Search results for: catalyst layer

Authors: Wei-Jing Li, Ren-Xuan Yang, Kui-Hao Chuang, Ming-Yen Wey

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Nowadays, plastic product and utilization are extensive and have greatly improved our life. Yet, plastic wastes are stable and non-biodegradable challenging issues to the environment. Waste-to-energy strategies emerge a promising way for waste management. This work investigated the co-production of hydrogen and carbon nanotubes from the syngas which was from the gasification of polypropylene. A nickel-silica core-shell catalyst was applied for syngas reaction from plastic waste gasification in a fixed-bed reactor. SiO2 were prepared through various synthesis solvents by Stöber process. Ni plays a role as modified SiO2 support, which were synthesized by deposition-precipitation method. Core-shell catalysts have strong interaction between active phase and support, in order to avoid catalyst sintering. Moreover, Fe or Co metal acts as promoter to enhance catalytic activity. The effects of calcined atmosphere, second metal addition, and reaction temperature on hydrogen production and carbon yield were examined. In this study, the catalytic activity and carbon yield results revealed that the Ni/SiO2 catalyst calcined under H2 atmosphere exhibited the best performance. Furthermore, Co promoted Ni/SiO2 catalyst produced 3 times more than Ni/SiO2 on carbon yield at long-term operation. The structure and morphological nature of the calcined and spent catalysts were examined using different characterization techniques including scanning electron microscopy, transmission electron microscopy, X-ray diffraction. In addition, the quality and thermal stability of the nano-carbon materials were also evaluated by Raman spectroscopy and thermogravimetric analysis.

Keywords: plastic wastes, hydrogen, carbon nanotube, core-shell catalysts

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Authors: Chadel Meriem, Bensmaine Souhila, Chadel Asma, Bouchikhi Chaima

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The Methylammonium Lead Iodide CH3NH3PbI3 is used in solar cell as an absorber layer since 2009. The efficiencies of these technologies have increased from 3.8% in 2009 to 29.15% in 2019. So, these technologies Methylammonium Lead Iodide is promising for the development of high-performance photovoltaic applications. Due to the high cost of the experimental of the solar cells, researchers have turned to other methods like numerical simulation. In this work, we evaluate and simulate the performance of a CH₃NH₃PbI₃ lead-based perovskite solar cell when the amount of materials of absorber layer is reduced. We show that the reducing of thickness the absorber layer influent on performance of the solar cell. For this study, the one-dimensional simulation program, SCAPS-1D, is used to investigate and analyze the performance of the perovskite solar cell. After optimization, maximum conversion efficiency was achieved with 300 nm in absorber layer.

Keywords: methylammonium lead Iodide, perovskite solar cell, caracteristic J-V, effeciency

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Authors: Shigeyuki Haruyama, I Made Gatot Karohika, Akinori Sato, Didik Nurhadiyanto, Ken Kaminishi

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Contact width and contact stress are important design parameters for optimizing corrugated metal gasket performance based on elastic and plastic contact stress. In this study, we used a three-layer metal gasket with Al, Cu, Ni as the outer layer, respectively. A finite element method was employed to develop simulation solution. The gasket model was simulated by using two simulation stages which are forming and tightening simulation. The simulation result shows that aluminum with tangent modulus, Ehal = Eal/150 has the highest slope for contact width. The slope of contact width for plastic mode gasket was higher than the elastic mode gasket.

Keywords: contact width, contact stress, layer, metal gasket, corrugated, simulation

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Authors: Swati Bishnoi, D. Haranath, Vinay Gupta

