Search results for: single metal atom catalysts

Authors: R. Pilafkan, M. Kaffash Irzarahimi, S. F. Asbaghian Namin

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The biaxial buckling behavior of single-layered graphene sheets (SLGSs) is studied in the present work. To consider the size-effects in the analysis, Eringen’s nonlocal elasticity equations are incorporated into classical plate theory (CLPT). A Generalized Differential Quadrature Method (GDQM) approach is utilized and numerical solutions for the critical buckling loads are obtained. Then, molecular dynamics (MD) simulations are performed for a series of zigzag SLGSs with different side-lengths and with various boundary conditions, the results of which are matched with those obtained by the nonlocal plate model to numerical the appropriate values of nonlocal parameter relevant to each type of boundary conditions.

Keywords: biaxial buckling, single-layered graphene sheets, nonlocal elasticity, molecular dynamics simulation, classical plate theory

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Authors: Arvind Mittal, Rajesh Gupta

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Influence of heat input on the micro structure and mechanical properties of shield metal arc welded of duplex stainless steel UNSNO.S-31803 has been investigated. Three heat input combinations designated as low heat (0.675 KJ/mm), medium heat (0.860 KJ/mm) and high heat (1.094 KJ/mm) and weld joints made using these combinations were subjected to micro structural evaluations and tensile and impact testing so as to analyze the effect of thermal arc energy on the micro structure and mechanical properties of these joints. The result of this investigation shows that the joints made using low heat input exhibited higher tensile strength than those welded with medium and high heat input. Heat affected zone of welded joint made with medium heat input has austenitic ferritic grain structure with some patchy austenite provide high toughness. Significant grain coarsening was observed in the heat affected zone (HAZ) of medium and high heat input welded joints, whereas low heat input welded joint shows the fine grain structure in the heat affected zone with small amount of dendritic formation and equiaxed grain structure where inner zone indicates slowly cooled grains in the direction of heat dissipation. This is the main reason for the observable changes of tensile properties of weld joints welded with different arc energy inputs.

Keywords: microstructure, mechanical properties, shield metal arc welded, duplex stainless steel

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Authors: Fatih Suleyman Taskincan, Ahmet Karaarslan

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In this article, the study and analysis of Single Ended Primary Inductance Converter (SEPIC) are presented for battery charging applications that will be used in military applications. The usage of this kind of converters come from its advantage of non-reverse polarity at outputs. As capacitors charge and discharge through inductance, peak current does not occur on capacitors. Therefore, the efficiency will be high compared to buck-boost converters. In this study, the converter (SEPIC) is designed to be operated with Internal Model Controller (IMC). The traditional controllers like Proportional Integral Controller are not preferred as its linearity behavior. Hence IMC is designed for this converter. This controller is a model-based control and provides more robustness and better set point monitoring. Moreover, it can be used for an unstable process where the conventional controller cannot handle the dynamic operation. Matlab/Simulink environment is used to simulate the converter and its controller, then, the results are shown and discussed.

Keywords: DC/DC converter, single ended primary inductance converter, SEPIC, internal model controller, IMC, switched mode power supply

Procedia PDF Downloads 622

Authors: H. O. Udeh, T. E. Kgatla, A. I. O. Jideani

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The effect of Zn2+, Mg2+, and Ba2+ on Saccharomyces pastorianus during very high gravity fermentation was evaluated in this study at independent and three variable combinations. Wort gravity of 21oP was prepared from barley malt, hops and water, to which the metal ions were supplemented in their combinations and subsequently pitched. After 96 h of fermentation, high wort fermentability (%F)= 29.53 was obtained in wort medium containing 900:4 ppm Mg2+ + Ba2+. Increased ethanol titre 7.3491 %(v/v) and 7.1313 %(v/v) were obtained in media containing 900:4 ppm Mg2+ + Ba2+ and 12:900 ppm Zn2+ + Mg2+. Decrease %F= 22.54 and ethanol titre 6.1757% (v/v) was recorded in wort medium containing 12:4 ppm Zn2+ + Ba2+. In media containing the individual metal ions, increased %F= 27.94 and %F= 26.03 were obtained in media containing 700 ppm Mg2+ and 2 ppm Ba2+, with increased ethanol yield of 7.8844% (v/v) and 7.6245% (v/v) respectively. Least %F of 11.75 and 10.80, and ethanol titre of 4.99 (%v/v) and 4.80 (%v/v) were obtained for 10 ppm Zn2+ and 4 ppm Ba2+ respectively.

Keywords: ethanol yield, fermentability, mineral ions, yeast stress, very high gravity fermentation

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Authors: Narasimhulu Korrapati

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The objective of this present study is to optimize the process parameters for batch biosorption of Cr(VI) and Cu(II) ions by Bacillus subtilis using Response Surface Methodology (RSM). Batch biosorption studies were conducted under optimum pH, temperature, biomass concentration and contact time for the removal of Cr(VI) and Cu(II) ions using Bacillus subtilis. From the studies it is noticed that the maximum biosorption of Cr(VI) and Cu(II) was by Bacillus subtilis at optimum conditions of contact time of 30 minutes, pH of 4.0, biomass concentration of 2.0 mg/mL, the temperature of 32°C in batch biosorption studies. Predicted percent biosorption of the selected heavy metal ions by the design expert software is in agreement with experimental results of percent biosorption. The percent biosorption of Cr(VI) and Cu(II) in batch studies is 80% and 78.4%, respectively.

