Search results for: Heavy Metal Contamination

Authors: Kevlin Govender, Anthony Walker, Glen Bright

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Mass customization is an area of increased importance and the development of rapid tooling applications is pivotal to the success of mass customization. This paper presents a laminated object manufacturing (LOM) process for rapid tooling. The process is termed 3D metal laminate printing and utilizes domestic-grade aluminum foil and epoxy for layered manufacturing. A detailed explanation of the process is presented to produce complex metal laminated composite parts. Aluminum-epoxy composite specimens were manufactured from 0.016mm aluminum and subjected to tensile tests to determine the mechanical properties of the manufactured composite in relation to solid metal specimens. The fracture zone of the specimens was analyzed under scanning electron microscopy (SEM) in order to characterize the fracture mode and study the interfacial bonding of the manufactured laminate specimens.

Keywords: 3D metal laminate printer, aluminum-epoxy composite, laminated object manufacturing, rapid tooling

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Authors: Rabia Hunky, Hayat Kalifa, Bai

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The wettability of carbonate reservoirs has been widely recognized as an important parameter in oil recovery by flooding technology. Many surfactants have been studied for this application. However, the importance of wettability alteration in sandstone reservoirs by surfactant has been poorly studied. In this paper, our recent study of the relationship between rock surface wettability and cumulative oil recovery for sandstone cores is reported. In our research, it has been found there is a good agreement between the wettability and oil recovery. Nonionic surfactants, Tomadol® 25-12 and Tomadol® 45-13, are very effective in wettability alteration of sandstone core surface from highly oil-wet conditions to water-wet conditions. By spontaneous imbibition test, Interfacial tension, and contact angle measurement these two surfactants exhibit the highest recovery of the synthetic oil made with heavy oil. Based on these experimental results, we can further conclude that the contact angle measurement and imbibition test can be used as rapid screening tools to identify better EOR surfactants to increase heavy oil recovery from sandstone reservoirs.

Keywords: EOR, oil gas, IOR, WC, IF, oil and gas

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Authors: Noura Kichou, Manel Tafergguenit, Nabila Ghechtouli, Zakia Hank

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The aim of this work is to synthesize, characterize and evaluate the biological activity of two Ligands : glyoxime and dimethylglyoxime, and their metal Ni(II) chelates. The newly chelates were characterized by elemental analysis, IR, EPR, nuclear magnetic resonances (1H and 13C), and biological activity. The antibacterial and antifungal activities of the ligands and its metal complexes were screened against bacterial species (Staphylococcus aureus, Bacillus subtilis, and Escherichia coli) and fungi (Candida albicans). Ampicillin and amphotericin were used as references for antibacterial and antifungal studies. The activity data show that the metal complexes have a promising biological activity comparable with parent free ligand against bacterial and fungal species. A structural, energetic, and electronic theoretical study was carried out using the DFT method, with the functional B3LYP and the gaussian program 09. A complete optimization of geometries was made, followed by a calculation of the frequencies of the normal modes of vibration. The UV spectrum was also interpreted. The theoretical results were compared with the experimental data.

Keywords: glyoxime, dimetylglyoxime, nickel, antibacterial activity

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Authors: Noura Kichou, Manel Tafergguenit, Nabila Ghechtouli, Zakia Hank

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The aim of this work is to synthesize, characterize and evaluate the biological activity of two Ligands: glyoxime and dimethylglyoxime, and their metal Ni(II) chelates. The newly chelates were characterized by elemental analysis, IR, EPR, nuclear magnetic resonances (1H and 13C), and biological activity. The antibacterial and antifungal activities of the ligands and its metal complexes were screened against bacterial species (Staphylococcus aureus, Bacillus subtilis, and Escherichia coli) and fungi (Candida albicans). Ampicillin and amphotericin were used as references for antibacterial and antifungal studies. The activity data show that the metal complexes have a promising biological activity comparable with parent free ligand against bacterial and fungal species. A structural, energetic, and electronic theoretical study was carried out using the DFT method, with the functional B3LYP and the gaussian program 09. A complete optimization of geometries was made, followed by a calculation of the frequencies of the normal modes of vibration. The UV spectrum was also interpreted. The theoretical results were compared with the experimental data.

Keywords: glyoxime, dimetylglyoxime, nickel, antibacterial activity

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Authors: Rezaul K. Sk., Mohammad Ashiq, Avinash K. Srivastava

