Search results for: gas metal arc welding (GMAW)

Authors: Zhang Hui, Wu Caiqiu, Yuan Xuyin, Qiu Jie, Zhang Hanpei

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The heavy metal contaminations were determined with a detailed soil survey in roadside soils along Shenyang-Dalian Highway of Liaoning Province (China) and Pb, Cu, Cd, Ni and Zn were analyzed using the atomic absorption spectrophotometric method. The average concentration of Pb, Cu, Cd, Ni and Zn in roadside soils was determined to be 43.8, 26.5, 0.119, 32.1, 71.3 mg/kg respectively, and all of the heavy metal contents were higher than the background values. Different heavy metal distribution regularity was found in different land use type of roadside soil, there was an obvious peak of heavy concentration at 25m from road edge in the farmland, while in the forest and orchard soil, all heavy metals gradually decreased with the increase of distance from road edge and conformed to the exponential model. Furthermore, the heavy metal contents of heavy metals except Cd were markedly increased compared with those in 1999 and 2007, and the heavy metals concentrations of Shenyang- Dalian Highway were considered medium or low in comparison with those in other cities around the world. The assessment of heavy metal contamination of roadside soils illustrated a common low pollution for all heavy metal and recommended that more attention should be paid to Pb contamination in roadside soils in Shenyang-Dalian Highway.

Keywords: heavy metal contamination, roadside, highway, Nemerow Pollution Index

Procedia PDF Downloads 266

Authors: Sandya Mummullage, Prasanna Egodawatta, Ashantha Goonetilleke, Godwin A. Ayoko

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Urban road dust comprises of a range of potentially toxic metal elements and plays a critical role in degrading urban receiving water quality. Hence, assessing the metal composition and concentration in urban road dust is a high priority. This study investigated the variability of metal composition and concentrations in road dust in four different urban land uses in Gold Coast, Australia. Samples from 16 road sites were collected and tested for selected 12 metal species. The data set was analyzed using both univariate and multivariate techniques. Outcomes of the data analysis revealed that the metal concentrations inroad dust differs considerably within and between different land uses. Iron, aluminum, magnesium and zinc are the most abundant in urban land uses. It was also noted that metal species such as titanium, nickel, copper, and zinc have the highest concentrations in industrial land use. The study outcomes revealed that soil and traffic related sources as key sources of metals deposited on road surfaces.

Keywords: metals build-up, pollutant accumulation, stormwater quality, urban road dust

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Authors: Jisong Ryu, Woosik Lee, Yonggu Jang

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The paper discusses the process of establishing a reliable test bed for verifying the usability of Ground Penetrating Radar (GPR) exploration equipment based on an integrated underground spatial map in Korea. The aim of this study is to construct a test bed consisting of metal and non-metal pipelines to verify the performance of GPR equipment and improve the accuracy of the underground spatial integrated map. The study involved the design and construction of a test bed for metal and non-metal pipe detecting tests. The test bed was built in the SOC Demonstration Research Center (Yeoncheon) of the Korea Institute of Civil Engineering and Building Technology, burying metal and non-metal pipelines up to a depth of 5m. The test bed was designed in both vehicle-type and cart-type GPR-mounted equipment. The study collected data through the construction of the test bed and conducting metal and non-metal pipe detecting tests. The study analyzed the reliability of GPR detecting results by comparing them with the basic drawings, such as the underground space integrated map. The study contributes to the improvement of GPR equipment performance evaluation and the accuracy of the underground spatial integrated map, which is essential for urban planning and construction. The study addressed the question of how to verify the usability of GPR exploration equipment based on an integrated underground spatial map and improve its performance. The study found that the test bed is reliable for verifying the performance of GPR exploration equipment and accurately detecting metal and non-metal pipelines using an integrated underground spatial map. The study concludes that the establishment of a test bed for verifying the usability of GPR exploration equipment based on an integrated underground spatial map is essential. The proposed Korean-style test bed can be used for the evaluation of GPR equipment performance and support the construction of a national non-metal pipeline exploration equipment performance evaluation center in Korea.