Keywords: heavy metal ions, response surface methodology, biosorption, wastewater

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Authors: Benny Benyamin Nasution, Rahmat Widia Sembiring, Abdul Rahman Dalimunthe, Nursiah Mustari, Nisfan Bahri, Berta br Ginting, Riadil Akhir Lubis, Rita Tavip Megawati, Indri Dithisari

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The earth coordinate system is an important part of an attempt for earthquake forecasting, such as the one using Single Layer Hierarchical Graph Neuron (SLHGN). However, there are a number of problems that need to be worked out before the coordinate system can be utilized for the forecaster. One example of those is that SLHGN requires that the focused area of an earthquake must be constructed in a grid-like form. In fact, within the current earth coordinate system, the same longitude-difference would produce different distances. This can be observed at the distance on the Equator compared to distance at both poles. To deal with such a problem, a coordinate system has been developed, so that it can be used to support the ongoing earthquake forecasting using SLHGN. Two important issues have been developed in this system: 1) each location is not represented through two-value (longitude and latitude), but only a single value, 2) the conversion of the earth coordinate system to the x-y cartesian system requires no angular formulas, which is therefore fast. The accuracy and the performance have not been measured yet, since earthquake data is difficult to obtain. However, the characteristics of the SLHGN results show a very promising answer.

Keywords: hierarchical graph neuron, multidimensional hierarchical graph neuron, single layer hierarchical graph neuron, natural disaster forecasting, earthquake forecasting, earth coordinate system

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Authors: N. Tugrul, E. Moroydor Derun, E. Cinar, A. S. Kipcak, N. Baran Acarali, S. Piskin

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Fly ash is an important waste, produced in thermal power plants which causes very important environmental pollutions. For this reason the usage and evaluation the fly ash in various areas are very important. Nearly, 15 million tons/year of fly ash is produced in Turkey. In this study, usage of fly ash with diatomite and molasses for heavy metal (Cd) adsorption from wastewater is investigated. The samples of Seyitomer region fly ash were analyzed by X-ray fluorescence (XRF) and Scanning Electron Microscope (SEM) then diatomite (0 and 1% in terms of fly ash, w/w) and molasses (0-0.75 mL) were pelletized under 30 MPa of pressure for the usage of cadmium (Cd) adsorption in wastewater. After the adsorption process, samples of Seyitomer were analyzed using Optical Emission Spectroscopy (ICP-OES). As a result, it is seen that the usage of Seyitomer fly ash is proper for cadmium (Cd) adsorption and an optimum adsorption yield with 52% is found at a compound with Seyitomer fly ash (10 g), diatomite (0.5 g) and molasses (0.75 mL) at 2.5 h of reaction time, pH:4, 20ºC of reaction temperature and 300 rpm of stirring rate.

Keywords: heavy metal, fly ash, molasses, diatomite, adsorption, wastewater

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Authors: Jun Hong Lee

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Background: Many dementia patients complain insomnia and depressive mood, and hypnotics and antidepressants are being prescribed. As prevalence of dementia is increasing, insomnia and depressive mood are becoming more important. Objective: We evaluated insomnia and depression in outpatients of dementia center. Patients and Methods/Material and Methods: We reviewed medical records of the patients who visited outpatients clinic of NHIS Ilsan Hospital Dementia Center during 2016. Results: Total 716 patients are included; Subjective Memory Impairment (SMI) : 143 patients (20%), non-amnestic Mild Cognitive Impairment (MCI): single domain 70 (10%), multiple domain 34 (5%), amnestic MCI: single domain 74 (10%), multiple domain 159 (22%), Early onset Alzheimer´s disease (AD): 9 (1%), AD 121 (17%), Vascular dementia: 62 (9%), Mixed dementia 44 (6%). Hypnotics and antidepressants are prescribed as follows; SMI : hypnotics 14 patients (10%), antidepressants 27 (19%), non-amnestic MCI: single domain hypnotics 9 (13%), antidepressants 12 (17%), multiple domain hypnotics 4 (12%), antidepressants 6 (18%), amnestic MCI: single domain hypnotics 10 (14%), antidepressants 16 (22%), multiple domain hypnotics 22 (14%), antidepressants 24 (15%), Early onset Alzheimer´s disease (AD): hypnotics 1 (11%), antidepressants 2 (22%), AD: hypnotics 10 (8%), antidepressants 36 (30%), Vascular dementia: hypnotics 8 (13%), antidepressants 20 (32%), Mixed dementia: hypnotics 4 (9%), antidepressants 17 (39%). Conclusion: Among the outpatients of Dementia Center, MCI and SMI are majorities, and the number of MCI patients are almost half. Depression is more prevalent in AD, and Vascular dementia than MCI and SMI, and about 22% of patients are being prescribed by antidepressants and 11% by hypnotics.