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In this work, we demonstrate that the power conversion efficiency (PCE) of organic solar cells (OSCs) could be improved significantly by using ZnO doped with Aluminum (Al) and Europium (Eu) as cathode buffer layer (CBL). The ZnO:Al,Eu nanoparticle layer has broadband absorption in the ultraviolet (300-400 nm) region. The Al doping contributes to the enhancement in the conductivity whereas Eu doping significantly improves emission in the visible region. Moreover, this emission overlaps with the absorption range of polymer poly [N -9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′- benzothiadiazole)] (PCDTBT) significantly and results in an enhanced absorption by the active layer and hence high photocurrent. An increase in the power conversion efficiency (PCE) of 6.8% has been obtained for ZnO: Al,Eu CBL as compared to 5.9% for pristine ZnO, in the inverted device configuration ITO/CBL/active layer/MoOx/Al. The active layer comprises of a blend of PCDTBT donor and [6-6]-phenyl C71 butyric acid methyl ester (PC71BM) acceptor. In the reference device pristine ZnO has been used as CBL, whereas in the other one ZnO:Al,Eu has been used as CBL. The role of the luminescent CBL layer is to down-shift the UV light into visible range which overlaps with the absorption of PCDTBT polymer, resulting in an energy transfer from ZnO:Al,Eu to PCDTBT polymer and the absorption by active layer is enhanced as revealed by transient spectroscopy. This enhancement resulted in an increase in the short circuit current which contributes in an increased PCE in the device employing ZnO: Al,Eu CBL. Thus, the luminescent ZnO: Al, Eu nanoparticle CBL has great potential in organic solar cells.

Keywords: cathode buffer layer, energy transfer, organic solar cell, power conversion efficiency

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Authors: Smita Mondal, Dinesh Kumar Pandey, Prakash Biswas

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During past two decades, considerable attention has been given to the value addition of biodiesel derived glycerol (~10wt.%) to make the biodiesel industry economically viable. Among the various glycerol value-addition methods, hydrogenolysis of glycerol to 1,2-propanediol is one of the attractive and promising routes. In this study, highly active and selective γ-Al₂O₃ supported bimetallic Cu-Ni catalyst was developed for selective hydrogenolysis of glycerol to 1,2-propanediol in the liquid phase. The catalytic performance was evaluated in a high-pressure autoclave reactor. The formation of mixed oxide indicated the strong interaction of Cu, Ni with the alumina support. Experimental results demonstrated that bimetallic copper-nickel catalyst was more active and selective to 1,2-PDO as compared to monometallic catalysts due to bifunctional behavior. To verify the effect of calcination temperature on the formation of Cu-Ni mixed oxide phase, the calcination temperature of 20wt.% Cu:Ni(1:1)/Al₂O₃ catalyst was varied from 300°C-550°C. The physicochemical properties of the catalysts were characterized by various techniques such as specific surface area (BET), X-ray diffraction study (XRD), temperature programmed reduction (TPR), and temperature programmed desorption (TPD). The BET surface area and pore volume of the catalysts were in the range of 71-78 m²g⁻¹, and 0.12-0.15 cm³g⁻¹, respectively. The peaks at the 2θ range of 43.3°-45.5° and 50.4°-52°, was corresponded to the copper-nickel mixed oxidephase [JCPDS: 78-1602]. The formation of mixed oxide indicated the strong interaction of Cu, Ni with the alumina support. The crystallite size decreased with increasing the calcination temperature up to 450°C. Further, the crystallite size was increased due to agglomeration. Smaller crystallite size of 16.5 nm was obtained for the catalyst calcined at 400°C. Total acidic sites of the catalysts were determined by NH₃-TPD, and the maximum total acidic of 0.609 mmol NH₃ gcat⁻¹ was obtained over the catalyst calcined at 400°C. TPR data suggested the maximum of 75% degree of reduction of catalyst calcined at 400°C among all others. Further, 20wt.%Cu:Ni(1:1)/γ-Al₂O₃ catalyst calcined at 400°C exhibited highest catalytic activity ( > 70%) and 1,2-PDO selectivity ( > 85%) at mild reaction condition due to highest acidity, highest degree of reduction, smallest crystallite size. Further, the modified Power law kinetic model was developed to understand the true kinetic behaviour of hydrogenolysis of glycerol over 20wt.%Cu:Ni(1:1)/γ-Al₂O₃ catalyst. Rate equations obtained from the model was solved by ode23 using MATLAB coupled with Genetic Algorithm. Results demonstrated that the model predicted data were very well fitted with the experimental data. The activation energy of the formation of 1,2-PDO was found to be 45 kJ mol⁻¹.

Keywords: glycerol, 1, 2-PDO, calcination, kinetic

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Authors: E. Kolvari, N. Koukabi, A. Sabet, A. Fakhraee, M. Ramezanpour

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A green and efficient method for oxidation of thiols to the corresponding disulfides is reported using free nano-iron oxide in the H2O2 and methanol as solvent at room tempereture. H2O2 is anoxidant for S-S coupling variety aromatic of thiols to corresponding disulfide in the presence of supported iron oxide as recoverable catalyst. This reaction is clean, fast, mild and easy work-up with no side reaction.

