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BIO-ADSORPTION OF HEAVY METAL ION FROM WATER USING ACTIVATED CARBON

The discharge of effluent polluted with heavy metals have become a growing concern for researchers around the world. This study evaluated the removal efficiency of commercial activated carbon and rice husk activated carbon as adsorbents for the removal of copper ion in water. A nominal size of 1 mm was obtained after sieving the Rice Husk, washed with distilled water, dried in an oven t at 80 ℃ for 12 hours, and pyrolyzed in a furnace at 550 ℃ for 30 minutes. The chars produced were later air-dried and then activated with lemon juice. The Rice Husk Activated Carbon (RHAC) and Commercial Activated Carbon (CAC) purchased from the market were both subjected to the following analyses: bulk density, X-ray Fluorescence (XRF), Brunauer–Emmett–Teller (BET), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) in order to characterise the adsorbents and to understand their suitability for the removal of copper ion in water. One of the properties of an adsorbent is large pores which is exhibited by the activated carbons as revealed by the SEM analysis. Likewise, the XRF and EDX analyses confirmed that the adsorbents had larger proportion of Silica (50.1 – 50.25%), Carbon (60.06 – 84.87 wt .%) and Oxygen (15.13 – 21.60 wt. %) which is a property of a good adsorbent. BET analysis showed that the surface areas of the rice husk activated carbon and the commercial activated carbon were 998.35 and 1208.25 m2/g, respectively. The bulk densities of the rice husk activated carbon and the commercial activated carbon were 0.3325 and 0.2812 g/cm3, respectively. The maximum removal efficiency using RHAC was observed at 60 ℃ and 120 minutes at 83.96 and 89.21 %, respectively while for CAC the maximum removal efficiency was observed at 60 ℃ at 84.61 % and 30 minutes at 83.3 %. Initial concentration of 20 mg/l was observed to have the highest removal efficiency for the two activated carbon specimens. The modelled effect of initial concentration, temperature and contact time on removal efficiency yielded R2 values of 1, 0.918; 1,1 and 1,1 respectively for the CAC and RHAC.

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MODELLING THE FACTORS AFFECTING CRASH OCCURRENCE AND FREQUENCY RESULTED FROM MOBILE PHONE USE WHILE DRIVING: EVIDENCE FROM AL-NAJAF, IRAQ

The recent reports of road traffic accident statistics in Iraq have disclosed a rise in the number of crash injuries resulted from the use of mobile phone while driving. This paper aims to explore the factors contributing to the occurrence and prevalence of such crashes and near crashes in Al-Najaf governorate, Iraq. A representative sample of 417 drivers were interviewed as part of a questionnaire driving survey. Several frequency and modelling analyses were conducted using the IBM SPSS software. The frequency analysis revealed a high use of mobile phones for calling and texting activities while driving. Almost 20% and 55% of the interviewed drivers reported their involvement in a crash or in a near crash because of such use, respectively. Regarding the developed logistic models, the crash involvement sequential regression analysis revealed that factors such gender, education, handheld phoning, calling-answering frequency, and inadequate driving can affect the likelihood of crash occurrence. In contrast, the ordinal logistic near miss models revealed that age, gender, high phone use rate, and improper driving due to such use are influential factors in rising the likelihood of being in multiple near crashes. The analysis results confirm the influence of using phones in distracting the attention of drivers and hence threating their lives; as a result, these findings would be enlightening for agencies and policy makers interested in highway safety.

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DEVELOPMENT OF MICROSTRUCTURE, MECHANICAL AND WEAR CHARACTERISTICS OF THE BRASS ALLOY PROCESSED BY ECAP

In the present study, the microstructure, mechanical and wear characteristics of commercial Cu-30Zn brass alloy were developed by an equal channel-angular process (ECAP) using a particular die in constant dimensions. The ECAP process was experimentally conducted at room temperature using (1-4) passes in route C with lubricating conditions. Also, the post-annealing treatment at 350 oC has been done for some brass samples, which were deformed with four passes. Findings revealed that by conducting the ECAP, a significant reduction in the grain size of the deformed brass samples is achieved compared to the as-received alloy. The grain refinement increased with the increasing number of ECAP passes. However, the post-annealing treatment increased the grain size of the deformed brass alloy, but still it was lower than the as-received alloy. Moreover, the mechanical performance, i.e. micro-hardness and strength, was significantly enhanced after the ECAP. The samples processed with three passes presented the highest hardness value (237 HV) and mechanical strength (UTS= 692 MPa, and YS= 542 MPa) due to the homogeneous strain hardening and substantial grain refinement throughout the ECAP process. However, the micro-hardness and mechanical strength of brass alloy decreased after post-annealing treatment compared to those of the ECAP deformed samples. The elongation to failure also decreased greatly with increasing the number of passes of ECAP. Additionally, the wear resistance of the investigated samples increased significantly after increasing the number of ECAP passes compared to the as-received alloy. The highest wear resistance has been achieved for samples deformed by three and four passes of ECAP due to the considerable grain size refinement and higher hardness. However, a slight increase in the wear rate occurred after post-annealing treatment on a brass alloy sample processed with four passes due to the increase in grain size.

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GRAPHITE FOAM STRUCTURES AS AN EFFECTIVE MEANS TO COOL HIGH-PERFORMANCE ELECTRONICS

Due to their unique heat transfer features, graphite foams are used in the current analysis to form heat sinks effective enough to dissipate extreme heat generated within high-performance electronics. The heat sinks proposed are formed from foamed-baffles arranged either in parallel or perpendicular to the coolant paths through the staggered slots in between to alleviate the penalty of pressure drop while maintaining high heat dissipation capability. Two different sorts of dielectric coolants namely, air and the FC-3283 electronic liquid developed by 3MTM, have been utilized to directly dissipate the heat generated. The feasibility of the currently proposed heat sinks has been examined numerically based on the volume averaging concept of porous media employing the local thermal non-equilibrium model to account for interstitial heat exchange between the foam solid matrix and the fluid particles flowing across. A wide range of design parameters has been tested including the heat sink configuration along with structural characteristics of the graphite foam used. It has been found that foam baffles oriented perpendicular to the path of coolant flow can dissipate heat by about 50% better than those parallel to it, but with higher pressure losses. It has also been found that heat dissipation capability, for a certain orientation of baffles, can be improved by up to 100% when the foam pore size is doubled with outstanding saving in pressure losses by up to 300%. The impact of operating conditions, including the coolant flowrate and the heat flux applied, has also been inspected. The currently proposed heat sinks have been found efficient to meet the thermal demands of high-performance electronics and sweep away the extreme heat generated there with reasonable cost of pressure drop, where the proper selection of design parameters in light of the operating conditions applied can prevent the emergence of hot spots entirely. Extreme operating conditions, i.e. with heat density of up to 10W/cm2 for air-cooled heat sinks and 100W/cm2 for those cooled with FC-3283, can be well managed when a heat sink is configured from baffles that are oriented perpendicularly to the coolant flow path and formed of graphite foam having low porosity (∅=0.8) and larger pore size

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