Search results for: manganese metal

Authors: Azeem Ur Rehman, Asma Tayyaba

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This article deals with the promotional effects of CeO2 on PtPd/CeO2-OMC electro catalysts. The synthesized catalysts are characterized using different physico chemical techniques and evaluated in a formic acid oxidation fuel cell. N2 adsorption/desorption analysis shows that CeO2 modification increases the surface area of OMC from 1005 m2/g to 1119 m2/g. SEM, XRD and TEM analysis reveal that the presence of CeO2 enhances the active metal(s) dispersion on the CeO2-OMC surface. The average particle size of the dispersed metal decreases with the increase of Pt/Pd ratio on CeO2-OMC support. Cyclic voltametry measurement of Pd/CeO2-OMC gives 12 % higher anodic current activity with 83 mV negative shift of the peak potential as compared to unmodified Pd/OMC. In bimetallic catalysts, the addition of Pt improves the activity and stability of the catalysts significantly. Among the bimetallic samples, Pd3Pt1/CeO2-OMC displays superior current density (74.6 mA/cm2), which is 28.3 times higher than that of Pt/CeO2-OMC. It also shows higher stability in extended period of runs with least indication of CO poisoning effects.

Keywords: CeO2, ordered mesoporous carbon (OMC), electro catalyst, formic acid fuel cell

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Authors: Jin-Woo Park, Sung-Soo Lee, Nong-Moon Hwang

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The generation of charged nanoparticles in the gas phase during the Chemical Vapor Deposition (CVD) process has been frequently reported with their subsequent deposition into films and nanostructures in many systems such as carbon, silicon and zinc oxide. The microstructure evolution of films and nanostructures is closely related with the size distribution of charged nanoparticles. To confirm the generation of charged nanoparticles during GaN, the generation of GaN charged nanoparticles was examined in an atmospheric pressure CVD process using a Differential Mobility Analyser (DMA) combined with a Faraday Cup Electrometer (FCE). It was confirmed that GaN charged nanoparticles were generated under the condition where GaN nanostructures were synthesized on the bare and Au-coated Si substrates. In addition, the deposition behaviour depends strongly on the charge transfer rate of metal substrates. On the metal substrates of a lower CTR such as Mo, the deposition rate of GaN was much lower than on those of a higher CTR such as Fe. GaN nanowires tend to grow on the substrates of a lower CTR whereas GaN thin films tend to be deposited on the substrates of a higher CTR.

Keywords: chemical vapour deposition, charged cluster model, generation of charged nanoparticles, deposition behaviour, nanostructures, gan, charged transfer rate

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Authors: K.Narasimhulu, Y. Pydi Setty

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The objective of this present study is the optimization of process parameters in biosorption of Ni(II) and Cd(II) ions by Pseudomonas putida using Response Surface Methodology in a Packed bed bioreactor. The experimental data were also tested with theoretical models to find the best fit model. The present paper elucidates RSM as an efficient approach for predictive model building and optimization of Ni(II) and Cd(II) ions using Pseudomonas putida. In packed bed biosorption studies, comparison of the breakthrough curves of Ni(II) and Cd(II) for Agar immobilized and PAA immobilized Pseudomonas putida at optimum conditions of flow rate of 300 mL/h, initial metal ion concentration of 100 mg/L and bed height of 20 cm with weight of biosorbent of 12 g, it was found that the Agar immobilized Pseudomonas putida showed maximum percent biosorption and bed saturation occurred at 20 minutes. Optimization results of Ni(II) and Cd(II) by Pseudomonas putida from the Design Expert software were obtained as bed height of 19.93 cm, initial metal ion concentration of 103.85 mg/L, and flow rate of 310.57 mL/h. The percent biosorption of Ni(II) and Cd(II) is 87.2% and 88.2% respectively. The predicted optimized parameters are in agreement with the experimental results.

Keywords: packed bed bioreactor, response surface mthodology, pseudomonas putida, biosorption, waste water

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Authors: Adane Gebresilassie Hailemariam, Belete Yilma Hirpaye

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The enhanced concentrations of heavy metals, especially in sediments, may indicate human-induced perturbations rather than natural enrichment through geological weathering. Heavy metals are non-biodegradable, persist in the environment, and are concentrated up to the food chain, leading to enhanced levels in the liver and muscle tissues of fishes, aquatic bryophytes, and aquatic biota. Marine organisms, in general fish in particular, accumulate metals to concentrations many times higher than present in water or sediment as they can take up metals in their organs and concentrate at different levels. Thus, metals acquired through the food chain due to pollution are potential chemical hazards, threatening consumers. The Nile tilapia (oreochromic niloticus), catfish (clarius garpinus), and water samples were collected from five sampling sites, namely, inlet-1, inlet-2, center, outlet-1 and outlet-2 of Lake Chamo. The concentration of major and trace metals Na, K, Mg, Ca, Cr, Co, Ni, Mn and Cu in the two fish muscles, gill and liver, was determined using an atomic absorption spectrometer (AAS) and flame photometer (FP). Metal concentrations in the water have also been evaluated within the two consecutive seasons, winter (dry) and spring (wet). The results revealed that the concentration of those metals in Tilapia’s (O. niloticus) muscle, gill, and liver were Na 44.5, 35.1, 28, Mg 2.8, 8.41, 4.61, K 43, 32, 30, Ca 1.5, 6.0, 5.5, Cr 0.91, 1.2, 3.5, Co 3.0, 2.89, 2.62, Ni 0.94, 1.99, 2.2, Mn 1.23, 1.51, 1.6 and Cu 1.1, 1.99, 3.5 mg kg-1 respectively and in catfish’s muscle, gill and liver Na 25, 39, 41.5, Mg 4.8, 2.87, 6, K 29, 38, 40, Ca 2.5, 8.10, 3.0, Cr 0.65, 3.5, 5.0, Co 2.62, 1.86, 1.73, Ni 1.10, 2.3, 3.1, Mn 1.54, 1.57, 1.59 and Cu 1.01, 1.10, 3.70 mg kg-1 respectively. The highest accumulation of Na and K were observed for tilapia muscle and catfish gill, Mg and Ca got higher in tilapia gill and catfish liver, while Co is higher in muscle of the two fish. The Cr, Ni, Mn and Cu levels were higher in the livers of the two fish species. In conculusion, metal toxicity through food chain is the current dangerous issue for human and othe animals. This needs deep focus to promot the health of living animals. The Details of the work are going to be discussed at the conference.