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The use of radiation shielding technology ranging from EMI to high energy gamma rays in various areas such as devices, medical science, defense, nuclear power plants, medical diagnostics etc. is increasing all over the world. However, exposure to different radiations such as X-ray, gamma ray, neutrons and EMI above the permissible limits is harmful to living beings, the environment and sensitive laboratory equipment. In order to solve this problem, there is a need to develop effective radiation shielding materials. Conventionally, lead and lead-based materials are used in making shielding materials, as lead is cheap, dense and provides very effective shielding to radiation. However, the problem associated with the use of lead is its toxic nature and carcinogenic. So, to overcome these drawbacks, there is a great need for lead-free radiation shielding materials and that should also be economically sustainable. Therefore, it is necessary to look for the synthesis of radiation-shielding glass by using other heavy metal oxides (HMO) instead of lead. The lead-free BaO-doped TeZnCaB glass systems have been synthesized by the traditional melt-quenching method. X-ray diffraction analysis confirmed the glassy nature of the synthesized samples. The densities of the developed glass samples were increased by doping the BaO concentration, ranging from 4.292 to 4.725 g/cm3. The vibrational and bending modes of the BaO-doped glass samples were analyzed by Raman spectroscopy, and FTIR (Fourier-transform infrared spectroscopy) was performed to study the functional group present in the samples. UV-visible characterization revealed the significance of optical parameters such as Urbach’s energy, refractive index and optical energy band gap. The indirect and direct energy band gaps were decreased with the BaO concentration whereas the refractive index was increased. X-ray attenuation measurements were performed to determine the radiation shielding parameters such as linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half value layer (HVL), tenth value layer (TVL), mean free path (MFP), attenuation factor (Att%) and lead equivalent thickness of the lead-free BaO-doped TeZnCaB glass system. It was observed that the radiation shielding characteristics were enhanced with the addition of BaO content in the TeZnCaB glass samples. The glass samples with higher contents of BaO have the best attenuation performance. So, it could be concluded that the addition of BaO into TeZnCaB glass samples is a significant technique to improve the radiation shielding performance of the glass samples. The best lead equivalent thickness was 2.626 mm, and these glasses could be good materials for medical diagnostics applications.

Keywords: heavy metal oxides, lead-free, melt-quenching method, x-ray attenuation

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Authors: Ertuğ Yıldırım, Dile Kara, Salih Zeki Yıldız

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Metal containing polymers (MCPs) are macro molecules usually containing metal-ligand coordination units and are a multidisciplinary research field mainly based at the interface between coordination chemistry and polymer science. The progress of this area has also been reinforced by the growth of several other closely related disciplines including macro molecular engineering, crystal engineering, organic synthesis, supra molecular chemistry and colloidal and material science. Schiff base ligands are very effective in constructing supra molecular architectures such as coordination polymers, double helical and triple helical complexes. In addition, Schiff base derivatives incorporating a fluorescent moiety are appealing tools for optical sensing of metal ions. MCPs are well-known systems in which the combinations of local parameters are possible by means of fluoro metric techniques. Generally, without incorporation of the fluorescent groups with polymers is unspecific, and it is not useful to analyze their fluorescent properties. Therefore, it is necessary to prepare a new type epoxy polymers with fluorescent groups in terms of metal sensing prop and the other photo chemical applications. In the present study metal containing polymers were prepared via poly functional monomeric Schiff base metal chelate complexes in the presence of dis functional monomers such as diglycidyl ether Bisphenol A (DGEBA). The synthesized complexes and polymers were characterized by FTIR, UV-VIS and mass spectroscopies. The preparations of epoxy polymers have been carried out at 185 °C. The prepared composites having sharp and narrow excitation/emission properties are expected to be applicable in various systems such as heat-resistant polymers and photo voltaic devices. The prepared composite is also ideal for various applications, easily prepared, safe, and maintain good fluorescence properties.

Keywords: Schiff base ligands, crystal engineering, fluorescence properties, Metal Containing Polymers (MCPs)

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Authors: Jukka Törrönen

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In the article, we examine the interplay between the practices of heavy drinking and exercise among young people as patterned around the ‘social’ and ‘physical health’ approaches. The comparison helps us to clarify why young people are currently drinking less than earlier and how the neoliberal healthism discourse, as well as the feminine tradition of taking care of one’s body, are modifying young people’s heavy drinking practices. The data is based on interviews (n = 56) in Sweden among 15-16-year-olds and 18˗19-year-olds. By drawing on Pierre Bourdieu’s concepts of habitus, field, and capital, we examine what kinds of resources of wellbeing young people accumulate in the fields of heavy drinking and exercise, how these resources carry symbolic value for distinction, and what kind of health-related habitus they imply. The analysis suggests that as heavy drinking is no longer able to stand as a practice through which one may acquire capital that is more valuable than the capital acquired in other fields, this lessens peer pressure to drink among young people. Our analysis further shows that the healthism discourse modifies young people’s heavy drinking practices both from inside and from outside. The interviewees translate the symbolic value of healthism discourse to social vulnerability and deploy it for the purposes of increasing one’s social status among peers. Moreover, our analysis demonstrates that the social spaces and positions in intoxication and exercise are shaped by gendered dualisms of masculine dominance. However, while the interviewees naturalize the gender binaries in intoxication as based on biological drives, they understand gender binaries in exercise as normative social constructions of neoliberal society. As these binaries emphasize the struggle for recognition of the symbolic value of bodily look, they may shift young men’s attention from risk-taking to issues that traditionally have been female concerns.