Keywords: Korea-style GPR testbed, GPR, metal pipe detecting, non-metal pipe detecting

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Authors: Ritu Chaturvedi, Manoj Paul

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A pot experiment was conducted to investigate the effect of Arbuscular mycorrhizal fungus (AMF) on metal(loid) uptake and accumulation efficiency of Pisum sativum along with physiological and biochemical response. Plants were grown in soil spiked with 50 and 100 mg kg-1 Pb, 25 and 50 mg kg-1 Cd, 50 and 100 mg kg-1 As and a combination of all three metal(loid)s. A parallel set was maintained and inoculated with arbuscular mycorrhizal fungus for comparison. After 60 days, plants were harvested and analysed for metal(loid) content. A steady increase in metal(loid) accumulation was observed on increment of metal(loid) dose and also on AMF inoculation. Plant height, biomass, chlorophyll, carotenoid and carbohydrate content reduced upon metal(loid) exposure. Increase in enzymatic (CAT, SOD and APX) and nonenzymatic (Proline) defence proteins was observed on metal(loid) exposure. AMF inoculation leads to an increase in plant height, biomass, chlorophyll, carotenoids, carbohydrate and enzymatic defence proteins (p≤0.001) under study; whereas proline content was reduced. Considering the accumulation efficiency and adaptive response of plants and alleviation of stress by AMF, this symbiosis can be applied for on-site remediation of Pb and Cd contaminated soil.

Keywords: heavy metal, mycorrhiza, pea, phyroremediation

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Authors: Lin Dong-Yih, Yang S. M., Huang B. W., Lian J. A.

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Super duplex stainless steel has excellent mechanical properties and corrosion resistance. It becomes important structural material as its application has been extended to the fields such as renewable energy and the chemical industry because of its excellent properties. As examples are offshore wind power, solar cell machinery, and pipes in the chemical industry. The mechanical properties and corrosion resistance of super duplex stainless steel can be eliminated by welding due to the precipitation of the hard and brittle σ phase, which is rich of chromium, and molybdenum elements. This paper studies the influence of carbon element on the phase transformation of -ferrite and σ phase in 2507 super duplex stainless steel. The 2507 will be under argon gas protection welded with 316 and 316L extra low carbon stainless steel separately. The microstructural phases of stainless steels before and after welding, in fusion, heat affected zones, and base material will be studied via X-ray, OM, SEM, EPMA i.e. their quantity, size, distribution, and morphology. The influences of diffusion by carbon element will be compared according to the microstructures, hardness, and corrosion tests.

Keywords: complex stainless steel, welding, phase formation, carbon element, sigma phase, delta ferrite

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Authors: Hannachi Med Tahar, H. Djebaili, B. Daheche

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In this approach, we have tried to describe the flattening of welded tubes, and its experimental application. The test is carried out at the (National product processing company dishes and tubes production). Usually, the final products (tubes) undergo a series of non-destructive inspection online and offline welding, and obviously destructive mechanical testing (bending, flattening, flaring, etc.). For this and for the purpose of implementing the flattening test, which applies to the processing of round tubes in other forms, it took four sections of welded tubes draft (before stretching hot) and welded tubes finished (after drawing hot and annealing), it was also noted the report 'health' flattened tubes must not show or crack or tear. The test is considered poor if it reveals a lack of ductility of the metal.

Keywords: flattening, destructive testing, tube drafts, finished tube, Castem 2001

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Authors: Sunthorn Sittisakuljaroen

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The edge waviness in hot rolled steel is a common defect. Variables that effect for such defect include as raw material and machine. These variables are necessary to consider. This research studied the defect of edge waviness for SS 400 of metal sheet manufacture. Defect of metal sheets divided into two groups. The specimens were investigated on chemical composition and mechanical properties to find the difference. The results of investigate showed that not different to a standard significantly. Therefore the roll milled machine for sample need to adjustable rollers for press on metal sheet which was more appropriate to adjustable at both ends.

Keywords: edge waviness, hot rolling steel, metal sheet defect, SS 400, roll leveller

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Authors: Hadda Krarcha, S. Messaasdi

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In order to investigate Hafnium transition metal alloys HfM (M= Co, Ir, Os,Pt, Rh, Ru) phase diagrams in the region of 50/50% atomic ratio, we performed ab initio Full-Potential Linearized Augmented Plane Waves calculations of the enthalpies of formation of HfM compounds at B2 (CsCl) structure type. The obtained enthalpies of formation are discussed and compared to some of the existing models and available experimental data.