Keywords: insomnia, depression, dementia, antidepressants, hypnotics

Procedia PDF Downloads 158

Authors: Luciana P. Mazur, Tatiana A. Pozdniakova, Rui A. R. Boaventura, Vitor J. P. Vilar

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The principal mechanism of metal ions sequestration by brown algae involves the formation of complexes between the metal ion and functional groups present on the cell wall of the biological material. To understand the role of functional groups on copper(II) uptake by Ascophyllum nodosum, some functional groups were chemically modified. The esterification of carboxylic groups was carried out by suspending the biomass in a methanol/HCl solution under stirring for 48 h and the blocking of the sulfonic groups was performed by repeating the same procedure for 4 cycles of 48 h. The methylation of amines was conducted by suspending the biomass in a formaldehyde/formic acid solution under shaking for 6 h and the chemical modification of sulfhydryl groups on the biomass surface was achieved using dithiodipyridine for 1 h. Equilibrium sorption studies for Cu2+ using the raw and esterified algae were performed at pH 2.0 and 4.0. The experiments were performed using an initial copper concentration of 300 mg/L and algae dose of 1.0 g/L. After reaching the equilibrium, the metal in solution was quantified by atomic absorption spectrometry. The biological material was analyzed by Fourier Transform Infrared Spectroscopy and Potentiometric Titration techniques for functional groups identification and quantification, respectively. The results using unmodified algae showed that the maximum copper uptake capacity at pH 4.0 and 2.0 was 1.17 and 0.52 mmol/g, respectively. At acidic pH values most carboxyl groups are protonated and copper sorption suffered a significant reduction of 56%. Blocking the carboxylic, sulfonic, amines and sulfhydryl functional groups, copper uptake decreased by 24/26%, 69/81%, 1/23% and 40/27% at pH 2.0/4.0, respectively, when compared to the unmodified biomass. It was possible to conclude that the carboxylic and sulfonic groups are the main functional groups responsible for copper binding (>80%). This result is supported by the fact that the adsorption capacity is directly related to the presence of carboxylic groups of the alginate polymer, and the second most abundant acidic functional group in brown algae is the sulfonic acid of fucoidan that contributes, to a lower extent, to heavy metal binding, particularly at low pH.

Keywords: biosorption, brown marine macroalgae, copper, ion-exchange

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Authors: Adebisi M. Tiamiyu, Adewale F. Adeyemi, Olu-Ayobamikale V. Irewunmi

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Fish consumption has increased in recent years in both developing and advanced countries, owing to increased awareness of its nutritional and therapeutic benefits and its availability and affordability relative to other animal protein sources. Fish and fish products, however, are extremely prone to contamination by a wide range of hazardous organic and inorganic substances. This study assessed the levels of three heavy metals, copper (Cu), iron (Fe), and zinc (Zn), in frozen fish imported into Nigeria and sold in Ondo City for their safety for human consumption as recommended by WHO and FEPA. Three species of frozen fish (Scombrus scombrus, Merluccius merluccius, and Clupea harengus) were purchased, and the wet tissues (gills, muscles, and liver) were digested using a 3:1 mixture of nitric acid (HNO3) and hydrochloric acid (HCL). An atomic absorption spectrophotometer (AAS) was used to detect the amount of metal in the tissues. The levels of heavy metals in different fish species' organs varied. The fish had Zn > Fe > Cu heavy metal concentrations in that order. While the concentration of Cu and Fe in the tissues of all three fish species studied were within the WHO and FEPA prescribed limits for food fish, the concentration of Zn in the muscles of M. merluccius (0.262±0.052), C. harengus harengus (0.327±0.099), and S. scombrus (0.362±0.119) was above the prescribed limit (0.075 ppm) set by FEPA. An excessive amount of zinc in the body can cause nausea, headaches, decreased immunity, and appetite loss.

Keywords: heavy metal, atomic absorption spectrophotometer, fish, agencies

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Authors: Chien Y. Lin, Jung Y. Huang, Leu-Wei Lo

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A growing body of data reveals that the membrane cholesterol molecules can alter the signaling pathways of living cells. However, the understanding about how membrane cholesterol modulates receptor proteins is still lacking. Single-molecule tracking can effectively probe into the microscopic environments and thermal fluctuations of receptor proteins in a living cell. In this study we applies single-molecule optical tracking on ligand-induced dimerization process of EGFRs in the plasma membranes of two cancer cell lines (HeLa and A431) and one normal endothelial cell line (MCF12A). We tracked individual EGFR and dual receptors, diffusing in a correlated manner in the plasma membranes of live cells. We developed an energetic model by integrating the generalized Langevin equation with the Cahn-Hilliard equation to help extracting important information from single-molecule trajectories. From the study, we discovered that ligand-bound EGFRs move from non-raft areas into lipid raft domains. This ligand-induced motion is a common behavior in both cancer and normal cells. By manipulating the total amount of membrane cholesterol with methyl-β-cyclodextrin and the local concentration of membrane cholesterol with nystatin, we further found that the amount of cholesterol can affect the stability of EGFR dimers. The EGFR dimers in the plasma membrane of normal cells are more sensitive to the local concentration changes of cholesterol than EGFR dimers in the cancer cells. Our method successfully captures dynamic interactions of receptors at the single-molecule level and provides insight into the functional architecture of both the diffusing EGFR molecules and their local cellular environment.