Keywords: young people, decline in drinking , health, intoxication, exercise, Bourdieu

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Authors: Lav Kesharwani, Nalini Shankar, A. K. Gupta

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A serial number is a unique code assigned for identification of a single unit. Serial number are present on many objects. In an attempt to hide the identity of the numbered item, the numbers are often obliterated or removed by mechanical methods. The present work was carried out with an objective to develop less toxic, less time consuming, more result oriented chemical etching reagent for restoration of serial number on the copper metal plate. Around nine different reagents were prepared using different combination of reagent along with standard reagent and it was applied over 50 erased samples of copper metal and compared it with the standard reagent for restoration of erased marks. After experiment, it was found that the prepared Etching reagent no. 3 (10 g FeCl3 + 20 ml glacial acetic acid + 100 ml distilled H2O) showed the best result for restoration of erased serial number on the copper metal plate .The reagent was also less toxic and less time consuming as compared to standard reagent (19 g FeCl3 + 6 ml cans. HCl + 100 ml distilled H2O).

Keywords: serial number restoration, copper plate, obliteration, chemical method

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Authors: Nida Rabab

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The present study was conducted to assess the Impact on Vegetables Irrigated with Municipal and Industrial wastewater from Korangi Drain near IoBM, Karachi. Some vegetables are grown using sewage and industrial wastewater laden with alarmingly high levels of heavy metals and bacteriological contamination. Maximum concentration of lead was found in spinach 8.20 mg/l as against safe limits of 0.01 mg/l and maximum nickel concentration was found in banana 3.114 mg/l as against 0.02 mg/l, whereas all vegetables were invariably bacteriologically contaminated much beyond safe limits. Appropriate legislations in Sindh and competent manpower for rigorous monitoring to gage the harmful impact on vegetables grown with untreated municipal and industrial wastewater to effectively combat the problems of growing vegetables. The emptying of untreated municipal and industrial wastewater through Korangi Drain in fresh water bodies into Karachi cost should be banned to save the coast becoming hypoxic causing irreparable loss to marine life.

Keywords: laden, concentration, hypoxic, vegetables

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Authors: Valentina Paolucci, Jessica De Santis, Vittorio Ricci, Giacomo Giorgi, Carlo Cantalini

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Despite their potential in gas sensing applications, the major drawback of 2D exfoliated metal dichalcogenides (MDs) is that they suffer from spontaneous oxidation in air, showing poor chemical stability under dry/wet conditions even at room temperature, limiting their practical exploitation. The aim of this work is to validate a synthesis strategy allowing microstructural and electrical stabilization of the oxides that inevitably form on the surface of 2D dichalcogenides. Taking advantage of spontaneous oxidation of MDs in air, we report on liquid phase exfoliated 2D-SnSe2 flakes annealed in static air at a temperature below the crystallization temperature of the native a-SnO2 oxide. This process yields a new class of 2D Layered Amorphous Metal Oxides Sensors (LAMOS), specifically few-layered amorphous a-SnO2, showing excellent gas sensing properties. Sensing tests were carried out at low operating temperature (i.e. 100°C) by exposing a-SnO2 to both oxidizing and reducing gases (i.e. NO2, H2S and H2) and different relative humidities ranging from 40% to 80% RH. The formation of stable nanosheets of amorphous a-SnO2 guarantees excellent reproducibility and stability of the response over one year. These results pave the way to new interesting research perspectives out considering the opportunity to synthesize homogeneous amorphous textures with no grain boundaries, no grains, no crystalline planes with different orientations, etc., following gas sensing mechanisms that likely differ from that of traditional crystalline metal oxide sensors. Moreover, the controlled annealing process could likely be extended to a large variety of Transition Metal Dichalcogenides (TMDs) and Metal Chalcogenides (MCs), where sulfur, selenium, or tellurium atoms can be easily displaced by O2 atoms (ΔG < 0), enabling the synthesis of a new family of amorphous interfaces.

Keywords: layered 2D materials, exfoliation, lamos, amorphous metal oxide sensors

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Authors: A. G. More

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Bioelectrochemical system (BES) is an alternative technology for chromium Cr (VI) removal from industrial wastewater to overcome the existing drawbacks of high chemical and energy consumption by conventional metal removal technologies. A well developed anaerobic sludge was developed in laboratory and used in the batch study of BES at different Cr (VI) concentrations (10, 20, 50, and 50 mg/L) with different COD concentrations (500, 1000, 1500 and 2000 mg/L). Sodium acetate was used as carbon source, whereas Cr (VI) contaminated synthetic wastewater was prepared and added to the cathode chamber. Initially, operating conditions for the BES experiments were optimized. During the study, optimum cathode pH of 2, whereas optimum HRT of 72 hr was obtained. During the study, cathode pH 2 ± 0.1 showed maximum chromium removal efficicency (CRE) of 88.36 ± 8.16% as compared to other pH (1-7) in the cathode chamber. Maximum CRE obtained was 85.93 ± 9.62% at 40°C within the temperature range of 25°C to 45°C. Conducting the BES experiments at optimized operating conditions, CRE of 90.2 %, 93.7 %, 83.75 % and 74.6 % were obtained at cathodic Cr concentration of 10, 20, 50, and 50 mg/L, respectively. BES is a sustainable, energy efficient technology which can be suitably used for metal removal from industrial wastewater.