Keywords: thiol, disulfide, free nano-iron oxide, H2O2, oxidation, coupling

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Authors: Nagwa Mourad Abdelazeem, Marwa El-hussieny

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Multicomponent reactions (MCRs), one-pot reactions form products from more than two different starting compounds. (MCRs) are ideal reaction systems leading to high structural diversity and molecular complexity through a single transformation. (MCRs) have a lot of advantage such as higher yield, less waste generation, use of readily available starting materials and high atom. (MCRs) provide a rapid process for efficient synthesis of key structures in discovery of drug on the other hand silica sulfuric acid (SSA) has been used as an efficient heterogeneous catalyst for many organic transformations. (SSA) is low cost, ease of preparation, catalyst recycling, and ease of handling, so in this article we used 2-(thiophen-2-yl)-1H-indole, N-substituted anilines and aldehyde in the presence of silica sulfuric acid (SSA) as a catalyst in water as solvent at room temperature to prepare 3,3'-(phenylmethylene)bis(2-(thiophen-2-yl)-1H-indole) and N-methyl-4-(phenyl(2-(thiophen-2-yl)-1H-indol-3-yl)methyl)aniline derivatives Via one-pot reaction. Compound 2-(thiophen-2-yl)-1H-indole belongs to the ubiquitous class of indoles which enjoy broad synthetic, biological and industrial applications ]. Cancer is considered the first or second most common reason of death all through the world. So the synthesized compounds will be tested as anticancer. We expected the synthesized compounds will give good results comparison to the reference drug.

Keywords: aldehydes, aza-friedel-crafts reaction, indole, multicomponent reaction

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Authors: Ouahiba Bechiri, Mostefa Abbessi

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The color removal from industrial effluents is a major concern in wastewater treatment. The main objective of this work was to study the decolorization of a mixture of Orange G acid (OG) and naphthol blue black dye (NBB) in aqueous solution by hydrogen peroxide using [H1,5Fe1,5P2W12Mo6O61,23H2O] as catalyst. [H1,5Fe1,5P2 W12Mo6O61,23H2O] is a recyclable DAWSON type heteropolyanion. Effects of various experimental parameters of the oxidation reaction of the dye were investigated. The studied parameters were: the initial pH, H2O2 concentration, the catalyst mass and the temperature. The optimum conditions had been determined, and it was found that efficiency of degradation obtained after 15 minutes of reaction was about 100%. The optimal parameters were: initial pH = 3; [H2O2]0 = 0.08 mM; catalyst mass = 0.05g; for a concentration of dyes = 30mg/L.

Keywords: Dawson type heteropolyanion, naphthol blue-black, dye degradation, orange G acid, oxidation, hydrogen peroxide

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Authors: Mohammad Shafiul Alam, Mineo Saito

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Graphene-based materials have attracted much attention because they are candidates for post silicon materials. Since controlling of impurities is necessary to achieve nano device, we study hydrogen impurity in multi-layer graphene. We perform local spin Density approximation (LSDA) in which the plane wave basis set and pseudopotential are used. Previously hydrogen monomer and dimer in graphene is well theoretically studied. However, hydrogen on multilayer graphene is still not clear. By using first-principles electronic structure calculations based on the LSDA within the density functional theory method, we studied hydrogen monomers and dimers in two-layer graphene. We found that the monomers are spin-polarized and have magnetic moment 1 µB. We also found that most stable dimer is much more stable than monomer. In the most stable structures of the dimers in two-layer graphene, the two hydrogen atoms are bonded to the host carbon atoms which are nearest-neighbors. In this case two hydrogen atoms are located on the opposite sides. Whereas, when the two hydrogen atoms are bonded to the same sublattice of the host materials, magnetic moments of 2 µB appear in two-layer graphene. We found that when the two hydrogen atoms are bonded to third-nearest-neighbor carbon atoms, the electronic structure is nonmagnetic. We also studied hydrogen monomers and dimers in three-layer graphene. The result is same as that of two-layer graphene. These results are very important in the field of carbon nanomaterials as it is experimentally difficult to show the magnetic state of those materials.