Keywords: enthalpy of formation, transition metal, binarry compunds, hafnium

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Authors: Sneha Samal, Iva Petrikova, Bohdana Marvalova

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Influence of grain size, shape and grain boundary diffusion at high temperature oxidation of pure metal is investigated as the function of microstructure evolution in this article. The oxidized scale depends on the geometrical parameter of the metal-scale system and grain shape, size, diffusion through boundary layers and influence of the contamination. The creation of the inner layer and the morphological structure develops from the internal stress generated during the growth of the scale. The oxidation rate depends on the cation and anion mobile transport of the metal in the inward and outward direction of the diffusion layer. Oxidation rate decreases with decreasing the grain size of the pure metal, whereas zinc deviates from this principle. A strong correlation between the surface roughness evolution, grain size, crystalline properties and oxidation mechanism of the oxidized metal was established.

Keywords: high temperature oxidation, pure metals, grain size, shape and grain boundary

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Authors: Shannen Lorraine, Paul Maragh, Tara Dasgupta, Kamaluddin Abdur-Rashid

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(R)-(4,4',6,6'-tetramethoxybiphenyl-2,2'-diyl)bis(diphenylphosphine) (R-Ph-Garphos), and (S)-(4,4',6,6'-tetramethoxybiphenyl-2,2'-diyl)bis(diphenylphosphine) (S-Ph-Garphos) are novel, nucleophilic, chiral atropisomeric ligands. The research explored the synthesis of chiral transition metal complexes containing these ligands and their applications in various asymmetric catalytic transformations. Herein, the transition metal complexes having ruthenium(II), rhodium(I) and iridium(I) metal centres will be discussed. These are air stable complexes and were characterized by CHN analysis, 1H, 13C, and 31P NMR spectroscopy, and polarimetry. Currently, there is an emphasis on 'greener' catalysts and the need for 'green' solvents in asymmetric catalysis. As such, the Ph-Garphos ligands were demethylated thereby introducing hydroxyl moieties unto the ligand scaffold. The facile tunability of the biaryl diphosphines led to the preparation of the (R)-(4,4',6,6'-tetrahydroxybiphenyl-2,2'-diyl)bis(diphenylphosphine) (R-Ph-Garphos-OH), and (S)-(4,4',6,6'-tetrahydroxybiphenyl-2,2'-diyl)bis(diphenylphosphine) (S-Ph-Garphos-OH) ligands. These were successfully characterized by CHN analysis, 1H, 13C, and 31P NMR spectroscopy, and polarimetry. The use of the Ph-Garphos and Ph-Garphos-OH ligands and their transition metal complexes in asymmetric hydrogenations will be reported. Additionally, the scope of the research will highlight the applicability of the Ph-Garphos-OH ligand and its transitional metal complexes as 'green' catalysts.

Keywords: catalysis, asymmetric hydrogenation, diphosphine transition metal complexes, Ph-Garphos ligands

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Authors: Maha A. Younus, Dhefaf H. Badri, Maha A. Al Abayaji, Taha M. Salih

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Polymer metal complexes of poly vinyl alcohol and Cu (II), Ni (II), Mn (II) and Co (III) were prepared from the reaction of PVA with three different percentages of urea. The compound was characterized by fourier transform infrared spectrometry (FTIR) analysis and differential scanning calorimetric (DSC) Analysis. It has been established that the polymer and its metal complexes showed good activities against nine pathogenic bacteria (Escherichia coli, Klebsiellapneumonae, Staphylococcusaureus, Staphylococcus Albus, Salmonella Typhoid, Pseudomonas Aeruginosa, Shigella Dysentery, Proteus Morgani, Brucella Militensis). The polymer metal complexes show activity higher than that of the free polymer. The increasing activities were in the order (polymer < pol-Mn< pol-Co < pol-Ni ˂ pol-Cu). The ability of these compounds to show antimicrobial properties suggests that they can be further evaluated for medicinal and/or environmental applications.

Keywords: antimicrobial activity, PVA, polymer-metal complex, urea

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Authors: Chinnawat Satsananan

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This research aimed to find amount of heavy metal in herb used in Dusit community and compare of heavy metal in each part by quantity in herb and standard determination in Thai herb books to develop a sustainable quality of life, the result of study in 14 herbs do not find sample of heavy metal., by quantity of heavy contamination of 4 kinds: Cd, Co, Fe and Pb have lower than standard of 2 organizations: Thai herb standard, and World Health Organization, from the test 14 herbs have Fe in every part of herbs and all 14 kinds has Fe that is necessary for our health.