Keywords: bioelectrochemical system, metal removal, microorganisms, pH and temperature, substrate

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Authors: Jian Huang, Weixin Qian, Hongfang Ma, Haitao Zhang, Weiyong Ying

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Cobalt catalysts were supported on extruded silica carrier and different-type (SiO₂, γ-Al₂O₃) commercial supports with different shapes and sizes to produce heavy hydrocarbons for Fischer-Tropsch synthesis. The catalysts were characterized by N₂ physisorption and H₂-TPR. The catalytic performance of the catalysts was tested in a fixed bed reactor. The results of Fischer-Tropsch synthesis performance showed that the cobalt catalyst supported on spherical silica supports displayed a higher activity and a higher selectivity to C₅⁺ products, due to the fact that the active components were only distributed in the surface layer of spherical carrier, and the influence of gas diffusion restriction on catalytic performance was weakened. Therefore, it can be concluded that the eggshell cobalt catalyst was superior to precious metals modified catalysts in the synthesis of heavy hydrocarbons.

Keywords: fischer-tropsch synthesis, cobalt catalyst, support shape, heavy hydrocarbons

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Authors: Luana Guerra, Silvio C. Sampaio, Vladimir Pavan Margarido, Ralpho R. Reis

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Brazil is the world's largest consumer of pesticides. The excessive use of these compounds has negative impacts on animal and human life, the environment, and food security. Bees, crucial for pollination, are exposed to pesticides during the collection of nectar and pollen, posing risks to their health and the food chain, including honey contamination. Aquatic sediments are also affected, impacting water quality and the microbiota. Therefore, the analysis of aquatic sediments and bee honey is essential to identify environmental contamination and monitor ecosystems. The aim of this study was to use samples of honey from honeybees (Apis mellifera) and aquatic sediment as bioindicators of environmental contamination by pesticides and their relationship with agricultural use in the surrounding areas. The sample collections of sediment and honey were carried out in two stages. The first stage was conducted in the Bituruna municipality region in the second half of the year 2022, and the second stage took place in the regions of Laranjeiras do Sul, Quedas do Iguaçu, and Nova Laranjeiras in the first half of the year 2023. In total, 10 collection points were selected, with 5 points in the first stage and 5 points in the second stage, where one sediment sample and one honey sample were collected for each point, totaling 20 samples. The honey and sediment samples were analyzed at the Laboratory of the Paraná Institute of Technology, with ten samples of honey and ten samples of sediment. The selected extraction method was QuEChERS, and the analysis of the components present in the sample was performed using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The pesticides Azoxystrobin, Epoxiconazole, Boscalid, Carbendazim, Haloxifope, Fomesafen, Fipronil, Chlorantraniliprole, Imidacloprid, and Bifenthrin were detected in the sediment samples from the study area in Laranjeiras do Sul, Paraná, with Carbendazim being the compound with the highest concentration (0.47 mg/kg). The honey samples obtained from the apiaries showed satisfactory results, as they did not show any detection or quantification of the analyzed pesticides, except for Point 9, which had the fungicide tebuconazole but with a concentration Keywords: contamination, water research, agrochemicals, beekeeping activity

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Authors: H. Aljabiry, L. Bailey, S. Young

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Qatar is a desert with an average temperature 37⁰C, reaching over 40⁰C during summer. Precipitation is uncommon and mostly in winter. Qatar depends on desalination for drinking water and on groundwater and recycled water for irrigation. Water consumption and network leakage per capita in Qatar are amongst the highest in the world; re-use of treated wastewater is extremely limited with only 14% of treated wastewater being used for irrigation. This has led to the country disposing of unwanted water from various sources in lagoons situated around the country, causing concern over the possibility of environmental pollution. Accordingly, our hypothesis underpinning this research is that the quality and quantity of water in lagoons is having an impact on the groundwater reservoirs in Qatar. Lagoons (n = 14) and wells (n = 55) were sampled for both summer and winter in 2018 (summer and winter). Water, adjoining soil and plant samples were analysed for multiple elements by Inductively Coupled Plasma Mass Spectrometry. Organic and inorganic carbon were measured (CN analyser) and the major anions were determined by ion chromatography. Salinization in both the lagoon and the wells was seen with good correlations between Cl⁻, Na⁺, Li, SO₄, S, Sr, Ca, Ti (p-value < 0.05). Association of heavy metals was observed of Ni, Cu, Ag, and V, Cr, Mo, Cd which is due to contamination from anthropological activities such as wastewater disposal or spread of contaminated dust. However, looking at each elements none of them exceeds the Qatari regulation. Moreover, gypsum saturation in the system was observed in both the lagoon and wells water samples. Lagoons and the water of the well are found to be of a saline type as well as Ca²⁺, Cl⁻, SO₄²⁻ type evidencing both gypsum dissolution and salinization in the system. Moreover, Maps produced by Inverse distance weighting showed an increasing level of Nitrate in the groundwater in winter, and decrease chloride and sulphate level, indicating recharge effect after winter rain events. While E. coli and faecal bacteria were found in most of the lagoons, biological analysis for wells needs to be conducted to understand the biological contamination from lagoon water infiltration. As a conclusion, while both the lagoon and the well showed the same results, more sampling is needed to understand the impact of the lagoons on the groundwater.

