

In this research, health risk assessment due to the emission of pollutants from a medical waste incinerator located within industrial estate in the northern part of Malaysia was presented. The influence of pollutants emission in the vicinity of the incineration plant was the main concern in this research. The measured emissions of pollutants from the stacks of the studied plant that may pose risk to human health and the environment are compared against the acceptable limit as in the Environmental Quality (Clean Air) Regulation 2014. Next, the levels of pollutants in ambient air are assessed in comparison with the guideline established by the Malaysia Ambient Air Quality Guideline (MAAQG). The health risk assessment was then conducted by calculating the quantitative risk for non-carcinogenic and carcinogenic pollutants. The study reveals that the total cancer risk due to emission of carcinogenic pollutants from the incinerator is 1.84 × 10-5, which indicates risky circumstances as the calculated risk is higher than the benchmark of acceptable risk of 1 × 10-6. Meanwhile the health risk calculated due to emission of non-carcinogenic pollutants ranges between 0.000286 and 0.1, indicating acceptable risk. The result shows that the non-carcinogenic pollutants emitted from the studied medical waste incinerator are within the acceptable exposure limits. However, for carcinogens, the released amounts may cause human health risk, and therefore demands for further attention to reduce the concentrations as low as reasonably practicable, at least in compliance with the established guidelines

NUMERICAL EXPERIMENT ON EFFECT OF SURFACE ROUGHNESS FOR HEAT AND FLOW AROUND TWO CONTACTING PARTICLES

The aim of the present work is to establish a model of heat transfer between particles by using the numerical simulation that can be incorporated in the discrete element method (DEM). The contact heat transfer between particles can be regarded as a contact thermal resistance problem. In the thermal resistance model, the local characteristics, e.g. exact contact area and heat flux distribution on particle surface, are important. However, it is difficult to measure such factors in detail. Accordingly, the authors utilized a numerical simulation. The thermal resistance was modeled by placing a small solid block between the contacting areas in the simulation. The small solid thickness represents the surface roughness and the width represents the contact force. The simulated temperature profile along the center line through two particle’s centers well agreed with measured one

Distributed Cooperative Spectrum Sensing in Cognitive Radio Networks with Adaptive Detection Threshold

This paper proposes a cooperative sensing algorithm based on distributedfusion strategy and maintained probability of false alarm for cognitive radio. It furtherintroduces a reporting strategy that discusses how cooperative sensing in distributedmanner can select among possible candidates in order to reduce bandwidthrequirement. We adopted a dynamic distributed architecture for cooperative sensingbased on the link quality and found condition on the channel quality for cooperation tobe beneficial. Using probability of detection, and BER metrics we evaluated theperformance improvement of distributed cooperation over direct cooperation and noncooperativesensing. We used analytical formulation with possible candidate selectioncriteria to investigate and maximize the cooperation gain. By employing suchdistribution and selection technique, the reporting error due to the fading channel isreduced. Results show that the method effectively improve performance of sensing, itincrease the probability of detection up to 0.9 at <0.1 probability of false alarm.Sensitivity requirement is reduced with network scale and the number of nodesparticipate in decision fusion is reduced about 42% at probability of false alarm 0.1.ROC curve has obvious improvement compared with existing methods

Impaired OXPHOS Complex III in Breast Cancer

We measured the mitochondrial oxidative phosphorylation (mtOXPHOS) activities of all five complexes and determined the activity and gene expression in detail of the Complex III subunits in human breast cancer cell lines and primary tumors. Our analysis revealed dramatic differences in activity of complex III between normal and aggressive metastatic breast cancer cell lines. Determination of Complex III subunit gene expression identified over expression and co-regulation of UQCRFS1 (encoding RISP protein) and UQCRH (encoding Hinge protein) in 6 out of 9 human breast tumors. Analyses of UQCRFS1/RISP expression in additional matched normal and breast tumors demonstrated an over expression in 14 out of 40 (35%) breast tumors. UQCRFS1/RISP knockdown in breast tumor cell line led to decreased mitochondrial membrane potential as well as a decrease in matrigel invasion. Furthermore, reduced matrigel invasion was mediated by reduced ROS levels coinciding with decreased expression of NADPH oxidase 2, 3, 4 and 5 involved in ROS production. These studies provide direct evidence for contribution of impaired mtOXPHOS Complex III to breast tumorigenesis