Keywords: herbs plants, heavy metal, Dusit district, sustainable quality of life

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Authors: Brian Yuliarto, Ni Luh Wulan Septiani

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Carbon nanotubes are one of the carbon nanomaterial that very popular in the field of gas sensors. It has unique properties, large surface area and has hollow structure that makes its potentially used as a gas sensor. Several attempts have been made to improve the sensitivity and selectivity of CNTs by modifying CNTs with a noble metals, metal oxides and polymers. From these studies, there are evidents that modification of CNTs with these materials can improve the sensitivity and selectivity of CNTs against some harmful gases. Decorating carbon nano tubes with metal oxides improve CNTs with the highest sensitivity and increased sensitivity of polymer/CNTs is higher than the metal/CNTs. The used of metal in CNTs aims to accelerate the reaction surface and as channel for electrons path from or to the CNTs. The used of metal oxides on CNTs built a p-n junction that can increase sensitivity. While the addition of polymer can increase the charge carriers density in CNTs.

Keywords: carbon nanotubes, gas sensors, modification of CNT, sensitivity

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Authors: Awais Ahmad Khan, Emad Abouel Nasr, H. M. A. Hussein, Abdulrahman Al-Ahmari

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Sheet-metal parts have been widely applied in electronics, communication and mechanical industries in recent decades; but the advancement in sheet-metal part design and manufacturing is still behind in comparison with the increasing importance of sheet-metal parts in modern industry. This paper presents a methodology for automatic extraction of some common 2D internal sheet metal features. The features used in this study are taken from Unipunch ™ catalogue. The extraction process starts with the data extraction from STEP file using an object oriented approach and with the application of suitable algorithms and rules, all features contained in the catalogue are automatically extracted. Since the extracted features include geometry and engineering information, they will be effective for downstream application such as feature rebuilding and process planning.

Keywords: feature extraction, internal features, punch shapes, sheet metal

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Authors: Todor Penchev, Dimitar Karastojanov, Ivan Altaparmakov

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For briquetting of metal chips are used hydraulic and mechanical presses. The density of the briquettes in this case is about 60% - 70 % on the density of solid metal. In this work are presented the results of experimental studies for briquetting of metal chips, by using a new technology for impact briquetting. The used chips are by Armco iron, steel, cast iron, copper, aluminum and brass. It has been found that: (i) in a controlled impact the density of the briquettes can be increases up to 30%; (ii) at the same specific impact energy Es (J/sm3) the density of the briquettes increases with increasing of the impact velocity; (iii), realization of the repeated impact leads to decrease of chips density, which can be explained by distribution of elastic waves in the briquette.

Keywords: briquetting, chips briquetting, impact briquetting, controlled impact

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Authors: Ha-Guk Jeong, Jong-Beom Lee

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Cladding process is very typical technology for manufacturing composite materials by the hydrostatic extrusion. Because there is no friction between the metal and the container, it can be easily obtained in uniform flow during the deformation. The general manufacturing process for a metal-matrix composite in the solid state, mixing metal powders and ceramic powders with a suited volume ratio, prior to be compressed or extruded at the cold or hot condition in a can. Since through a plurality of unit processing steps of dispersing the materials having a large difference in their characteristics and physical mixing, the process is complicated and leads to non-uniform dispersion of ceramics. It is difficult and hard to reach a uniform ideal property in the coherence problems at the interface between the metal and the ceramic reinforcements. Metal hybrid composites, which presented in this report, are manufactured through the traditional plastic deformation processes like hydrostatic extrusion, caliber-rolling, and drawing. By the previous process, the realization of uniform macro and microstructure is surely possible. In this study, as a constituent material, aluminum, copper, and titanium have been used, according to the component ratio, excellent characteristics of each material were possible to produce a metal hybrid composite that appears to maximize. MgB₂ superconductor wire also fabricated via the same process. It will be introduced to their unique artistic and thermal characteristics.

Keywords: cladding process, metal-hybrid composites, hydrostatic extrusion, electronic/thermal characteristics