Keywords: membrane proteins, single-molecule tracking, Cahn-Hilliard equation, EGFR dimers

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Authors: Paiboon Jeamponk, Tasanee Ponglaa, Patchapon Srisanguan

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The aim of this research paper was based on an examination of sources of water supply and water quality for local consumption, conducted at eco-tourism villages of Suan Luang Sub- District Municipality of Amphawa District, Samut Songkram Province. The study incorporated both questionnaire and field work of water testing as the research tool and method. The sample size of 288 households was based on the population of the district, whereas the selected sample water sources were from 60 households: 30 samples were ground water and another 30 were surface water. Degree of heavy metal contamination in the water including copper, iron, manganese, zinc, cadmium and lead was investigated utilizing the Atomic Absorption- Direct Aspiration method. The findings unveiled that 96.0 percent of household water consumption was based on water supply, while the rest on canal, river and rain water. The household behaviour of consumption revealed that 47.2 percent of people routinely consumed water without boiling or filtering prior to consumption. The investigation of water supply quality found that the degree of heavy metal contamination including metal, lead, iron, copper, manganese and cadmium met the standards of the Department of Health.

Keywords: sources of water supply, water quality, water supply, Thailand

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Authors: M. Gazzah, B. Jaouachi, F. Sakli

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This research focuses on the yarn-to-yarn and metal-to-fabric friction effects on the residual bagging behavior expressed by residual bagging height, volume and recovery of some denim fabrics. The results show, that both residual bagging height and residual bagging volume, which is determined using image analysis method, are significantly affected due to the most influential fabric parameter variations, the weft yarns density and the mean frictional coefficients. After the applied number of fatigue cycles, the findings revealed that the weft yarn rigidity contributes on fabric bagging behavior accurately. Among the tested samples, our results show that the elastic fabrics present a high recovery ability to give low bagging height and volume values.

Keywords: bagging recovery, denim fabric, metal-to-fabric friction, residual bagging height, yarn-to-yarn friction

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Authors: Lotfi Hedi Khezami, Mohamed Ben Rabha, N. Sboui, Mounir Gaidi, B. Bessais

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Metal-nano particle-assisted Chemical Etching is an extraordinary developed wet etching method of producing uniform semiconductor nano structure (nano wires) from patterned metallic film on 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 opto electronic 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 opto electronic properties are presented in this paper.

Keywords: stain etching, porous silicon, silicon nanowires, reflectivity, lifetime, solar cells

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Authors: Safa Boudhaouia, Mohamed Amen Gahbiche, Eliane Giraud, Wacef Ben Salem, Philippe Dal Santo

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Multi-point forming (MPF) and asymmetric incremental forming (ISF) are two flexible processes for sheet metal manufacturing. To take advantages of these two techniques, a hybrid process has been developed: The Multipoint Incremental Forming (MPIF). This process accumulates at once the advantages of each of these last mentioned forming techniques, which makes it a very interesting and particularly an efficient process for single, small, and medium series production. In this paper, an experimental and a numerical investigation of this technique are presented. To highlight the flexibility of this process and its capacity to manufacture standard and complex shapes, several pieces were produced by using MPIF. The forming experiments are performed on a 3-axis CNC machine. Moreover, a numerical model of the MPIF process has been implemented in ABAQUS and the analysis showed a good agreement with experimental results in terms of deformed shape. Furthermore, the use of an elastomeric interpolator allows avoiding classical local defaults like dimples, which are generally caused by the asymmetric contact and also improves the distribution of residual strain. Future works will apply this approach to other alloys used in aeronautic or automotive applications.

Keywords: incremental forming, numerical simulation, MPIF, multipoint forming

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Authors: Negar Mesgara, Laleh Maleknia

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In this paper, electrospun CdTe quantum dot / nylon-6 nanofiber mats were successfully prepared. The nanofiber mats were characterized by FE-SEM, XRD and EDX analyses. The results revealed that fibers in different distinct sizes (nano and subnano scale) were obtained with the electrospinning parameters. The phenomenon of ‘on ‘ and ‘off ‘ luminescence intermittency (blinking) of CdTe QDs in nylon-6 was investigated by single-molecule optical microscopy, and we identified that the intermittencies of single QDs were correlated with the interaction of water molecules absorbed on the QD surface. The ‘off’ times, the interval between adjacent ‘on’ states, remained essentially unaffected with an increase in excitation intensity. In the case of ‘on’ time distribution, power law behavior with an exponential cutoff tail is observed at longer time scales. These observations indicate that the luminescence blinking statistics of water-soluble single CdTe QDs is significantly dependent on the aqueous environment, which is interpreted in terms of passivation of the surface trap states of QDs.