Keywords: bioaccumulation, catfish, essential metals, nile tilapia

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Authors: H. S. Haroyan, V. R. Tadevosyan

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High gain broadband plasmonic slot nano-antenna has been considered. The theory of plasmonic slot nano-antenna (PSNA) has been developed. The analytical model takes into account also the electrical field inside the metal due to imperfectness of metal in optical range, as well as numerical investigation based on FEM method has been realized. It should be mentioned that Yagi-Uda configuration improves directivity in the plane of structure. In contrast, in this paper the possibility of directivity improvement of proposed PSNA in perpendicular plane of structure by using reflection metallic surface placed under the slot in fixed distance has been demonstrated. It is well known that a directivity improvement brings to the antenna gain increasing. This method of diagram improving is also well known from RF antenna design theory. Moreover the improvement of directivity in the perpendicular plane gives more flexibility in such application as improving the light and atom, ion, molecule interactions by using such type of plasmonic slot antenna. By the analogy of dipole type optical antennas the widening of working wavelengths has been realized by using bowtie geometry of slots, which made the antenna broadband.

Keywords: broadband antenna, high gain, slot nano-antenna, plasmonics.

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Authors: Kateřina Jurdová

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Hanging to the trapezoidal sheet by decking hanger is a very widespread solution used in civil engineering to lead the distribution of energy, sanitary, air distribution system etc. under the roof or floor structure. The trapezoidal decking hanger is usually a part of the whole installation system for specific distribution medium. The leading companies offer installation systems for each specific distribution e.g. pipe rings, sprinkler systems, installation channels etc. Every specific part is connected to the base connector which is decking hanger. The own connection has three main components: decking hanger, threaded bar with nuts and web of trapezoidal sheet. The aim of this contribution is determinate the failure mechanism of each component in connection. Load bearing capacity of most components in connection could be calculated by formulas in European codes. This contribution is focused on problematic of bearing resistance of threaded bar in web of trapezoidal sheet. This issue is studied by experimental research and numerical modelling. This contribution presented the initial results of experiment which is compared with numerical model of specimen.

Keywords: decking hanger, concentrated load, connection, load bearing capacity, trapezoidal metal sheet

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Authors: Chukwuemeka Daniel Ezeliora, Chukwuebuka Lawrence Ezeliora

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The research focused on the appraisal of impact strength on mild steel cladding weld metal geometry. Over the years, poor welding has resulted in failures in engineering components, poor material quality, the collapse of welded materials, and failures in material strength. This is as a result of poor selection and combination of welding input process parameters. The application of the Tungsten Inert Gas (TIG) welding method with weld specimen of length 60; width 40, and thickness of 10 was used for the experiment. A butt joint method was prepared for the welding, and tungsten inert gas welding process was used to perform the twenty (20) experimental runs. A response surface methodology was used to model and to analyze the system. For an adequate polynomial approximation, the experimental design was used to collect the data. The key parameters considered in this work are welding current, gas flow rate, welding speed, and voltage. The range of the input process parameters was selected from the literature and the design. The steps followed to achieve the experimental design and results is the use of response surface method (RSM) implemented in central composite design (CCD) to generate the design matrix, to obtain quadratic model, and evaluate the interactions in the factors as well as optimizing the factors and the response. The result expresses that the best impact strength of the mild steel cladding weld metal geometry is 115.419 Joules. However, it was observed that the result of the input factors is; current 180.4 amp, voltage 23.99 volt, welding speed 142.7 mm.s and gas flow rate 10.8 lit/min as the optimum of the input process parameters. The optimal solution gives a guide for optimal impact strength of the weldment when welding with tungsten inert gas (TIG) under study.

Keywords: mild steel, impact strength, response surface, bead geometry, welding

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Authors: Adebola Ajayi, Olakunle M. Makanjuola

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Effect of sprouting period on proximate, functional and mineral properties of malted sorghum flour was evaluated. The study was carried out to determine the proximate, functional and mineral properties of sprouting period on malted sorghum flour produced. The malted sorghum flour was obtained by sorting, weighing, washing, steeping, draining, germination, drying, dry milling, sieving. Malted sorghum flour was evaluated for proximate composition, functional properties and mineral contents. Moisture, protein, fat content, crude fiber, ash contents and carbohydrate of 24 and 48 hours, were in the range of 10.50-11.0, 11.17-11.17, 1.50-4.00, 2.50-1.50, 1.50-1.54 and 73.15-70.79% respectively. Bulk density ranged between 0.64 and 0.59g/ml, water and oil absorption capacities ranged between 139.3 and 150.0 and 217.3 and 222.7g/g respectively. Calcium, Magnesium, Zinc, Iron and Manganese were also range of 12.5, 59.3-60.0, 3.22-3.25, 3.80-3.90 and 3.22-3.25 mg/100g respectively. The results indicate that the germination of red sorghum resulted in the enhancement of the nutritional quality and its functional properties.