Procedia PDF Downloads 179

Authors: B. V. Feujofack Kemda, N. Barka, M. Jahazi, D. Osmani

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Automobile manufacturers are constantly seeking means to reduce the weight of car bodies. The usage of several steel grades in auto body assembling has been found to be a good technique to enlighten vehicles weight. This few years, the usage of dual phase (DP) steels, transformation induced plasticity (TRIP) steels and boron steels in some parts of the auto body have become a necessity because of their lightweight. However, these steels are martensitic, when they undergo a fast heat treatment, the resultant microstructure is essential, made of martensite. Resistance spot welding (RSW), one of the most used techniques in assembling auto bodies, becomes problematic in the case of these steels. RSW being indeed a process were steel is heated and cooled in a very short period of time, the resulting weld nugget is mostly fully martensitic, especially in the case of DP, TRIP and boron steels but that also holds for plain carbon steels as AISI 1010 grade which is extensively used in auto body inner parts. Martensite in its turn must be avoided as most as possible when welding steel because it is the principal source of brittleness and it weakens weld nugget. Thus, this work aims to find a mean to reduce martensite fraction in weld nugget when using RSW for assembling. The prediction of phase transformation kinetics during RSW has been done. That phase transformation kinetics prediction has been made possible through the modelling of the whole welding process, and a technique called post weld heat treatment (PWHT) have been applied in order to reduce martensite fraction in the weld nugget. Simulation has been performed for AISI 1010 grade, and results show that the application of PWHT leads to the formation of not only martensite but also ferrite, bainite and pearlite during the cooling of weld nugget. Welding experiments have been done in parallel and micrographic analyses show the presence of several phases in the weld nugget. Experimental weld geometry and phase proportions are in good agreement with simulation results, showing here the validity of the model.

Keywords: resistance spot welding, AISI 1010, modeling, post weld heat treatment, phase transformation, kinetics

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Authors: Ammar Neshati, Elham Hamidi Shishavan

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Statement of Problem: The increase in the use of metal-ceramic restorations and a high prevalence of porcelain chipping entails introducing an alloy which is more compatible with porcelain and which causes a stronger bond between the two. This study is to compare shear bond strength of three base-metal alloys and one noble alloy with the common VMK Master Porcelain. Materials and Method: Three different groups of base-metal alloys (Ni-cr-T3, Super Cast, Verabond) and one group of noble alloy (x-33) were selected. The number of alloys in each group was 15. All the groups went through the casting process and change from wax pattern into metal disks. Then, VMK Master Porcelain was fired on each group. All the specimens were put in the UTM and a shear force was loaded until a fracture occurred. The fracture force was then recorded by the machine. The data was subjected to SPSS Version 16 and One-Way ANOVA was run to compare shear strength between the groups. Furthermore, the groups were compared two by two through running Tukey test. Results: The findings of this study revealed that shear bond strength of Ni-Cr-T3 alloy was higher than the three other alloys (94 Mpa or 330 N). Super Cast alloy had the second greatest shear bond strength (80. 87 Mpa or 283.87 N). Both Verabond (69.66 Mpa or 245 N) and x-33 alloys (66.53 Mpa or 234 N) took the third place. Conclusion: Ni-Cr-T3 with VMK Master Porcelain has the greatest shear bond strength. Therefore, the use of this low-cost alloy is recommended in metal-ceramic restorations.

Keywords: shear bond, base-metal alloy, noble alloy, porcelain

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Authors: Abdulhakeem Sulyman, Olukotun Zainab, Hammed Abdulquadri

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Lipases (triacylglycerol acyl hydrolases) (EC 3.1.1.3) are class of enzymes that catalyses the hydrolysis of triglycerides to glycerol and free fatty acids. They account for up to 10% of the enzyme in the market and have a wide range of applications in biofuel production, detergent formulation, leather processing and in food and feed processing industry. This research was conducted to study the effect of some metal ions on the activity of purified lipase produced by Aspergillus niger cultured on Vitellaria paradoxa shells. Purified lipase in 12.5 mM p-NPL was incubated with different metal ions (Zn²⁺, Ca²⁺, Mn²⁺, Fe²⁺, Na⁺, K⁺ and Mg²⁺). The final concentrations of metal ions investigated were 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0 mM. The results obtained from the study showed that Zn²⁺, Ca²⁺, Mn²⁺ and Fe²⁺ ions increased the activity of lipase up to 3.0, 3.0, 1.0, and 26.0 folds respectively. Lipase activity was partially inhibited by Na⁺ and Mg²⁺ with up to 88.5% and 83.7% loss of activity respectively. Lipase activity was also inhibited by K⁺ with up to 56.7% loss in the activity as compared to in the absence of metal ions. The study concluded that lipase produced by Aspergillus niger cultured on Vitellaria paradoxa shells can be activated by the presence of Zn²⁺, Ca²⁺, Mn²⁺ and Fe²⁺ and inhibited by Na⁺, K⁺ and Mg²⁺.