Keywords: first-principles calculations, LSDA, multi-layer gra-phene, nanomaterials

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Authors: Jin Lin, Shouxiang Lu, Kim Meow Liew

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The requirement for the long-term mission of the submarine and spacecraft has made the removal of CO₂ and trace CO the critical technology to ensure the health and life of the crews. In this work, CuMnCe, a metal oxide catalyst, supporting K₂CO₃ sorbent was prepared by the wet-solid state impregnation method to realize the integrated CO and CO₂ removal, which might also reduce the volume/mass load of the purification units in the limited space. The as-prepared samples with different addition amount of K₂CO₃ were tested using the fixed bed reactor to reveal the CO oxidation and CO₂ absorption behavior. And the regeneration and stability experiments were also conducted. The results showed that the samples realized the catalyst and sorbent integration to capture CO and CO₂ at the same time. The addition amount of the sorbent had a weak influence on the CO oxidation performance. While the addition amount affected the CO₂ sorption efficiency and capacity significantly. Meanwhile, the presence of water vapor could reduce the CO oxidation activity of the samples similarly, whether with K2CO3 sorbent addition or not. Furtherly, regeneration and stability experiment results showed that the samples after 3-5 times regeneration exhibited almost the same performance of CO and CO₂ removal. Summarily, CuMnCe catalyst supporting K₂CO₃ sorbent could be a good attempt to control CO and CO₂ pollutants generated from the daily equipment running and staff breathing in the confined space such as submarine and spacecraft.

Keywords: CO oxidation, CO₂ absorptio, potassium carbonate, CuMnCe metal oxide, confined space

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Authors: Elitsa Kolentsova, Dimitar Dimitrov, Vasko Idakiev, Tatyana Tabakova, Krasimir Ivanov

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Formaldehyde production by selective oxidation of methanol is an important industrial process. The main by-products in the waste gas are CO and dimethyl ether (DME). The idea of this study is to combine the advantages of both Cu-Mn and Cu-Co catalytic systems by obtaining a new mixed Cu-Mn-Co catalyst with high activity and selectivity at the simultaneous oxidation of CO, methanol, and DME. Two basic Cu-Mn samples with high activity were selected for further investigation: (i) manganese-rich Cu-Mn/γ–Al2O3 catalyst with Cu/Mn molar ratio 1:5 and (ii) copper-rich Cu-Mn/γ-Al2O3 catalyst with Cu/Mn molar ratio 2:1. Manganese in these samples was replaced by cobalt in the whole concentration region, and catalytic properties were determined. The results show a general trend of decreasing the activity toward DME oxidation and increasing the activity toward CO and methanol oxidation with the increase of cobalt up to 60% for both groups of catalyst. This general trend, however, contains specific features, depending on the composition of the catalyst and the nature of the oxidized gas. The catalytic activity of the sample with Cu/(Mn+Co) molar ratio of 2:1 is gradually changed with increasing the cobalt content. The activity of the sample with Cu/(Mn+Co) molar ratio of 1: 5 passes through a maximum at 60% manganese replacement by cobalt, probably due to the formation of highly dispersed Co-based spinel structures (Co3O4 and/or MnCo2O4). In conclusion, the present study demonstrates that the Cu-Mn-Co/γ–alumina supported catalysts have enhanced activity toward CO, methanol and DME oxidation. Cu/(Mn+Co) molar ratio 1:5 and Co/Mn molar ratio 1.5 in the active component can ensure successful oxidation of CO, CH3OH and DME. The active component of the mixed Cu-Mn-Co/γ–alumina catalysts consists of at least six compounds - CuO, Co3O4, MnO2, Cu1.5Mn1.5O4, MnCo2O4 and CuCo2O4, depending on the Cu/Mn/Co molar ratio. Chemical composition strongly influences catalytic properties, this effect being quite variable with regards to the different processes.