A new technique to improve the machinability of hardened steel AISI H13 in end milling

Hardened materials like AISI H13 steel are generally regarded as difficult to cut materials because of their high hardness due to high carbon content, which however allows them to be used extensively as the hot working tools like, dies and moulds. The challenges in machining this steel in hardened state led to many research works dedicated towards enhancing its machinability. In this work, preheating technique has been used to improve machinability of the material under different cutting conditions..

Using chemometrics in assessing langat river water quality and designing a cost-effective water sampling strategy.

Seasonally dependent water quality data of Langat River was investigated during the period of December 2001 – May 2002, when twenty-four monthly samples were collected from four different plots containing up to 17 stations. For each sample, sixteen physico-chemical parameters were measured in situ. Multivariate treatments using cluster analysis, principal component analysis and factorial design were employed, in which the data were characterised as a function of season and sampling site, thus enabling significant discriminating factors to be discovered. Cluster analysis study based on data which were characterised as a function of sampling sites showed that at a chord distance of 75.25 two clusters are formed. Cluster I consists of 6 samples while Cluster II consists of 18 samples. The sampling plots from which these samples were taken are readily identified and the two clusters are discussed in terms of data variability. In addition, varimax rotations of principal components, which result in varimax factors, were used in interpreting the sources of pollution within the area. The work demonstrates the importance of historical data, if they are available, in planning sampling strategies to achieve desired research objectives, as well as to highlight the possibility of determining the optimum number of sampling stations which in turn would reduce cost and time of sampling

Enhancement of machinability of nickel based alloy - inconel 718 by induction preheating in end milling using ceramic inserts

Unique combinations of high strength properties maintained at elevated temperature and high resistance to chemical degradation have made Nickel based alloy, Inconel 718 suitable for application as aerospace components. However, the same properties are responsible for very poor machinability of the material, as Inconel is one of the most difficult to cut materials. The main reason for poor machinability is generation of high heat during machining which lead to premature failure of the tool due to plastic deformation and diffusion. Uncoated and coated tools have been found to be not efficient in cutting this materials and the application of preheated resulted in not significant improvement in their machinability. PCD tools are not recommended for machining this material since it contains iron which acts as a catalyst to convert diamond into graphite at temperatures in excess of 700 0C. PCBN tools are very costly and also did not show very good performance in machining Inconel 718. Ceramic tools have proved to have performed well in machining the material. However, there was so far no work performed performance of ceramic tools in machining Inconel 718 using preheated technique. Since ceramic tools can perform under high temperatures, it was expected that preheated machining using ceramic tools would desired results. In this research work induction heating technique in combination of the application of ceramic tools was adopted as one of the machining techniques in order to improve the machinability of the material. The effect of preheated machining of Inconel 718 has been analyzed in terms of tool wear, surface roughness and chip formation. The advantages of preheated machining are demonstrated by appreciable increase in tool life, better surface roughness values and improved chip formation compared to room temperature machining

Synthesis and electrochemical characterizations of poly(3,4-ethylenedioxythiophene/manganese oxide coated on porous carbon nanofibers as a potential anode for lithium-ion batteries