Keywords: groundwater quality, lagoon, treated wastewater, water management, wastewater treatment, wetlands

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Authors: Joon-Suk Kim, Hae-Woo Lee

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This study discusses the effect of welding heat input on intergranular corrosion of the weld metal of Inconel 625 alloy. A specimen of Inconel 625 with a weld metal that controlled welding heat input was manufactured, and aging heat treatment was conducted to investigate sensitization by chromium carbides. The electrochemical SL and DL EPR experiments, together with the chemical ferric sulfate-sulfuric acid and nitric acid tests, were conducted to determine intergranular corrosion susceptibility between the specimens. In the SL and DL EPR experiments, specimens were stabilized in the weld metal, and therefore intergranular corrosion susceptibility could not be determined. However, in the ferric sulfate-sulfuric acid and nitric acid tests, the corrosion speed increased as heat input increased. This was because the amount of diluted Fe increased as the welding heat input increased, leading to microsegregation between the dendrites, which had a negative effect on the corrosion resistance.

Keywords: Inconel 625, weling, overlay, heat input, intergranular corrosion

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Authors: Chun-Lin Chiang, Che-Yen Lee, Yu-Shan Yeh, Jiunn-Haur Shaw

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Wafer fabrication is a critical part of the semiconductor process, when the finest linewidth with the improvement of technology continues to decline and the structure development from 2D towards to 3D. The nanoparticles contained in the slurry or in the ultrapure water which used for cleaning have a large influence on the manufacturing process. Therefore, semiconductor industry is hoping to find a viable method for on-line detection the nanoparticles size and concentration. The resistive pulse sensing technology is one of the methods that may cover this question. As we know that nanoparticles properties of material differ significantly from their properties at larger length scales. So, we want to clear that the metal and non-metal nanoparticles translocation dynamic when we use the resistive pulse sensing technology. In this study we try to use the finite element method that contains three governing equations to do multiphysics coupling simulations. The Navier-Stokes equation describes the laminar motion, the Nernst-Planck equation describes the ion transport, and the Poisson equation describes the potential distribution in the flow channel. To explore that the metal nanoparticles and the non-metal nanoparticles in different concentration electrolytes, through the nanochannel caused by ion current changes. Then the reliability of the simulation results was verified by resistive pulse sensing test. The existing results show that the lower ion concentration, the greater effect of nanoparticles on the ion concentration in the nanochannel. The conductive spikes are correlated with nanoparticles surface charge. Then we can be concluded that in the resistive pulse sensing technique, the ion concentration in the nanochannel and nanoparticle properties are important for the translocation dynamic, and they have the interactions.

Keywords: multiphysics simulations, resistive pulse sensing, nanoparticles, nanochannel

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Authors: Rashad Al-Gaashani, Viktor Kochkodan, Jenny Lawler

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Physico-chemical activation method wasused to produce high-quality activated carbon (AC) with a large surface area of about 2000 m2/g from low-cost and abundant biomasswastes in Qatar, namely date seeds. X-Ray diffraction (XRD), scanning electron spectroscopy (SEM), energy dispersive X-Ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET) surface area analysis were used to evaluate the AC samples. AC produced from date seeds have a wide range of the pores available, including micro- andnano-pores. This type of AC with a well-developed pore structure may be very attractive for different applications, including air and water purification from micro and nano pollutants. Heavy metalsiron (III) and copper (II) ions were removed from wastewater using the AC producedusinga batch adsorption technique. The AC produced from date seeds biomass wastes show high removal of heavy metals such as iron (III) ions (100%) and copper (II) ions (97.25%). The highest removal of copper (II) ions (100%) with AC produced from date seeds was found at pH 8, whereas the lowest removal (22.63%) occurred at pH 2. The effect of adsorption time, adsorbent dose, pH on the removal of heavy metalswere studied.

Keywords: activated carbon, date seeds, biomass, heavy metals removal, water treatment

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Authors: Thirupathi Thippani, Kothandaraman Ramanujam

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Current research on energy storage has been paid to metal-air batteries, because of attractive alternate energy source for the future. Metal – air batteries have the probability to significantly increase the power density, decrease the cost of energy storage and also used for a long time due to its high energy density, low-level pollution, light weight. The performance of these batteries mostly restricted by the slow kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) on cathode during battery discharge and charge. The ORR and OER are conventionally carried out with precious metals (such as Pt) and metal oxides (such as RuO₂ and IrO₂) as catalysts separately. However, these metal-based catalysts are regularly undergoing some difficulties, including high cost, low selectivity, poor stability and unfavorable to environmental effects. So, in order to develop the active, stable, corrosion resistance and inexpensive bi-functional catalyst material is mandatory for the commercialization of zinc-air rechargeable battery technology. We have attempted and synthesized non-precious metal (NPM) catalysts comprising cobalt and N-doped multiwalled carbon nanotubes (N-MWCNTs-Co) were synthesized by the solid-state pyrolysis (SSP) of melamine with Co₃O₄. N-MWCNTs-Co acts as an excellent electrocatalyst for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), and hence can be used in secondary metal-air batteries and in unitized regenerative fuel cells. It is important to study the OER and ORR at high concentrations of KOH as most of the metal-air batteries employ KOH concentrations > 4M. In the first 16 cycles of the zinc-air battery while using N-MWCNTs-Co, 20 wt.% Pt/C or 20 wt.% IrO₂/C as air electrodes. In the ORR regime (the discharge profile of the zinc-air battery), the cell voltage exhibited by N-MWCNTs-Co was 44 and 83 mV higher (based on 5th cycle) in comparison to of 20 wt.% Pt/C and 20 wt.% IrO₂/C respectively. To demonstrate this promise, a zinc-air battery was assembled and tested at a current density of 0.5 Ag⁻¹ for charge-discharge 100 cycles.