Keywords: Aspergillus niger, Vitellaria paradoxa, lipase, metal ions

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Authors: Khachatur V. Nerkararyan, Sergey I. Bozhevolnyi

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We investigate relaxation dynamics of a quantum dipole emitter (QDE), e.g., a molecule or quantum dot, located near a metal nanoparticle (MNP) exhibiting a dipolar localized surface plasmon (LSP) resonance at the frequency of the QDE radiative transition. It is shown that under the condition of the QDE-MNP characteristic relaxation time being much shorter than that of the QDE in free-space but much longer than the LSP lifetime. It is also shown that energy dissipation in the QDE-MNP system is relatively weak with the probability of the photon emission being about 0.75, a number which, rather surprisingly, does not explicitly depend on the metal absorption characteristics. The degree of entanglement measured by the concurrency takes the maximum value, while the distances between the QDEs and metal ball approximately are equal.

Keywords: metal nanoparticle, localized surface plasmon, quantum dipole emitter, relaxation dynamics

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Authors: V. J. Pillewan, D. N. Raut, K. N. Patil, D. K. Shinde

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Forging, milling, turning, grinding and shaping etc. are the various industrial manufacturing processes which generate the metal waste. Grinding is extensively used in the finishing operation. The waste generated contains significant impurities apart from the metal particles. Due to these significant impurities, it becomes difficult to process and gets usually dumped in the landfills which create environmental problems. Therefore, it becomes essential to reuse metal waste to create value added products. Powder injection molding process is used for producing the porous metal matrix framework. This paper discusses the presented design of the porous framework to be used for the liquid filter application. Different parameters are optimized to obtain the better strength framework with variable porosity. Carbon nanotubes are used as reinforcing materials to enhance the strength of the metal matrix framework.

Keywords: grinding waste, powder injection molding (PIM), carbon nanotubes (CNTs), matrix composites (MMCs)

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Authors: Vasileios Gerakis, Fontounasios Christos, Alkis Hatzopoulos

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A study of the impact of metal guard rings on the coupling between two square metal pads is presented. The structure is designed over a bulk silicon substrate with epitaxial layer, so the coupling through the substrate is also involved. A lightly doped profile is adopted and is simulated by means of an electromagnetic simulator for various pad distances and different metal layers, assuming a 65 nm bulk CMOS technology. The impact of various guard ring design (geometrical) parameters is examined. Furthermore, the increase of isolation (resulting in reduction of the noise coupling) between the pads by cutting the ring, or by using multiple rings, is also analyzed. S parameters are used to compare the various structures.

Keywords: guard rings, metal pad coupling, millimeter wave frequencies, substrate noise,

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Authors: Ajay Sidana, Kulbir Singh Sandhu, Balwinder Singh Sidhu

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Joining of dissimilar non-ferrous alloys like aluminium and magnesium alloys becomes important in various automobile and aerospace applications due to their low density and good corrosion resistance. Friction Stir Welding (FSW), a solid state joining process, successfully welds difficult to weld similar and dissimilar aluminum and magnesium alloys. Two tool rotation speeds were selected by keeping the transverse speed constant to weld similar and dissimilar alloys. Similar(Al to Al) and Dissimilar(Al to Mg) weld joints were obtained by FSW. SEM scans revealed that higher tool rotation fragments the coarse grains of base material into fine grains in the weld zone. Also, there are less welding defects in weld joints obtained with higher tool rotation speed. The material of dissimilar alloys was mixed with each other forming recrystallised new intermetallics. There was decrease in hardness of similar weld joint however there is significant increase in hardness of weld zone in case of dissimilar weld joints due to stirring action of tool and formation of inter metallics. Tensile tests revealed that there was decrease in percentage elongation in both similar and dissimilar weld joints.

Keywords: aluminum alloys, magnesium alloys, friction stir welding, microstructure, mechanical properties

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Authors: Fatemeh Safdari, Amirnaser Shamkhali, Gholamabbas Parsafar

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Carbon nanostructures are of great importance in academic research and industry, which can be mentioned to chemical sensors, catalytic processes, pharmaceutical and environmental issues. Common point in all of these applications is the occurrence of adsorption of molecules on these structures. Important carbon nanostructures in this case are mainly nanotubes and graphene. To modify pure graphene, recently, many experimental and theoretical studies have carried out to investigate of metal adsorption on graphene. In this work, the adsorption of CO molecules on pure graphene and on metal adatom on graphene surface has been simulated based on density functional theory (DFT). All calculations were performed by PBE functional and Troullier-Martins pseudopotentials. Density of states (DOS) for graphene-CO, graphen and CO around the Fermi energy has been moved and very small mixing occured which implies the physisorption of CO on the bare graphen surface. While, the results have showed that CO adsorption on transition-metal adatom on graphene surface is chemisorption.