Keywords: sprouting, sorghum, malted sorghum flour, cabinet dryer

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Authors: Alma Shehu, Majlinda Vasjari, Sonila Duka, Loreta Vallja, Nevila Broli

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Humans consume drinking water from several sources, including tap water, bottled water, natural springs, filtered tap water, etc. The quality of drinking water is crucial for human survival given the fact that the consumption of contaminated drinking water is related to many diseases and deaths all over the world. This study represents the investigation of the quality and health risks of different types of drinking waters being consumed by the population in Albania, arising from heavy metals content. Investigated water included industrialized water, tap water, and spring water. In total, 20 samples were analyzed for the content of Pb, Cd, Cr, Ni, Cu, Fe, Zn, Al, and Mn. Determination of each metal concentration in selected samples was conducted by atomic absorption spectroscopy method with electrothermal atomization, GFAAS. Water quality was evaluated by comparing the obtained metals concentrations with the recommended maximum limits, according to the European Directive (98/83/EC) and Guidelines for Drinking Water Quality (WHO, 2017). Metal Index (MI) was used to assess the overall water quality due to heavy metals content. Health risk assessment was conducted based on the recommendations of the USEPA (1996), human health risk assessment, via ingestion. Results of this investigation showed that Al, Ni, Fe, and Cu were the metals found in higher concentrations while Cd exhibited the lowest concentration. Among the analyzed metals, Al (one sample) and Ni (in five samples) exceeded the maximum allowed limit. Based on the pollution metal index, it was concluded that the overall quality of Glina bottled water can be considered as toxic to humans, while the quality of bottled water (Trebeshina) was classified as moderately toxic. Values of health risk quotient (HQ) varied between 1x10⁻⁶-1.3x10⁻¹, following the order Ni > Cd > Pb > Cu > Al > Fe > Zn > Mn. All the values were lower than 1, which suggests that the analyzed samples exhibit no health risk for humans.

Keywords: drinking water, health risk assessment, heavy metals, pollution index

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Authors: Hasan Türe, Kader Terzioglu, Evren Tunca

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Contamination of aqueous environment by heavy metal ions is a serious and complex problem, owing to their hazards to human being and ecological systems. The treatment methods utilized for removing metal ions from aqueous solution include membrane separation, ion exchange and chemical precipitation. However, these methods are limited by high operational cost. Recently, biobased beads are considered as promising biosorbent to remove heavy metal ions from water. The aim of present study was to characterize the alginate/perlite composite beads and to investigate the adsorption performance of obtained beads for removing Pb (II) from aqueous solution. Alginate beads were synthesized by ionic gelation methods and different amount of perlite (aljinate:perlite=1, 2, 3, 4, 5 wt./wt.) was incorporated into alginate beads. Samples were characterized by means of X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM). The effects of perlite level, the initial concentration of Pb (II), initial pH value of Pb(II) solution and effect of contact time on the adsorption capacity of beads were investigated by using batch method. XRD analysis indicated that perlite includes silicon or silicon and aluminum bearing crystalline phase. The diffraction pattern of perlite containing beads is similar to that of that perlite powder with reduced intensity. SEM analysis revealed that perlite was embedded into alginate polymer and SEM-EDX (Energy-Dispersive X-ray) showed that composite beads (aljinate:perlite=1) composed of C (41.93 wt.%,), O (43.64 wt.%), Na (10.20 wt.%), Al (0.74 wt.%), Si (2.72 wt.%) ve K (0.77 wt.%). According to TGA analysis, incorporation of perlite into beads significantly improved the thermal stability of the samples. Batch experiment indicated that optimum pH value for Pb (II) adsorption was found at pH=7 with 1 hour contact time. It was also found that the adsorption capacity of beads decreased with increases in perlite concentration. The results implied that alginate/perlite composite beads could be used as promising adsorbents for the removal of Pb (II) from wastewater. Acknowledgement: This study was supported by TUBITAK (Project No: 214Z146).

Keywords: alginate, adsorption, beads, perlite

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Authors: Vladimir Veremey

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The paper describes the design and simulation of dual-polarization antennas that use the resonance and radiating properties of the H₀₀ mode of metal open waveguides. The proposed antennas are formed by two orthogonal slots in a finite conducting ground plane. The slots are backed by metal screens connected to the ground plane forming open waveguides. It has been shown that the antenna designs can be efficiently used in mm-wave bands. The antenna single mode operational bandwidth is higher than 10%. The antenna designs are very simple and low-cost. They allow flush installation and can be efficiently used in various communication and remote sensing devices on fast moving carriers. Mutual coupling between antennas of the proposed design is very low. Thus, multiple antenna structures with proposed antennas can be efficiently employed in multi-band and in multiple-input-multiple-output (MIMO) systems.