Poly(3,4-ethylenedioxythiophene)/manganese oxide coated on porous carbon nanofibers (P-CNFs/PEDOT/MnO2) is developed as an advanced anode material via the innovative combination of multiple routes, such as electrospinning, carbonization and electrodeposition. The structural and morphological characterization of the P-CNFs/PEDOT/MnO2 electrode indicates that crosslinked and rough surface provides, as a strategic point, enough active sites for Li+ storage. PEDOT nanoparticles and irregular block shape of MnO2 are randomly oriented on the P-CNFs surface, thus allowing a possible electron-conducting pathway, increment in catalytic activity as well as a buffer of the volumetric changes upon cycling. Consequently, the obtained P-CNFs/PEDOT/MnO2 electrode exhibits a truly promising electrochemical performance, which displays discharge capacity of 1477 mAh/g, better than that of P-CNFs/PEDOT (1191 mAh/g), P-CNFs/MnO2 (763 mAh/g) and P-CNFs (433 mAh/g), at a current density of 2 mA/g. In addition, satisfactory electrochemical performances of the as-prepared P-CNFs/PEDOT/MnO2 electrode after 20 cycles of charge/discharge are detected, with a Coulombic efficiency higher than 90% and a charge-transfer resistance being relatively smaller (131.91 ohm) than that of P-CNFs/PEDOT (232.66 ohm) and P-CNFs/MnO2 (169.17 ohm) electrodes. Thus, these results indicate that the P-CNFs/PEDOT/MnO2 electrode could offer a great potential to replace commercial graphite for lithium-ion batteries

Machinability aspects in heat assisted machining of hardened steel AISI H13 using coated carbide tool

AISI H13 tool steel is one of the major hardened materials used extensively for making hot working moulds and dies, because of favourable combination of their mechanical and thermal properties. However, these enhanced properties, especially high hardness make them very difficult to machine using conventional techniques. In the current project a technique of workpiece heat assisted machining was adopted as a possible means of improving machinability of the material. Machining was conducted on a vertical machining centre using TiAlN coated carbide inserts and heating of the workpiece was carried out using an induction heater. An online vibration monitoring system was used to record the vibration signals during machining. Comparison between room temperature and heat assisted machining was then made in terms of tool wear and life, surface finish and chatter/vibration. It was found that tool life was higher under heat assisted machining condition. Heat assisted machining also yielded lower surface roughness and lower amplitudes of chatter during machining. AISI H13 tool steel is a widely used material in mould and die making industry, because of its high hardness and ability to sustain severe operating condition. The other properties that make H13, as an inevitable material for mould and die are high resistance to deformation and breaking under high loads, high hardness at elevated temperature and high wear resistant. However, these properties of H13 do possess some of unfavourable effect in terms of machining process. For this, enhancement of machinability of H13 tool steel drew the attention of many researchers and metal cutting scientist. Despite the importance of end milling operation for the manufacturing of mould and die, most of the research work concentrated mainly on the turning operation of H13 tool. In this perspective, the current study adopted preheating as a technique to enhance machinability of H13. The industrial adoption of hard machining was made during the last decade with the improvement of cutting tool material, coating technologies and advanced machining techniques. Generally, hard machining involves the machining of material with a hardness value over 45 HRC. Hard machining has provides a significant cost or lead-time reduction in comparison to traditional route processes. Moreover, adoption of hard machining technique has been the requirement for further improved dimension tolerances in cutting operation. In addition to this, hard machining provides the elimination of distortion due to heat treatment from the process of traditional route processes. Zaima, Shigeo. Takeda, Hirohisa. Morishita, Sadamu (1974) reported a number of advantages of hot machining of cast high silicon aluminum alloys. It can produce comparable surface finish as in abrasive super finishing up to 0.4 μm in average roughness value (CR. Liu and S. Mittal, 1995). This innovative process not only has great potential to save significant cost, to increase production flexibility, and to reduce the pollution due to dry cutting, but also yields parts with higher surface quality and longer service life (CR. Liu and S. Mittal, 1996). Akira et al (2005) compared the performance of CBN and TiAlN coated carbide-cutting tools in milling hardened carbon steel and recommended the TiAlN coated carbide tool for low-speed hard milling. It was also observed that the hardness of workpiece had a great influence on the cutting temperature. In this context, the main objective of this work was to make a comparison on the effectiveness in machining hardened steel AISI H13 under room temperature and preheated condition in terms of tool life, surface finish and vibration and chatter amplitude