Keywords: adsorption, density functional theory, graphene, metal adatom

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Authors: Sukru Dursun, Zeynep Cansu Ayturan, Mostafa Maroof

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Metal coating which is important method used for protecting metals against oxidation and corrosion, decreasing friction, protecting metals from chemicals, easing cleaning of the metals. There are several methods used for metal coating such as hot-dip galvanizing, thermal spraying, electroplating and sherardizing. Method which will be used for metal coating depends on the type of metal. The materials mostly used for coating are zinc, nickel, brass, chrome, gold, cadmium, copper, brass, and silver. Within these materials, chrome ion has significant negative impacts on human, other living organisms and environment. Moreover, especially on human chrome may cause lung cancer, stomach ulcer, kidney and liver function disorders and death. Therefore, wastewaters of metal coating industry including chrome should be treated very carefully. In this study, wastewater containing chrome produced by metal coating industry was analysed with phytotoxicity method that is based on measuring the reaction of some plant species against different concentrations of chrome solution. Main plants used for phytotoxicity tests are Lepidium sativum and Lemna minor. Owing to phytotoxicity test, assessing the negative effects of chrome which may harm plants and offering more accurate wastewater treatment techniques against chromium wastewater is possible. Furthermore, the results taken from phytotoxicity tests were analysed with respect to their variance and their importance against different concentrations of chrome solution were determined.

Keywords: metal coating wastewater, chrome, phytotoxicity, Lepidium sativum, Lemna minor

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Authors: Sobia Mushtaq, Firdaus E. Bareen, Asma Tayyeb

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This study conducted to investigate the metal biosorption potential of indigenous Trichoderma species (T. harzianum KS05T01, T. longibrachiatum KS09T03, Trichoderma sp KS17T09., T. viridi KS17T011, T. atrobruneo KS21T014, and T. citrinoviride) that have been isolated from contaminated soil of Kasur Tannery Waste Management Agency. The effect of different biosorption parameters as initial metal ion concentration, pH, contact time , and temperature of incubation was investigated on the biosorption potential of these species. The metal removal efficiency and (E%) and metal uptake capacity (mg/g) increased along with the increase of initial metal concentration in media. The Trichoderma species can tolerate and survive under heavy metal stress up to 800mg/L. Among the two isotherm models were applied on the biosorption data, Langmuir isotherm model and Freundlich isotherm model, maximum correlation coefficients values (R 2 ) of 1was found for Langmuir model, which showed the better fitted model for the Trichoderma biosorption. The metal biosorption was increased with the increase of temperature and pH of the media. The maximum biosorption was observed between 25-30 o C and at pH 6.-7.5, while the biosorption rate was increased from 3-6 days of incubation, and then the rate of biosorption was slowed down. The biosorption data was better fitted for Pseudo kinetic first order during the initial days of biosorption. Thermodynamic parameters as standard Gibbs free energy (G), standard enthalpy change (H), and standard entropy (S) were calculated. The results confirmed the heavy metal biosorption by Trichoderma species was endothermic and spontaneous reaction in nature. The FTIR spectral analysis and SEM-EDX analysis of the treated and controlled mycelium revealed the changes in the active functional sites and morphological variations of the outer surface. The data analysis envisaged that high metal tolerance exhibited by Trichoderma species indicates its potential as efficacious and successful mediator for bioremediation of the heavy metal polluted environments.

Keywords: heavy metal, fungal biomass, biosorption, kinetics

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Authors: Bikas Chandra Bhattarai

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Child labour is the serious issue all over the world. In Nepal, many children are working in different structured and unstructured sector. Metal fabrication is one of the sectors where many children are involved. The present study is carried out to focus on the overall socio-economic condition, psychological aspect, working environment condition and welfare of the child labour. Metal fabrication factories from Kirtipur, Chovar Area, Gongabu, Sitapaila and Sankhamul area of Kathmandu municipality were selected for the study. The structured questionnaire was prepared, and overall 55 children under age 16 were interviewed. Working in metal fabrication factory is risky job for children. The main reason behind child labour is poverty. The working environment in the metal fabrication factory was not found satisfactory. Children are exposed to various types of physical and chemical hazards. Factories are not paying proper attention to safety condition at the workplace. Large number of children is attracted towards smoking and drinking alcohol leading to unnecessary expense of their income. There should be the provision of regular health check up and insurance to the working children. Monitoring from the government level should be implemented for the betterment of working children.