Keywords: antenna, antenna arrays, Multiple-Input-Multiple-Output (MIMO), millimeter wave bands, slot antenna, flush installation, directivity, open waveguide, conformal antennas

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Authors: Raymond Puijk, Rachid Rassir, Inger N. Sierevelt, Anneke Spekenbrink-Sporen, Bart G. C. W. Pijls, Rob G. H. H. Nelissen, Peter A. Nolte

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Background: Among uncemented total knee arthroplasty (TKA), a wide variety of metal surface structures (MSS) and coatings exist to enhance implants' biological properties (i.e., bone ingrowth). This study explores the variety of MSS-coating combinations and compares their mid-long-term survivorships with cemented TKAs, by using data from the Dutch Arthroplasty Register. Methods: A total of 235,500 cemented and 11,132 uncemented primary TKAs with a median follow-up of 5.1 years were included. MSS-coating combinations were (1) Porous-uncoated (n=8986), (2) Beaded-hydroxyapatite (HA)(n=1093), (3) Matte-uncoated (n=846), (4) Matte-Titanium-nitride (TiN) (n=207). Five- and 10-year revision-free survival for all-cause revisions, and aseptic loosening of the tibial component, were calculated and compared by using Kaplan-Meier, Log-rank tests, and multivariable Cox proportional hazard regression analyses. Results: Ten-year survival rates with all-cause revisions as an endpoint, were 94.2% for cement, and 94.7%, 96.3%, 92.1%, and 79.0% for porous-uncoated, beaded-HA, matte-uncoated, and Matte-TiN, respectively (p<0.01). Rates for aseptic loosening were 98.8% for cemented, and 98.7%, 99.8%, 97.2%, and 94.9% for the uncemented, respectively (p<0.01).The beaded-HA implants were half the risk for an all-cause revision compared to cemented implants (p<0.01). Matte-uncoated and matte-TiN implants were at more risk of an all-cause revision than cemented implants (p=0.01, p<0.01). Proportions of revisions for aseptic loosening were comparable among most groups. Conclusion: Based on Dutch registry data, four main MSS-coating combinations among uncemented TKAs were found. survivorships for all-cause revisions and aseptic release differed widely between groups. Beaded-HA and porous-uncoated implants had the best survival rates among the uncemented TKAs and were non-inferior to the cemented TKAs.

Keywords: total knee arthroplasty, cement, uncemented, cementless;, metal surface structure, coating

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Authors: S. Zhuiykov, M. Karbalaei Akbari

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Ultra-low-level incorporation of trace impurities and dopants into two-dimensional (2D) semiconductors is a challenging step towards the development of functional electronic instruments based on 2D materials. Herein, the incorporation of sulphur atoms into 2D Ga2O3 surface oxide film of eutectic gallium-indium alloy (EGaIn) is achieved through plasma-enhanced metal-catalyst dissociation of H2S gas on EGaIn substrate. This process led to the growth of GaS crystalline nanodomains inside amorphous 2D Ga2O3 sublayer films. Consequently, 2D lateral heterophase was developed between the amorphous Ga2O3 and crystalline GaS nanodomains. The materials characterization revealed the alteration of photoluminescence (PL) characteristics and change of valence band maximum (VBM) of functionalized 2D films. The comprehensive studies by conductive atomic force microscopy (c-AFM) showed considerable enhancement of conductivity of 2D Ga2O3/GaS materials (300 times improvement) compared with that of 2D Ga2O3 film. This technique has a great potential for the fabrication of 2D metal oxide devices with tuneable electronic characteristics similar to nano junction memristors and transistors.

Keywords: 2D semiconductors, Ga₂O₃, GaS, plasma-induced functionalization

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Authors: Aliro Villacorta, Laura Rubio, Mohamed Alaraby, Montserrat López Mesas, Victor Fuentes-Cebrian, Oscar H. Moriones, Ricard Marcos, Alba Hernández.

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Micro and nano plastics (MNPLs) are emergent environmental pollutants requiring urgent information on their potential risks to human health. One of the problems associated with the evaluation of their undesirable effects is the lack of real samples matching those resulting from the environmental degradation of plastic wastes. To such end, we propose an easy method to obtain polyethylene terephthalate nano plastics from water plastic bottles (PET-NPLs) but, in principle, applicable to any other plastic goods sources. An extensive characterization indicates that the proposed process produces uniform samples of PET-NPLs of around 100 nm, as determined by using a multi-angle and dynamic light scattering methodology. An important point to be highlighted is that to avoid the metal contamination resulting from methods using metal blades/burrs for milling, trituration, or sanding, we propose to use diamond burrs to produce metal-free samples. To visualize the toxicological profile of the produced PET-NPLs, we have evaluated their ability to be internalized by cells, their cytotoxicity, and their ability to induce oxidative stress and induce DNA damage. In this preliminary approach, we have detected their cellular uptake, but without the induction of significant biological effects. Thus, no relevant increases in toxicity, reactive oxygen species (ROS) induction, or DNA damage -as detected with the comet assay- have been observed. The use of real samples, as produced in this study, will generate relevant data in the discussion about the potential health risks associated with MNPLs exposures.