Keywords: electrospinning, CdTe quantum dots, Nylon-6, Nanocomposite

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Authors: Ahmed Fawzy, Khaled Ayad, Gh. M. Koura, W. Reda

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The knee joint complex is one of the most commonly injured areas of the body in athletes. Excessive frontal plane knee excursion is considered a risk factor for multiple knee pathologies such as anterior cruciate ligament and patellofemoral joint injuries, however, little is known about the biomechanical factors that contribute to this loading pattern. Objectives: The purpose of this study was to investigate if there is a relationship between hip abductors isometric strength and the value of FPPA during single leg landing tasks in normal male subjects. Methods: One hundred (male) subjects free from lower extremity injuries for at least six months ago participated in this study. Their mean age was (23.25 ± 2.88) years, mean weight was (74.76 ± 13.54) (Kg), mean height was (174.23 ± 6.56) (Cm). The knee frontal plane projection angle was measured by digital video camera using single leg landing task. Hip abductors isometric strength were assessed by portable hand-held dynamometer. Muscle strength had been normalized to the body weight to obtain more accurate measurements. Results: The results demonstrated that there was no significant relationship between hip abductors isometric strength and the value of FPPA during single leg landing tasks in normal male subjects. Conclusion: It can be concluded that there is no relationship between hip abductors isometric strength and the value of FPPA during functional activities in normal male subjects.

Keywords: 2-dimensional motion analysis, hip strength, kinematics, knee injuries

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Authors: Juiwen Liang, Choliang Chung

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In this study, the silicon-base oxide nanofibers with hollow structure were prepared using single-nozzle electrospinning and heat treatment. Firstly, precursor solution was prepared: the Polyvinylpyrrolidone (PVP) and Tetraethyl orthosilicate (TEOS) dissolved in ethanol and to make sure the concentration of solution in appropriate using single-nozzle electrospinning to produce the nanofibers. Secondly, control morphology of the electrostatic spinning nanofibers was conducted, and design the temperature profile to created hollow nanofibers, exploring the morphology and properties of nanofibers. The characterized of nanofibers, following instruments were used: Atomic force microscopy (AFM), Field Emission Scanning Electron Microscope (FE-SEM), Transmission electron microscopy (TEM), Photoluminescence (PL), X-ray Diffraction (XRD). The AFM was used to scan the nanofibers, and 3D Graphics were applied to explore the surface morphology of fibers. FE-SEM and TEM were used to explore the morphology and diameter of nanofibers and hollow nanofiber. The excitation and emission spectra explored by PL. Finally, XRD was used for identified crystallization of ceramic nanofibers. Using electrospinning technique followed by subsequent heat treatment, we have successfully prepared silicon-base oxide nanofibers with hollow structure. Thus, the microstructure and morphology of electrostatic spinning silicon-base oxide hollow nanofibers were explored. Major characteristics of the nanofiber in terms of crystalline, optical properties and crystal structure were identified.

Keywords: electrospinning, single-nozzle, hollow, nanofibers

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Authors: Christian Lauter, Corin Reuter, Shuang Wu, Thomas Troester

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Lightweight construction became more and more important over the last decades in several applications, e.g. in the automotive or aircraft sector. This is the result of economic and ecological constraints on the one hand and increasing safety and comfort requirements on the other hand. In the field of lightweight design, different approaches are used due to specific requirements towards the technical systems. The use of endless carbon fiber reinforced plastics (CFRP) offers the largest weight saving potential of sometimes more than 50% compared to conventional metal-constructions. However, there are very limited industrial applications because of the cost-intensive manufacturing of the fibers and production technologies. Other disadvantages of pure CFRP-structures affect the quality control or the damage resistance. One approach to meet these challenges is hybrid materials. This means CFRP and sheet metal are combined on a material level. Therefore, new opportunities for innovative process routes are realizable. Hybrid lightweight design results in lower costs due to an optimized material utilization and the possibility to integrate the structures in already existing production processes of automobile manufacturers. In recent and current research, the advantages of two-layered hybrid materials have been pointed out, i.e. the possibility to realize structures with tailored mechanical properties or to divide the curing cycle of the epoxy resin into two steps. Current research work at the Chair for Automotive Lightweight Design (LiA) at the Paderborn University focusses on production processes for fiber-metal-laminates. The aim of this work is the development and qualification of a large-scale production process for high-performance fiber-metal-laminates (FML) for industrial applications in the automotive or aircraft sector. Therefore, the prepreg-press-technology is used, in which pre-impregnated carbon fibers and sheet metals are formed and cured in a closed, heated mold. The investigations focus e.g. on the realization of short process chains and cycle times, on the reduction of time-consuming manual process steps, and the reduction of material costs. This paper gives an overview over the considerable steps of the production process in the beginning. Afterwards experimental results are discussed. This part concentrates on the influence of different process parameters on the mechanical properties, the laminate quality and the identification of process limits. Concluding the advantages of this technology compared to conventional FML-production-processes and other lightweight design approaches are carried out.