Keywords: oxygen reduction reaction (ORR), oxygen evolution reaction(OER), non-platinum, zinc air battery

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Authors: B. Bouktif, M. Gaidi, M. Benrabha

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Metal-nano particle-assisted chemical etching is an extraordinary developed wet etching method of producing uniform semiconductor nanostructure (nanowires) from the patterned metallic film on the crystalline silicon surface. The metal films facilitate the etching in HF and H2O2 solution and produce silicon nanowires (SiNWs). Creation of different SiNWs morphologies by changing the etching time and its effects on optical and optoelectronic properties was investigated. Combination effect of formed SiNWs and stain etching treatment in acid (HF/HNO3/H2O) solution on the surface morphology of Si wafers as well as on the optical and optoelectronic properties are presented in this paper.

Keywords: semiconductor nanostructure, chemical etching, optoelectronic property, silicon surface

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Authors: Jahede Tekeykhah, Seyed Mohsen Hossini, Gholamali Jalali

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Industrial and traffic activities cause large amounts of heavy metals enter into the atmosphere and the use of plant species can be effective in assessing and reducing air pollution by metals. This study aimed to investigate the adsorption level of heavy metals in leaves of Fraxinus rotundifolia, Robinia, Platanus orientalis, Platycladus orientalis and Pinus eldarica trees in Abidar forest park. For this purpose, samples leaves of the trees were prepared from the contaminated and control areas in each region in 3 stations with 3 replicates in mid-August and finally 90 samples were sent to the laboratory. Then, the concentrations of heavy metals were measured by graphite furnace. To do this, factorial experiment based on a completely randomized design with two factors of location on two levels (contaminated area and control area) and the factor of species on five levels (Fraxinus rotundifolia, Robinia, Platanus orientalis, Platycladus orientalis and Pinus eldarica) with three replications was used. The analysis of collected data was performed by SPSS software and Duncan's multiple range test was used to compare the means. The results showed that the accumulation of all metals in the leaves of most species in the infected area with a significant difference at 95% level was higher than the control area. In the contaminated area, with a significant difference at 5% level, the highest accumulations of metals were observed as the following: lead, cadmium, zinc and manganese in Platanus orientalis, nickel in Fraxinus rotundifolia and copper in Platycladus orientalis.

Keywords: airborne, tree species, heavy metals, absorption, Abidar Forest Park

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Authors: Abdullah Kaymakci, Daniel M. Madyira, Ntokozo Nkwanyana

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The effect of metal transfer modes on mechanical properties of welded 3CR12 stainless steel were investigated. This was achieved by butt welding 10 mm thick plates of 3CR12 in different positions while varying the welding positions for different metal transfer modes. The ASME IX: 2010 (Welding and Brazing Qualifications) code was used as a basis for welding variables. The material and the thickness of the base metal were kept constant together with the filler metal, shielding gas and joint types. The effect of the metal transfer modes on the microstructure and the mechanical properties of the 3CR12 steel was then investigated as it was hypothesized that the change in welding positions will affect the transfer modes partly due to the effect of gravity. The microscopic examination revealed that the substrate was characterized by dual phase microstructure, that is, alpha phase and beta phase grain structures. Using the spectroscopic examination results and the ferritic factor calculation had shown that the microstructure was expected to be ferritic-martensitic during air cooling process. The tested tensile strength and Charpy impact energy were measured to be 498 MPa and 102 J which were in line with mechanical properties given in the material certificate. The heat input in the material was observed to be greater than 1 kJ/mm which is the limiting factor for grain growth during the welding process. Grain growths were observed in the heat affected zone of the welded materials. Ferritic-martensitic microstructure was observed in the microstructure during the microscopic examination. The grain growth altered the mechanical properties of the test material. Globular down hand had higher mechanical properties than spray down hand. Globular vertical up had better mechanical properties than globular vertical down.

Keywords: welding, metal transfer modes, stainless steel, microstructure, hardness, tensile strength

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Authors: Yashfeen Khan, Anees Ahmad

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In the last few decades, nano-composites have been the topic of interest. Presently, the modern era enlightens the synthesis of hybrid nano-composites over their individual counterparts because of higher application potentials and synergism. Recently, CNT hybrids have demonstrated their pronounced capability as effective sorbents for the removal of heavy metal ions (the root trouble) and organic contaminants due to their high specific surface area, enhanced reactivity, and sequestration characteristics. The present abstract discusses removal efficiencies of organic, inorganic pollutants through CNT/PANI/ composites. It also represents the widespread applications of CNT like monitoring biological systems, biosensors, as heat resources for treating cancer, fire retardant applications of polymer/CNT composites etc. And considering the same, this article aims to brief the scenario of CNT-PANI nano-composites.