Keywords: nanoplastics, polyethylene terephthalate, physicochemical characterization, cell uptake, cytotoxicity

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Authors: Andrea M. Rivas-Castillo, Marlenne Gómez-Ramirez, Isela Rodríguez-Pozos, Norma G. Rojas-Avelizapa

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Spent catalysts are considered as hazardous residues of major concern, mainly due to the simultaneous presence of several metals in elevated concentrations. Although hydrometallurgical, pyrometallurgical and chelating agent methods are available to remove and recover some metals contained in spent catalysts; these procedures generate potentially hazardous wastes and the emission of harmful gases. Thus, biotechnological treatments are currently gaining importance to avoid the negative impacts of chemical technologies. To this end, diverse microorganisms have been used to assess the removal of metals from spent catalysts, comprising bacteria, archaea and fungi, whose resistance and metal uptake capabilities differ depending on the microorganism tested. Acidophilic sulfur oxidizing bacteria have been used to investigate the biotreatment and extraction of valuable metals from spent catalysts, namely Acidithiobacillus thiooxidans and Acidithiobacillus ferroxidans, as they present the ability to produce leaching agents such as sulfuric acid and sulfur oxidation intermediates. In the present work, the ability of A. thiooxidans DSM 26636 for the bioleaching of metals contained in five different spent catalysts was assessed by growing the culture in modified Starkey mineral medium (with elemental sulfur at 1%, w/v), and 1% (w/v) pulp density of each residue for up to 21 days at 30 °C and 150 rpm. Sulfur-oxidizing activity was periodically evaluated by determining sulfate concentration in the supernatants according to the NMX-k-436-1977 method. The production of sulfuric acid was assessed in the supernatants as well, by a titration procedure using NaOH 0.5 M with bromothymol blue as acid-base indicator, and by measuring pH using a digital potentiometer. On the other hand, Inductively Coupled Plasma - Optical Emission Spectrometry was used to analyze metal removal from the five different spent catalysts by A. thiooxidans DSM 26636. Results obtained show that, as could be expected, sulfuric acid production is directly related to the diminish of pH, and also to highest metal removal efficiencies. It was observed that Al and Fe are recurrently removed from refinery spent catalysts regardless of their origin and previous usage, although these removals may vary from 9.5 ± 2.2 to 439 ± 3.9 mg/kg for Al, and from 7.13 ± 0.31 to 368.4 ± 47.8 mg/kg for Fe, depending on the spent catalyst proven. Besides, bioleaching of metals like Mg, Ni, and Si was also obtained from automotive spent catalysts, which removals were of up to 66 ± 2.2, 6.2±0.07, and 100±2.4, respectively. Hence, the data presented here exhibit the potential of A. thiooxidans DSM 26636 for the simultaneous bioleaching of metals contained in spent catalysts from diverse provenance.

Keywords: bioleaching, metal removal, spent catalysts, Acidithiobacillus thiooxidans

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Authors: Samiul Islam Hazarika, Domngam Boje, Ananta Kumar Atta

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It is well familiar that solvents play a significant role in modern chemistry. Solvents can change the reactivity and physicochemical properties of molecules in a solution. Keeping this in mind, we have designed and synthesized a mono-triazolyl-linked pyrenyl-appended xylofuranose derivative for the detection of metal ions with changing solvent systems. The incorporation of a sugar backbone in the sensor increases the water solubility and biocompatibility. The experimental study revealed that the xylofuranose-based fluorescence probe did not exhibit any specific selectivity towards metal ions in acetonitrile (CH₃CN) solvent. Whereas, we revealed that triazole-linked pyrenyl-appended xylofuranose-based fluorescent sensor would exhibit high selectivity and sensitivity towards Au³⁺ ions in CH₃CN-H₂O (1/1, v/v) system. This observation might be explained by the viscosity and polarity differences of CH₃CN and CH₃CN-H₂O solvent systems. The formation of the sensor-Au³⁺ complex was also established by high-resolution mass spectrometry (HRMS) data of the complex.

Keywords: triazole, furanose, fluorometric, solvent dependent

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Authors: A. Sharma, S. S. Sandhu, A. Shahi, A. Kumar

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The aim of present investigation was to carry out Finite element modeling of distortion in the case of butt weld. 12mm thick AISI 304L plates were butt welded using three different combinations of groove design namely Double U, Double V and Composite. A full simulation of shielded metal arc welding (SMAW) of nonlinear heat transfer is carried out. Aspects like, temperature-dependent thermal properties of AISI stainless steel above liquid phase, the effect of thermal boundary conditions, were included in the model. Since welding heat dissipation characteristics changed due to variable groove design significant changes in the microhardness tensile strength and impact toughness of the joints were observed. The cumulative distortion was found to be least in double V joint followed by the Composite and Double U-joints. All the joints have joint efficiency more than 100%. CVN value of the Double V-groove weld metal was highest. The experimental results and the FEM results were compared and reveal a very good correlation for distortion and weld groove design for a multipass joint with a standard analogy of 83%.

Keywords: AISI 304 L, Butt joint, distortion, FEM, groove design, SMAW

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Authors: I. Belbachir, T. Benabdallah, N. Belhadj

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The present research work describes the synthesis, through a multi-step strategy, as well as the structural characterization of a polydentate organic ligand, namely the bis(4-amino-5-mercapto-1,2,4-triazole-3-yl)butane (BAMT). The bis-triazolic ligand was characterized by different spectroscopic studies, in order to enlighten its coordination mode, in the neutral and deprotonated forms, towards cobalt(II), nickel(II) and copper(II) sulfates, in both solution and solid state. The stoichiometry of the complexes [neutral BAMT-metal] and [deprotonated BAMT-metal] was first established in a solution of DMF with each of the three metallic cations and their complexation constants calculated, allowing us to compare the stability of the various prepared complexes. The various complexes were finally isolated in the solid state and the coordination mode of neutral and deprotonated BAMT explored towards each of the three metallic sulfates. The establishment of some ligand field parameters (Dq, B, β…) by electronic spectroscopy finally allowed to compare the coordination modes of BAMT towards each of the three metals and to highlight the influence of the deprotonation on the complexing properties of the bis-triazolic ligand.