Keywords: Cu-Mn-Co catalysts, oxidation, carbon oxide, VOCs

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Authors: Hyeonseok Yoo, Kiseok Oh, Jinsub Choi

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Titanium oxide nanotubes have attracted great attention because of its photocatalytic activity and large surface area. For enhancing electrochemical properties, catalysts should be doped into the structure because titanium oxide nanotubes themselves have low electroconductivity and catalytic activity. It has been reported that Ru and Ir doped titanium oxide electrodes exhibit high efficiency and low overpotential in the oxygen evolution reaction (OER) for water splitting. In general, titanium oxide nanotubes with high aspect ratio cannot be easily doped by conventional complex methods. Herein, two types of facile routes, namely single step anodization and potential shock, for Ru doping into high aspect ratio titanium oxide nanotubes are introduced in detail. When single step anodization was carried out, stability of electrodes were increased. However, onset potential was shifted to anodic direction. On the other hand, when high potential shock voltage was applied, a large amount of ruthenium/ruthenium oxides were doped into titanium oxide nanotubes and thick barrier oxide layers were formed simultaneously. Regardless of doping routes, ruthenium/ ruthenium oxides were homogeneously doped into titanium oxide nanotubes. In spite of doping routes, doping in aqueous solution generally led to incorporate high amount of Ru in titanium oxide nanotubes, compared to that in non-aqueous solution. The amounts of doped catalyst were analyzed by X-ray photoelectron spectroscopy (XPS). The optimum condition for water splitting was investigated in terms of the amount of doped Ru and thickness of barrier oxide layer.

Keywords: doping, potential shock, single step anodization, titanium oxide nanotubes

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Authors: Kumaresh Selvakumar, Man Young Kim

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Catalytic combustor substantially reduces emission entailing fuel-air premixing at very low equivalence ratios. The catalytic combustion of natural gas has the potential to become sufficiently active at light off temperature by the convection of heat from the catalyst surface. Only one channel is selected to investigate both the gas and surface reactions in the catalyst bed because of the honeycomb structure of the catalytic combustor. The objective of the present study is to find the methane catalytic combustion behavior inside the catalytic combustor, where the gas phase kinetics is employed by homogeneous methane combustion and surface chemistry is described with the heterogeneous catalysis of the oxidation of methane on a platinum catalyst. The reaction of the premixed mixture in the catalytic regime improves flame stability with complete combustion for lower operating flame temperature. An overview of the flow behavior is presented inside the single channel catalytic combustor including the operation of catalytic combustion with various F/A ratios and premixed inlet temperature.

Keywords: catalytic combustor, equivalence ratios, flame temperature, heterogeneous catalysis, homogeneous combustion

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Authors: Zhan Panpan, Lu Lan, Sun Yong, He Xiongwen, Yan Dong, Gu Ming

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The function of the two spacecraft docking network, the communication and control of a docking target with various spacecrafts is realized in the space lab data management system. In order to solve the problem of the complex data communication mode between the space lab and various spaceships, and the problem of software reuse caused by non-standard protocol, a data management software system supporting rendezvous and docking with various spaceships has been designed. The software system is based on CCSDS Spcecraft Onboard Interface Service(SOIS). It consists of Software Driver Layer, Middleware Layer and Appliaction Layer. The Software Driver Layer hides the various device interfaces using the uniform device driver framework. The Middleware Layer is divided into three lays, including transfer layer, application support layer and system business layer. The communication of space lab plaform bus and the docking bus is realized in transfer layer. Application support layer provides the inter tasks communitaion and the function of unified time management for the software system. The data management software functions are realized in system business layer, which contains telemetry management service, telecontrol management service, flight status management service, rendezvous and docking management service and so on. The Appliaction Layer accomplishes the space lab data management system defined tasks using the standard interface supplied by the Middleware Layer. On the basis of layered architecture, rendezvous and docking tasks and the rendezvous and docking management service are independent in the software system. The rendezvous and docking tasks will be activated and executed according to the different spaceships. In this way, the communication management functions in the independent flight mode, the combination mode of the manned spaceship and the combination mode of the cargo spaceship are achieved separately. The software architecture designed standard appliction interface for the services in each layer. Different requirements of the space lab can be supported by the use of standard services per layer, and the scalability and flexibility of the data management software can be effectively improved. It can also dynamically expand the number and adapt to the protocol of visiting spaceships. The software system has been applied in the data management subsystem of the space lab, and has been verified in the flight of the space lab. The research results of this paper can provide the basis for the design of the data manage system in the future space station.