Keywords: composite material, fiber-metal-laminate, lightweight construction, prepreg-press-technology, large-series production

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Authors: Neha Parekh, Divya Ladha, Poonam Wadhwani, Nisha Shah

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Nano scaled materials have attracted tremendous interest as corrosion inhibitor due to their high surface area on the metal surfaces. It is well known that the zinc oxide nanoparticles have higher reactivity towards aqueous acidic solution. This work presents a new method to incorporate zinc oxide nanoparticles with white sesame seeds extract (nano-green inhibitor) for corrosion protection of zinc in acidic medium. The morphology of the zinc oxide nanoparticles was investigated by TEM and DLS. The corrosion inhibition efficiency of the green inhibitor and nano-green inhibitor was determined by Gravimetric and electrochemical impedance spectroscopy (EIS) methods. Gravimetric measurements suggested that nano-green inhibitor is more effective than green inhibitor. Furthermore, with the increasing temperature, inhibition efficiency increases for both the inhibitors. In addition, it was established the Temkin adsorption isotherm fits well with the experimental data for both the inhibitors. The effect of temperature and Temkin adsorption isotherm revealed Chemisorption mechanism occurring in the system. The activation energy (Ea) and other thermodynamic parameters for inhibition process were calculated. The data of EIS showed that the charge transfer controls the corrosion process. The surface morphology of zinc metal (specimen) in absence and presence of green inhibitor and nano-green inhibitor were performed using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) techniques. The outcomes indicated a formation of a protective layer over zinc metal (specimen).

Keywords: corrosion, green inhibitor, nanoparticles, zinc

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Authors: Bahriye Gülgün, Gökhan Balik, Şükrü Dursun, Kübra Yazici

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The main reasons such as economic growth of society increase of the world population and rapid changes of industrialization cause the amount and the types of pollutants to increase over time. Soil pollution is the typical side effect of industrial activities. As a result of industrial activities, there are large amounts of heavy metal emission every year. Heavy metals are one of the highest pollution sources according to the soil pollution aspect. The usage of hyperaccumulator plants to clean heavy metal polluted soils and the selection of plants for phytoremediation gain importance recently. There are limited numbers of researches on the ornamental plant types of phytoremediation thus; researches on this subject are important. This research is prepared based on the ornamental plant types with phytoremediation abilities.

Keywords: phytoremediation, ornamental plants, landscape reclamation, soil reclamation, environmental pollution

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Authors: Alan Luo, Hunter N. B. Moseley

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Many macromolecular structure entries in the Protein Data Bank (PDB) have a range of regional (localized) quality issues, be it derived from x-ray crystallography, Nuclear Magnetic Resonance (NMR) spectroscopy, or other experimental approaches. However, most PDB entries are judged by global quality metrics like R-factor, R-free, and resolution for x-ray crystallography or backbone phi-psi distribution statistics and average restraint violations for NMR. Regional quality is often ignored when PDB entries are re-used for a variety of structurally based analyses. The binding of ligands, especially ligands involved in energy metabolism, is of particular interest in many structurally focused protein studies. Using a regional quality metric that provides chemically interpretable information from electron density maps, a significant number of outliers in regional structural quality was detected across x-ray crystallographic PDB entries for proteins bound to biochemically critical ligands. In this study, a series of analyses was performed to evaluate both specific and general potential factors that could promote these outliers. In particular, these potential factors were the minimum distance to a metal ion, the minimum distance to a crystal contact, and the isotropic atomic b-factor. To evaluate these potential factors, Fisher’s exact tests were performed, using regional quality criteria of outlier (top 1%, 2.5%, 5%, or 10%) versus non-outlier compared to a potential factor metric above versus below a certain outlier cutoff. The results revealed a consistent general effect from region-specific normalized b-factors but no specific effect from metal ion contact distances and only a very weak effect from crystal contact distance as compared to the b-factor results. These findings indicate that no single specific potential factor explains a majority of the outlier ligand-bound regions, implying that human error is likely as important as these other factors. Thus, all factors, including human error, should be considered when regions of low structural quality are detected. Also, the downstream re-use of protein structures for studying ligand-bound conformations should screen the regional quality of the binding sites. Doing so prevents misinterpretation due to the presence of structural uncertainty or flaws in regions of interest.

Keywords: biomacromolecular structure, coenzyme, electron density discrepancy analysis, x-ray crystallography

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Authors: M. Mathuthu, N. N. Gaxela, R. Y. Olobatoke

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A study was carried out to assess the heavy metal and radionuclide concentrations of water from the waste water treatment plant in Mafikeng Local Municipality to evaluate treatment efficiency. Ten water samples were collected from various stages of water treatment which included sewage delivered to the plant, the two treatment stages and the effluent and also the community. The samples were analyzed for heavy metal content using Inductive Coupled Plasma Mass Spectrometer. Gross α/β activity concentration in water samples was evaluated by Liquid Scintillation Counting whereas the concentration of individual radionuclides was measured by gamma spectroscopy. The results showed marked reduction in the levels of heavy metal concentration from 3 µg/L (As)–670 µg/L (Na) in sewage into the plant to 2 µg/L (As)–170 µg/L (Fe) in the effluent. Beta activity was not detected in water samples except in the in-coming sewage, the concentration of which was within reference limits. However, the gross α activity in all the water samples (7.7-8.02 Bq/L) exceeded the 0.1 Bq/L limit set by World Health Organization (WHO). Gamma spectroscopy analysis revealed very high concentrations of 235U and 226Ra in water samples, with the lowest concentrations (9.35 and 5.44 Bq/L respectively) in the in-coming sewage and highest concentrations (73.8 and 47 Bq/L respectively) in the community water suggesting contamination along water processing line. All the values were considerably higher than the limits of South Africa Target Water Quality Range and WHO. However, the estimated total doses of the two radionuclides for the analyzed water samples (10.62 - 45.40 µSv yr-1) were all well below the reference level of the committed effective dose of 100 µSv yr-1 recommended by WHO.