Keywords: 1, 2, 4-triazol, bis-1, 2, 4-triazol, metallic complexes, coordination in solution and solid state

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Authors: Charmaine Lamiel, Van Hoa Nguyen, Jae-Jin Shim

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Supercapacitors are energy storage devices capable of storing more energy than conventional capacitors and have higher power density than batteries. The advantages of this method include the non-use of reducing agents and acidic medium, and no further use of a post-heat treatment unlike the conventional processes, in which calcination is generally employed after obtaining the initial product. Furthermore, it also offers a shorter reaction time at low temperatures and low power requirements, which allows low fabrication and energy cost. In this study, microwave irradiation was used for the facile and rapid synthesis of mesoporous RGO@(Co,Mn)3O4 nanosheets as an electrode material. The as-prepared electrode exhibited a high capacitance of 953 F•g^−1 at 1 A•g^−1 in a 6 M KOH electrolyte solution. Moreover, the electrode exhibited a high energy density of 76.2 Wh•kg^−1 at a power density of 720 W•kg^−1, and a high power density of 7200 W•kg^−1 at an energy density of 38 Wh•kg^−1. The successful methodology was considered to be efficient and cost-effective, thereby providing an active electrode material with very promising electrochemical performance.

Keywords: cobalt-manganese oxide, electrochemical, graphene, microwave synthesis, supercapacitor

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Authors: Boldin Roman, Liliana Analía Diaz

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As the hydrogen economy continues to expand, reducing energy consumption and emissions while stimulating economic growth, the development of efficient and cost-effective hydrogen production technologies is critical. Among various methods, anion exchange membrane (AEM) water electrolysis stands out due to its potential for using non-noble metal catalysts. The exploration and enhancement of non-noble metal catalysts, such as NiFe-type catalysts, are pivotal for the advancement of AEM technology, ensuring its commercial viability and environmental sustainability. NiFe-type catalysts were synthesized through electrodeposition and characterized both electrochemically and physico-chemically. Various supports, including Ni foam and Ni mesh, were used as porous transport layers (PTLs) to evaluate the effective catalyst thickness and the influence of the PTL in a 5 cm² AEM electrolyzer. This methodological approach allows for a detailed assessment of catalyst performance under operational conditions typical of industrial hydrogen production. The study revealed that electrodeposited non-noble multi-metallic catalysts maintain stable performance as anodes in AEM water electrolysis. NiFe-type catalysts demonstrated superior activity, with the NiFeCoP alloy outperforming others by delivering the lowest overpotential and the highest current density. Furthermore, the use of different PTLs showed significant effects on the electrochemical behavior of the catalysts, indicating that PTL selection is crucial for optimizing performance and efficiency in AEM electrolyzers. Conclusion: The research underscores the potential of non-noble metal catalysts in enhancing efficiency and reducing the costs of AEM electrolysers. The findings highlight the importance of catalyst and PTL optimization in developing scalable and economically viable hydrogen production technologies. Continued innovation in this area is essential for supporting the growth of the hydrogen economy and achieving sustainable energy solutions.

Keywords: AEMWE, electrocatalyst, hydrogen production, water electrolysis.

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Authors: C. Bolakis, I. S. Karanasiou, D. Grbovic, G. Karunasiri, N. Uzunoglu

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A new approach for efficient detection of THz radiation in biomedical imaging applications is proposed. A double-layered absorber consisting of a 32 nm thick aluminum (Al) metallic layer, located on a glass medium (SiO2) of 1 mm thickness, was fabricated and used to design a fine-tuned absorber through a theoretical and finite element modeling process. The results indicate that the proposed low-cost, double-layered absorber can be tuned based on the metal layer sheet resistance and the thickness of various glass media taking advantage of the diversity of the absorption of the metal films in the desired THz domain (6 to 10 THz). It was found that the composite absorber could absorb up to 86% (a percentage exceeding the 50%, previously shown to be the highest achievable when using single thin metal layer) and reflect less than 1% of the incident THz power. This approach will enable monitoring of the transmission coefficient (THz transmission ‘’fingerprint’’) of the biosample with high accuracy, while also making the proposed double-layered absorber a good candidate for a microbolometer pixel’s active element. Based on the aforementioned promising results, a more sophisticated and effective double-layered absorber is under development. The glass medium has been substituted by diluted poly-si and the results were twofold: An absorption factor of 96% was reached and high TCR properties acquired. In addition, a generalization of these results and properties over the active frequency spectrum was achieved. Specifically, through the development of a theoretical equation having as input any arbitrary frequency in the IR spectrum (0.3 to 405.4 THz) and as output the appropriate thickness of the poly-si medium, the double-layered absorber retains the ability to absorb the 96% and reflects less than 1% of the incident power. As a result, through that post-optimization process and the spread spectrum frequency adjustment, the microbolometer detector efficiency could be further improved.