Keywords: child labour, Kathmandu, Nepal, metal fabrication

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Authors: Ahmed K. Youssef, Shawkat M. B. Aly

Abstract:

The interaction between ciprofloxacin and bovine serum albumin (BSA) was investigated by UV-Visible absorption and fluorescence spectroscopy. The influence of Cu²⁺ Ca²⁺, Co²⁺, and Fe³⁺ on the Cip-BSA interaction was investigated. The quenching of the BSA fluorescence emission in presence of ciprofloxacin as well as the influence of metal ions on the interaction was analyzed using the Stern-Volmer equation. The Stern-Volmer quenching constant, Kₛᵥ was calculated in presence and absence of the metal ions at the physiological pH of 7.4 using phosphate buffer. The experimental results showed that interaction mainly static in nature and quenching rate constant is decreased in presence of the studied metal ions with exception of Cu²⁺ ions. The decrease observed in the Kₛᵥ values in presence of Co²⁺, Ca²⁺, and Fe³⁺ can be understood on basis of competition between these metal and Cip when both of them existed in the BSA solution. Cu²⁺ induces interaction between Cip and BSA at faster quenching rates as inferred from the observed increase in the Kₛᵥ value. This allowed us to propose that copper (II) ions are directly involved in the process of Cip binding to BSA. The binding constant for Cip on BSA was determined and the metal ions effect on it was examined as well and their values were in line with the Kₛᵥ values.

Keywords: bovine serum albumin, ciprofloxacin, fluorescence, metal ions effect

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Authors: Kirit Siddhapara, Dimple Shah

Abstract:

In this research, we have studied the doping behaviors of two transition metal ion dopants on the crystal phase, particle sizes, XRD patterns, EDAX spectra, and photoreactivity of TiO2 nanoparticles. The crystalline size of TiO2 is close to 4 nm Calculated from (1 0 1) peak by using FWHM method in Scherrer’s equation. Test metal ion concentrations ranged from 1% to 4 at.%, we report the growth of [Fe, Mn]xTiO2 nanocrystals prepared by Sol-Gel technique, followed by freeze-drying treatment at -30°C temperature for 12hrs. The obtained Gel was thermally treated at different temperature like 200°C, 400°C, 600°C, 800°C. Thermal gravimetric analysis (TGA) shows that dopant concentration affects thermal decomposition. The photoreactivities of transition metal ion-doped TiO2 nanoparticles under UV irradiation were quantified by the degradation of formaldehyde.

Keywords: growth from solution, sol-gel method, nanomaterials, oxides, magnetic materials, titanium compounds

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Authors: Se-Mi Lim, Won-Jae Jung, Jin-Sup Kim, Jun-Seok Park, Hyung-Il Chae

Abstract:

This paper presents a current-mode vertical hall device (VHD) structure using metal layers in a CMOS process. The proposed metal layer based vertical hall device (MLVHD) utilizes vertical connection among metal layers (from M1 to the top metal) to facilitate hall effect. The vertical metal structure unit flows a bias current Ibias from top to bottom, and an external magnetic field changes the current distribution by Lorentz force. The asymmetric current distribution can be detected by two differential-mode current outputs on each side at the bottom (M1), and each output sinks Ibias/2 ± Ihall. A single vertical metal structure generates only a small amount of hall effect of Ihall due to the short length from M1 to the top metal as well as the low conductivity of the metal, and a series connection between thousands of vertical structure units can solve the problem by providing NxIhall. The series connection between two units is another vertical metal structure flowing current in the opposite direction, and generates negative hall effect. To mitigate the negative hall effect from the series connection, the differential current outputs at the bottom (M1) from one unit merges on the top metal level of the other unit. The proposed MLVHD is simulated in a 3-dimensional model simulator in COMSOL Multiphysics, with 0.35 μm CMOS process parameters. The simulated MLVHD unit size is (W) 10 μm × (L) 6 μm × (D) 10 μm. In this paper, we use an MLVHD with 10 units; the overall hall device size is (W) 10 μm × (L)78 μm × (D) 10 μm. The COMSOL simulation result is as following: the maximum hall current is approximately 2 μA with a 12 μA bias current and 100mT magnetic field; This work was supported by Institute for Information & communications Technology Promotion(IITP) grant funded by the Korea government(MSIP) (No.R7117-16-0165, Development of Hall Effect Semiconductor for Smart Car and Device).

Keywords: CMOS, vertical hall device, current mode, COMSOL

Procedia PDF Downloads 302