Keywords: gross α/β activity, heavy metals, radionuclides, 235U, 226Ra, water sample

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Authors: Bukunola A.Oguntade, Abdul- Azeez A. Oderinde

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Fishbone is a type of waste generated from food and food processing industries. Fishbone wastes are usually treated as the source of organic matter for the by-production. It is a rich source of hydroxyapatite (HAP). In this study, the adsorption behavior of fishbone was examined in a batch system as an economically viable adsorbent for the removal of Ni⁺² ions from aqueous solution. The powdered fishbone was characterized using Fourier Transform Infrared (FT-IR) spectrophotometer and Scanning Electron microscope (SEM). The study investigated the influence of adsorbent dosage, solution pH, contact time, and initial metal concentration on the removal of Nickel (II) ions at room temperature. The batch kinetics study showed that the optimum adsorption of Ni(II) was 98% at pH 7, metal ion concentration of 30 mg/L. The results obtained from the experimental work showed that fishbone can be used as an adsorbent for the removal of Ni(II) ions from aqueous solution.

Keywords: adsorption, aqueous media, fishbone, kinetic study

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Authors: Alexander Pesin, Denis Pustovoytov, Mikhail Sverdlik

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Materials with ultrafine-grained structure and unique physical and mechanical properties can be obtained by methods of severe plastic deformation, which include processes of asymmetric rolling (AR). Asymmetric rolling is a very effective way to create ultrafine-grained structures of metals and alloys. Since the asymmetric rolling is a continuous process, it has great potential for industrial production of ultrafine-grained structure sheets. Basic principles of asymmetric rolling are described in detail in scientific literature. In this work finite element modeling of asymmetric rolling and metal forming processes in multiroll gauge was performed. Parameters of the processes which allow achieving significant values of shear strain were defined. The results of the study will be useful for the research of the evolution of ultra-fine metal structure in asymmetric rolling.

Keywords: asymmetric rolling, equivalent strain, FEM, multiroll gauge, profile, severe plastic deformation, shear strain, sheet

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Authors: Lucia Rozumová, Ivo Šafařík, Jana Seidlerová, Pavel Kůs

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Biosorption by biological waste materials from agriculture industry could be a cost-effective technique for removing metal ions from wastewater. The performance of new biosorbent systems, consisting of the waste matrixes which were magnetically modified by iron oxide nanoparticles, for the removal of lead ions from an aqueous solution was tested. The use of low-cost and eco-friendly adsorbents has been investigated as an ideal alternative to the current expensive methods. This article deals with the removal of metal ions from aqueous solutions by modified waste products - orange peels, sawdust, peanuts husks, used tea leaves and ground coffee sediment. Magnetically modified waste materials were suspended in methanol and then was added ferrofluid (magnetic iron oxide nanoparticles). This modification process gives the predictions for the formation of the smart materials with new properties. Prepared material was characterized by using scanning electron microscopy, specific surface area and pore size analyzer. Studies were focused on the sorption and desorption properties. The changes of iron content in magnetically modified materials after treatment were observed as well. Adsorption process has been modelled by adsorption isotherms. The results show that magnetically modified materials during the dynamic sorption and desorption are stable at the high adsorbed amount of lead ions. The results of this study indicate that the biological waste materials as sorbent with new properties are highly effective for the treatment of wastewater.

Keywords: biological waste, sorption, metal ions, ferrofluid

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Authors: Saad Mohamed Elsaid, Nabil Anwar, Mahmoud Rushdi