Keywords: bio-imaging, fine-tuned absorber, fingerprint, microbolometer

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Authors: Sharon Waichman, Shahaf Froim, Ido Zukerman, Shmuel Barzilai, Shmual Hayun, Avi Raveh

Abstract:

Boron carbide is a ceramic material with superior properties such as high chemical and thermal stability, high hardness and high wear resistance. Moreover, it has a big cross section for neutron absorption and therefore can be employed in nuclear based applications. However, an efficient attachment of boron carbide to a metal such as aluminum can be very challenging, mainly because of the formation of aluminum-carbon bonds that are unstable in humid environment, the affinity of oxygen to the metal and the different thermal expansion coefficients of the two materials that may cause internal stresses and a subsequent failure of the bond. Here, we aimed to achieving a strong and a durable attachment between the boron carbide coating and the aluminum substrate. For this purpose, we applied Ti as a thin intermediate layer that provides a gradual change in the thermal expansion coefficients of the configured layers. This layer is continuous and therefore prevents the formation of aluminum-carbon bonds. Boron carbide coatings with a thickness of 1-5 µm were deposited on the aluminum substrate by pulse-DC magnetron sputtering. Prior to the deposition of the boron carbide layer, the surface was pretreated by energetic ion plasma followed by deposition of the Ti intermediate adhesive layer in a continuous process. The properties of the Ti intermediate layer were adjusted by the bias applied to the substrate. The boron carbide/aluminum bond was evaluated by various methods and complementary techniques, such as SEM/EDS, XRD, XPS, FTIR spectroscopy and Glow Discharge Spectroscopy (GDS), in order to explore the structure, composition and the properties of the layers and to study the adherence mechanism of the boron carbide/aluminum contact. Based on the interfacial bond characteristics, we propose a desirable solution for improved adhesion of boron carbide to aluminum using a highly efficient intermediate adhesive layer.

Keywords: adhesion, boron carbide coatings, ceramic/metal bond, intermediate layer, pulsed-DC magnetron sputtering

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Authors: Rakesh Kumar, Shashi Janeoo, Ankit Dhiman, Siddharth Chopra

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Arynes are versatile reactive intermediates that offer broad opportunities in green organic synthesis. Arynes are potential aryl group surrogates for the transition metal-free environment friendly arylation reactions. Regioselective arylations of quinolines were achieved by the reactions of quinoline N-oxides with aryne intermediates generated in situ from the Kobayashi precursors. Various 2-substituted quinolines provided 3-arylated-2-substituted quinolines under ambient conditions. Acridine N-oxides also reacted well and provided unusual 4-arylacridines. Various fluorine containing 2,3-diarylquinaolines prepared using this approach were evaluated for antibacterial activity and two compounds inhibited the drug-resistant strains of S-aureus with a good selectivity index. Further, the 2,3-diarylquinolines as the potential optoelectronic materials were prepared by the aryne chemistry approach and their optical and electronic properties for such applications are under study. The aryne intermediates provide an effective Green Chemistry tool to achieve versatile arylated heteroarenes for diverse applications.

Keywords: arynes, arylation, quinolines, acridines.

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Authors: Mansouri Ouarda, Adbdennour Cherif, Boukarma Ziad

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Environmental and biological monitoring are used for the evaluation of exposure to industrial chemicals, and provide a tool for assessing workers’ exposure to chemicals. The organs or tissues where the first biological effects can be observed with increasing amounts of lead toxicity. This study aims at evaluating the effect of the metal element-trace; lead, on the sex hormones in male workers, exposed to this metal on the level of the manufacturing plant of lead accumulators. The results indicate a significant reduction of the testosterone concentration in exposed workers compared to the control. However, the rate of LH was strongly increased at the individuals exposed to Pb. A significant difference concerning the rate of FSH, the hormone Prolactin and cortisol was recorded. The indicators of the lead poisoning indicate a very highly significant increase in the value of Pbs which vary between (142-796 µg/L) among which 50% of the workers present a high lead poisoning and the value of PPZ which vary between (43-554µg/L). The biochemical parameters show a significant increase in the rate of the créatinine, the urea and the acid urique. The hepatic results show no significant differentiation in the rate of TGO and TGP between both groups of study. However the rates of the enzyme phosphatase alkaline, triglyceride, and cholesterol a significant difference were registered.

Keywords: hormons, parameters, physilogical, Pbs, PPZ

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Authors: A. M. Benomair, M. O. Tokhi

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This paper presents the investigation on a system model for the stabilization of a Magnetic Levitation System (Maglev’s). The magnetic levitation system is a challenging nonlinear mechatronic system in which an electromagnetic force is required to suspend an object (metal sphere) in air space. The electromagnetic force is very sensitive to the noise which can create acceleration forces on the metal sphere, causing the sphere to move into the unbalanced region. Maglev’s give the contribution in industry and this system has reduce the power consumption, has increase the power efficiency and reduce the cost maintenance. The common applications for Maglev’s Power Generation (e.g. wind turbine), Maglev’s trains and Medical Device (e.g. Magnetically suspended Artificial Heart Pump). This paper presents the comparison between dynamic response and robust characteristic for both conventional PD and Fuzzy PD controller. The main contribution of this paper is the proof of fuzzy PD type stabilization and robustness. By use of a method to tune the scaling factors of the linear PD type fuzzy controller from an equivalent tuned conventional PD.