Keywords: biosensors, CNT, hybrids, polyaniline, synergism

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Authors: Iwona Cieślik, Władysław Migdał, Kinga Topolska, Ewa Cieślik

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The consumption of fish is recommended as a means of preventing serious diseases, especially cardiovascular problems. Fish is known to be a valuable source of protein (rich in essential amino acids), unsaturated fatty acids, fat-soluble vitamins, macro- and microelements. However, it can also contain several contaminants (e.g. pesticides, heavy metals) that may pose considerable risks for humans. Among others, pesticide are of special concern. Their widespread use has resulted in the contamination of environmental compartments, including water. The occurrence of pesticides in the environment is a serious problem, due to their potential toxicity. Therefore, a systematic monitoring is needed. The aim of the study was to determine the organochlorine and organophosphate pesticide residues in fish muscle tissues of the pike (Esox lucius, L.) and the rainbow trout (Oncorhynchus mykkis, Walbaum) by a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method, using Gas Chromatography Quadrupole Mass Spectrometry (GC/Q-MS), working in selected-ion monitoring (SIM) mode. The analysis of α-HCH, β-HCH, lindane, diazinon, disulfoton, δ-HCH, methyl parathion, heptachlor, malathion, aldrin, parathion, heptachlor epoxide, γ-chlordane, endosulfan, α-chlordane, o,p'-DDE, dieldrin, endrin, 4,4'-DDD, ethion, endrin aldehyde, endosulfan sulfate, 4,4'-DDT, and metoxychlor was performed in the samples collected in the Carp Valley (Malopolska region, Poland). The age of the pike (n=6) was 3 years and its weight was 2-3 kg, while the age of the rainbow trout (n=6) was 0.5 year and its weight was 0.5-1.0 kg. Detectable pesticide (HCH isomers, endosulfan isomers, DDT and its metabolites as well as metoxychlor) residues were present in fish samples. However, all these compounds were below the limit of quantification (LOQ). The other examined pesticide residues were below the limit of detection (LOD). Therefore, the levels of contamination were - in all cases - below the default Maximum Residue Levels (MRLs), established by Regulation (EC) No 396/2005 of the European Parliament and of the Council. The monitoring of pesticide residues content in fish is required to minimize potential adverse effects on the environment and human exposure to these contaminants.

Keywords: contaminants, fish, pesticides residues, QuEChERS method

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Authors: I. Yordanova, H. Kolev, S. Todorova, Z. Cherkezova-Zheleva

Abstract:

Catalysis plays a key role in solving many environmental problems by establishing efficient catalytic systems for environmental protection and reducing emissions of greenhouse gases from industry. Volatile organic compounds are major air pollutants. There are several ways to dispose of emissions like - adsorption, condensation, absorption, bio-filtration, thermal, catalytic, plasma and ultraviolet oxidation. The catalytic oxidation has more advantages over other methods. For example - lower energy consumption; the concentration of the organic contaminant may be low or may vary within wide limits. Catalysts for complete oxidation of VOCs can be classified into three categories: noble metal, metal oxides or supported metal oxides and mixture of noble metals and metal oxides. Most of the catalysts for the complete catalytic oxidation are based on Pt, Pd, Rh or a combination thereof. The oxides of the transition metal are one of the alternatives to noble metal catalysts for these reactions. They are less active at low temperatures, but at higher - their activity is similar. The properties of the catalyst depend on the distribution of the active phase, the medium type of the pre-treatment, the interaction between the active phase and the support and the interaction between the active phase and the reaction medium. Supported mono-component Mn and bi-component Mn-Co systems are examined in present study. The samples are prepared using co-precipitation method. SiO2 (Aerosil) is used as a support. The studied samples were precipitated by NH4OH. The synthesized samples were characterized by XRD, XPS, TPR and tested in the catalytic reaction of complete oxidation of n-hexane, propane, methanol, ethanol and propanol.

Keywords: catalytic oxidation, Co-Mn oxide, oxidation of hydrocarbons and alcohols, environmental protection

Procedia PDF Downloads 383

Authors: S. Vasailor, C. Rattanakawin

Abstract:

Electro-winning of copper metal from dilute sulfate solution (13.7 g/L) was performed in a lab electrolytic cell with stainless-steel cathode and lead-alloy anode. The effects of various parameters including cell voltage, electro-winning temperature and time were studied in order to acquire an appropriate current efficiency of copper deposition. The highest efficiency is about 95% obtaining from electro-winning condition of 3V, 55°C and 3,600 s correspondingly. The cathode copper with 95.5% Cu analyzed using atomic absorption spectrometry can be obtained from this single-winning condition. In order to increase the copper grade, solvent extraction should be used to increase the sulfate concentration, say 50 g/L, prior to winning the cathode copper effectively.