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One of the reasons for the intensive use of pesticides is to protect agricultural crops and orchards from pests or agricultural worms. The period of time that pesticides stay inside the soil is estimated at about (2) to (12) weeks. Perhaps the most important reason that led to groundwater pollution is the easy leakage of these harmful pesticides from the soil into the aquifers. This research aims to find the best ways to use traded activated charcoal with gold nitrate solution; for removing the deadly pesticides from the aqueous solution by adsorption phenomenon. The most used pesticides in Egypt were selected, such as Malathion, Methomyl Abamectin and, Thiamethoxam. Activated charcoal doped with gold ions was prepared by applying chemical and thermal treatments to activated charcoal using gold nitrate solution. Adsorption of studied pesticide onto activated carbon /Au was mainly by chemical adsorption, forming a complex with the gold metal immobilized on activated carbon surfaces. In addition, the gold atom was considered as a catalyst to cracking the pesticide molecule. Gold activated charcoal is a low cost material due to the use of very low concentrations of gold nitrate solution. its notice the great ability of activated charcoal in removing selected pesticides due to the presence of the positive charge of the gold ion, in addition to other active groups such as functional oxygen and lignin cellulose. The presence of pores of different sizes on the surface of activated charcoal is the driving force for the good adsorption efficiency for the removal of the pesticides under study The surface area of the prepared char as well as the active groups, were determined using infrared spectroscopy and scanning electron microscopy. Some factors affecting the ability of activated charcoal were applied in order to reach the highest adsorption capacity of activated charcoal, such as the weight of the charcoal, the concentration of the pesticide solution, the time of the experiment, and the pH. Experiments showed that the maximum limit revealed by the batch adsorption study for the adsorption of selected insecticides was in contact time (80) minutes at pH (7.70). These promising results were confirmed, and by establishing the practical application of the developed system, the effect of various operating factors with equilibrium, kinetic and thermodynamic studies is evident, using the Langmuir application on the effectiveness of the absorbent material with absorption capacities higher than most other adsorbents.

Keywords: waste water, pesticides pollution, adsorption, activated carbon

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Authors: Sushma Yadav, Anil K. Saroha

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Complex industrial effluent generated from chemical industry is contaminated with toxic and hazardous organic compounds and not amenable to direct biological treatment. To effectively remove many toxic organic pollutants has made it evident that new, compact and more efficient systems are needed. Catalytic Wet Air Oxidation (CWAO) is a promising treatment technology for the abatement of organic pollutants in wastewater. A lot of information is available on using CWAO for the treatment of synthetic solution containing single organic pollutant. But the real industrial effluents containing multi-component mixture of organic compounds were less studied. The main objective of this study is to use the CWAO process for converting the organics into compounds more amenable to biological treatment; complete oxidation may be too expensive. Therefore efforts were made in the present study to explore the potential of alumina based Platinum (Pt) catalyst for the treatment of industrial organic raffinate containing toxic constituents like ammoniacal nitrogen, pyridine etc. The catalysts were prepared by incipient wetness impregnation method and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and BET (Brunauer, Emmett, and Teller) surface area. CWAO experiments were performed at atmospheric pressure and (30 °C - 70 °C) temperature conditions and the results were evaluated in terms of COD removal efficiency. The biodegradability test was performed by BOD/COD ratio for checking the toxicity of the industrial wastewater as well as for the treated water. The BOD/COD ratio of treated water was significantly increased and signified that the toxicity of the organics was decreased while the biodegradability was increased, indicating the more amenability towards biological treatment.

Keywords: alumina based pt catalyst, BOD/COD ratio, catalytic wet air oxidation, COD removal efficiency, industrial organic raffinate

Procedia PDF Downloads 296

Authors: Miled Amel, Ben Maad Hatem, Askri Faouzi, Ben Nasrallah Sassi

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Metal hydride water pumping system uses hydrogen as working fluid to pump water for low head and high discharge. The principal operation of this pump is based on the desorption of hydrogen at high pressure and its absorption at low pressure by a metal hydride. This work is devoted to study a concept of the dynamic behavior of a metal hydride pump using unsteady model and LaNi5 as hydriding alloy. This study shows that with MHP, it is possible to pump 340l/kg-cycle of water in 15 000s using 1 Kg of LaNi5 at a desorption temperature of 360 K, a pumping head equal to 5 m and a desorption gear ratio equal to 33. This study reveals also that the error given by the steady model, using LaNi5 is about 2%.A dimensional mathematical model and the governing equations of the pump were presented to predict the coupled heat and mass transfer within the MHP. Then, a numerical simulation is carried out to present the time evolution of the specific water discharge and to test the effect of different parameters (desorption temperature, absorption temperature, desorption gear ratio) on the performance of the water pumping system (specific water discharge, pumping efficiency and pumping time). In addition, a comparison between results obtained with steady and unsteady model is performed with different hydride mass. Finally, a geometric configuration of the reactor is simulated to optimize the pumping time.

Keywords: dynamic behavior, LaNi5, performance of water pumping system, unsteady model

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Authors: T. Wejrzanowski, M. Grybczuk, E. Tymicki, K. J. Kurzydlowski

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In the present study, numerical simulations of heat and mass transfer in Physical Vapor Transport reactor during silicon carbide single crystal growth are addressed. Silicon carbide is a wide bandgap material with unique properties making it highly applicable for high power electronics applications. Because of high manufacturing costs improvements of SiC production process are required. In this study, numerical simulations were used as a tool of process optimization. Computer modeling allows for cost and time effective analysis of processes occurring during SiC single crystal growth and provides essential information needed for improvement of the process. Quantitative relationship between process conditions, such as temperature or pressure, and crystal growth rate and shape of crystallization front have been studied and verified using experimental data. Basing on modeling results, several process improvements were proposed and implemented.

Keywords: Finite Volume Method, semiconductors, Physica Vapor Transport, silicon carbide

Procedia PDF Downloads 495