Keywords: magnetic levitation system, PD controller, Fuzzy Logic Control, Fuzzy PD

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Authors: Ye Ling, Jiang Yuting, Ruan Haihui

Abstract:

Zinc ion capacitors (ZICs) have garnered tremendous interest recently from researchers due to the perfect integration of batteries and supercapacitors (SC). However, ZICs are currently still facing two major challenges, one is low specific capacitance because of the limited capacity of capacitive cathode materials. In this work, TiN/CNC composites were obtained by a creative method composed of simple mixing and calcination treatment of tetrabutyl titanate (TBOT) and ZIF-8. The formed TiN particles are of ultra-small size and distributed uniformly on the nanoporous carbon matrix, which enhances the conductivity of the composites and the micropores caused by the evaporation of zinc during the calcination process and can serve as the reservoir of electrolytes; both are beneficial to zinc ion storage. When it was used as a cathode with zinc metal and 2M ZnSO₄ as the anode and electrolyte, respectively, in a ZIC device, the assembled device delivered a maximum energy density as high as 153 Wh kg-¹ at a power density of 269.4 W kg-¹, which is superior to many ZICs as reported. Also, it can maintain an energy density of 83.7 Wh kg-¹ at a peak power density of 8.6 kW kg-¹, exhibiting good rate performance. Moreover, when it was charged/discharged for 5000 cycles at a current density of 5 A g-¹, it remained at 85.8% of the initial capacity with a Coulombic efficiency (CE) of nearly 100%.

Keywords: zinc ion capacitor, metal nitride, zif-8, supercapacitor

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Authors: Abdulmajeed Dabwan, Saqib Anwar, Ali Al-Samhan

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Electron Beam Melting (EBM) is a metal powder bed-based Additive Manufacturing (AM) technology, which uses computer-controlled electron beams to create fully dense three-dimensional near-net-shaped parts from metal powder. It gives the ability to produce any complex parts directly from a computer-aided design (CAD) model without tools and dies, and with a variety of materials. However, the quality of the surface finish in EBM process has limitations to meeting the performance requirements of additively manufactured components. The aim of this study is to investigate the cutting forces induced during milling Ti6Al4V produced by EBM as well as the surface quality of the milled surfaces. The effects of cutting speed and radial depth of cut on the cutting forces, surface roughness, and surface morphology were investigated. The results indicated that the cutting speed was found to be proportional to the resultant cutting force at any cutting conditions while the surface roughness improved significantly with the increase in cutting speed and radial depth of cut.

Keywords: electron beam melting, additive manufacturing, Ti6Al4V, surface morphology

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Authors: Sefa Aksu, Ünal Kızıl

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For this study, a town based soil database created in Gümüşçay District of Biga Town, Çanakkale, Turkey. Crop and livestock production are major activities in the district. Nutrient management is mainly based on commercial fertilizer application ignoring the livestock manure. Within the boundaries of district, 122 soil sampling points determined over the satellite image. Soil samples collected from the determined points with the help of handheld Global Positioning System. Labeled samples were sent to a commercial laboratory to determine 11 soil parameters including salinity, pH, lime, organic matter, nitrogen, phosphorus, potassium, iron, manganese, copper and zinc. Based on the test results soil maps for mentioned parameters were developed using remote sensing, GIS, and geostatistical analysis. In this study we developed a GIS database that will be used for soil nutrient management. Methods were explained and soil maps and their interpretations were summarized in the study.

Keywords: geostatistics, GIS, nutrient management, soil mapping

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Authors: Dauda G., Bila Ha Sani Y. M., Magaji M. G., Musa A. M., Hassan H. S.

Abstract:

Introduction: Globimetula oreophila is a parasitic plant with a known therapeutic value that is widely used in the treatment of various ailments, including malaria, hypertension, cancer, diabetes, epilepsy and as a diuretic agent. Objectives: The present study is aimed at analyzing and documenting the level of trace and toxic metals in the crude ethanol leaf extract of G. oreophila. Methods: After collection and authentication, the leaves were air-dried, mashed into powder, weighed and extracted using aqueous ethanol (70%). The crude extract (0.5g) was digested with HNO₃: HCl (3:1); then heated to 2000C and analyzed for its metal content by atomic absorption spectroscopy (AAS). Results: Fe had the highest concentration (32.73mg/kg), while Pb was not detected. The concentrations of Co, Cu, Ni, Zn and Cd detected were 5.97, 10.8, 8.01 and 0.9mg/kg, respectively. The concentration of Cd, Fe and Ni were above the permissible limit of FAO/WHO. Conclusion: The results also show that the analyzed plant is a beneficial source of appropriate and essential trace metals. However, the leaf of G. oreophila in the present study was probably unsafe for long-term use because of the level of Fe, Ni, and Cd concentration.

Keywords: Globimetula oreophila, minerals, trace element, crude extract

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Authors: Yuksel Akinay, Fatih Hayat

Abstract:

The influence of the alloying element on mechanical properties and micro structures of the Fe-22Mn-0.6C-0,6Si twinning induced plasticity (TWIP) steel were investigated at different temperatures. This composition was fabricated by a vacuum induction melting method. This steel was homogenized at 1200◦C for 8h. After heat treatment it was hot-rolled at 1100◦C to 6 mm thickness. The hot rolled plates were cold rolled to 3 mm and annealed at 700 800 and 900 °C for 60 and 150 minute and then air-cooled. X-ray diffractometry (XRD), optic microscope and field emission scanning electron microscope (FESEM), hardness and tensile tests were used to analyse the relationship between mechanical properties and micro structure after annealing process. The results show that, the excellent mechanical properties were obtained after heat treatment process. The tensile strength of material was decreased and the ductility of material was improved with increasing annealing temperature. Ni element were increased the mechanical resistance of specimens and because of carbide precipitation the hardness of specimen annealed at 700 C is higher than others.

Keywords: high manganese, heat treatment, SEM, XRD, cold-rolling

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