Keywords: copper metal, current efficiency, dilute sulfate solution, electro-winning

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Authors: Jutharat Sunprasert, Ekapong Hirunsirisawat, Narongrit Waraporn, Somporn Peansukmanee

Abstract:

Metal Ship and Robotic Car is one of the hands-on activities in the course, the Fundamental of Engineering that can be divided into three parts. The first part, the metal ships, was made by using engineering drawings, physics and mathematics knowledge. The second part is where the students learned how to construct a robotic car and control it using computer programming. In the last part, the students had to combine the workings of these two objects in the final testing. This aim of study was to investigate the effectiveness of hands-on activity by integrating Science, Technology, Engineering and Mathematics (STEM) concepts to develop scientific and engineering skills. The results showed that the majority of students felt this hands-on activity lead to an increased confidence level in the integration of STEM. Moreover, 48% of all students engaged well with the STEM concepts. Students could obtain the knowledge of STEM through hands-on activities with the topics science and mathematics, engineering drawing, engineering workshop and computer programming; most students agree and strongly agree with this learning process. This indicated that the hands-on activity: “Metal Ship and Robotic Car” is a useful tool to integrate each aspect of STEM. Furthermore, hands-on activities positively influence a student’s interest which leads to increased learning achievement and also in developing scientific and engineering skills.

Keywords: hands-on activity, STEM education, computer programming, metal work

Procedia PDF Downloads 460

Authors: R. Eslami-Farsani, S. M. S. Mousavi Bafrouyi

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During past decades, increasing demand of modified Fiber Metal Laminates (FMLs) has stimulated a strong trend towards the development of these structures. FMLs contain several thin layers of metal bonded with composite materials. Characteristics of FMLs such as low specific mass, high bearing strength, impact resistance, corrosion resistance and high fatigue life are attractive. Nowadays, increasing development can be observed to promote the properties of polymer-based composites by nanofillers. By dispersing strong, nanofillers in polymer matrix, modified composites can be developed and tailored to individual applications. On the other hand, the synergic effects of nanoparticles such as graphene and carbon nanotube can significantly improve the mechanical, electrical and thermal properties of nanocomposites. In present paper, the modifying of FMLs by nanofillers and the dispersing of nanoparticles in the polymers matrix are discussed. The evaluations have revealed that this approach is acceptable. Finally, a prospect is presented. This paper will lead to further work on these modified FML species.

Keywords: fiber metal laminate, nanofiller, polymer matrix, property modification

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Authors: Andrey V. Timofeev, Viktor M. Denisov

Abstract:

A robust sequential nonparametric method is proposed for adaptation to background noise parameters for real-time. The distribution of background noise was modelled like to Huber contamination mixture. The method is designed to operate as an adaptation-unit, which is included inside a detection subsystem of an integrated multichannel monitoring system. The proposed method guarantees the given size of a nonasymptotic confidence set for noise parameters. Properties of the suggested method are rigorously proved. The proposed algorithm has been successfully tested in real conditions of a functioning C-OTDR monitoring system, which was designed to monitor railways.

Keywords: guaranteed estimation, multichannel monitoring systems, non-asymptotic confidence set, contamination mixture

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Authors: Jian-Li Shao

Abstract:

Using Molecular Dynamic (MD) simulations, we simulated the microjet from the metal surface under decaying shock loading. The microjetting processes under release melting conditions are presented in detail, and some properties on the microjet mass and velocity are revealed. The phased increase of microjet mass with shock pressure is found. For all cases, the ratio of the maximal jetting velocity to the surface velocity approximately keeps a constant for liquid state. In addition, the temperature of the microjet can be always above the melting point. When introducing slow decaying profiles, the microjet mass begins to increase with the decay rate, which is dominated by the deformation of the bubble during pull-back. When the decay rate becomes fast enough, the microspall occurs as expected, meanwhile, the microjet appears to reduce because of the shock energy reduction.

Keywords: microjetting, shock, metal, molecular dynamics

Procedia PDF Downloads 193

Authors: Y. Hajjam, I. T. Alami, S. M. Udupa, S. Cherkaoui

Abstract:

Faba bean (Vicia faba L.) is an important food legume crop in Morocco. It is mainly used as human food and feed for animals. Faba bean also plays an important role in cereal-based cropping systems, when rotated with cereals it improves soil fertility by fixing N2 in root nodules mediated by Rhizobium. Both faba bean and its biological nitrogen fixation symbiotic bacterium Rhizobium are affected by different stresses such as: salinity, drought, pH, heavy metal, and the uptake of inorganic phosphate compounds. Therefore, the aim of the present study was to evaluate the phenotypic diversity among the faba bean rhizobial isolates and to select the tolerant strains that can fix N2 under environmental constraints for inoculation particularly for affected soils, in order to enhance the productivity of faba bean and to improve soil fertility. Result have shown that 62% of isolates were fast growing with the ability of producing acids compounds , while 38% of isolates are slow growing with production of alkalins. Moreover, 42.5% of these isolates were able to solubilize inorganic phosphate Ca3(PO4)2 and the index of solubilization was ranged from 2.1 to 3.0. The resistance to extreme pH, temperature, water stress heavy metals and antibiotics lead us to classify rhizobial isolates into different clusters. Finally, the authentication test under greenhouse conditions showed that 55% of the rhizobial isolates could induce nodule formation on faba bean (Vicia faba L.) under greenhouse experiment. This phenotypic characterization may contribute to improve legumes and non legumes crops especially in affected soils and also to increase agronomic yield in the dry areas.

Keywords: rhizobia, vicia faba, phenotypic characterization, nodule formation, environmental constraints

Procedia PDF Downloads 245