Keywords: space lab, rendezvous and docking, data management, software system

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Authors: Tony K. Joseph, Balasubramanian Vathilingam, Stephane Morin

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Currently, the refiners around the world are more focused on improving the yield of light olefins (propylene and ethylene) as both of them are very prominent raw materials to produce wide spectrum of polymeric materials such as polyethylene and polypropylene. Henceforth, it is desirable to increase the yield of light olefins via selective cracking of heavy oil fractions. In this study, zeolite grown on SiC was used as the catalyst to do model cracking reaction of n-heptane. The catalytic cracking of n-heptane was performed in a fixed bed reactor (12 mm i.d.) at three different temperatures (425, 450 and 475 °C) and at atmospheric pressure. A carrier gas (N₂) was mixed with n-heptane with ratio of 90:10 (N₂:n-heptane), and the gaseous mixture was introduced into the fixed bed reactor. Various flow rate of reactants was tested to increase the yield of ethylene and propylene. For the comparison purpose, commercial zeolite was also tested in addition to Zeolite on SiC. The products were analyzed using an Agilent gas chromatograph (GC-9860) equipped with flame ionization detector (FID). The GC is connected online with the reactor and all the cracking tests were successfully reproduced. The entire catalytic evaluation results will be presented during the conference.

Keywords: cracking, catalyst, evaluation, ethylene, heptane, propylene

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Authors: S. S. L. Andrade, E. A. Souza, L. C. L. Santos, C. Moraes, A. K. C. L. Lobato

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Biodiesel production using membrane reactor has become increasingly studied, because this process minimizes some of the main problems encountered in the biodiesel purification. The membrane reactor tries to minimize post-treatment steps, resulting in cost savings and enabling the competitiveness of biodiesel produced by homogeneous alkaline catalysis. This is due to the reaction and product separation may occur simultaneously. In order to evaluate the production of biodiesel from soybean oils using a tubular membrane reactor, a factorial experimental design was conducted (2³) to evaluate the influence of following variables: temperature (45 to 60 °C), catalyst concentration (0.5 to 1% by weight) and molar ratio of oil/methanol (1/6 to 1/9). In addition, the parametric sensitivity was evaluated by the analysis of variance and model through the response surface. The results showed a tendency of influence of the variables in the reaction conversion. The significance effect was higher for the catalyst concentration followed by the molar ratio of oil/methanol and finally the temperature. The best result was obtained under the conditions of 1% catalyst (KOH), molar ratio oil/methanol of 1/9 and temperature of 60 °C, resulting in an ester content of 99.07%.

Keywords: biodiesel production, factorial design, membrane reactor, soybean oil

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Authors: Chinsuk Hong

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This paper investigates the characteristics of wall pressure fluctuations in naturally developing boundary layer flows on axisymmetric bodies experimentally. The axisymmetric body has a modified ellipsoidal blunt nose. Flush-mounted microphones are used to measure the wall pressure fluctuations in the boundary layer flow over the body. The measurements are performed in a low noise wind tunnel. It is found that the correlation between the flow regime and the characteristics of the pressure fluctuations is distinct. The process from small fluctuation in laminar flow to large fluctuation in turbulent flow is investigated. Tollmien-Schlichting wave (T-S wave) is found to generate and develop in transition. Because of the T-S wave, the wall pressure fluctuations in the transition region are higher than those in the turbulent boundary layer.

Keywords: wall pressure fluctuation, boundary layer flow, transition, turbulent flow, axisymmetric body, flow noise

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Authors: Zhemi Xu, Dewei Chu, Sean Li

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Well self-assembled pure and Mn-doped SnO2 nanocubes were synthesized by interface thermodynamic method, which is ideal for highly homogeneous large scale thin film deposition on flexible substrates for various electric devices. Mn-doped SnO2 shows very good resistive switching with high On/Off ratio (over 103), endurance and retention characteristics. More important, the resistive state can be tuned by multi-layer fabrication by alternate pure SnO2 and Mn-doped SnO2 nanocube layer, which improved the memory capacity of resistive switching effectively. Thus, such a method provides transparent, multi-level resistive switching for next generation non-volatile memory applications.

Keywords: metal oxides, self-assembly nanoparticles, multi-level resistive switching, multi-layer thin film

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Authors: Shamsul Chowdhury

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The objective of this paper is to present the detailed analysis of the turbulent wave boundary layer produced by progressive finite-amplitude waves theory. Most of the works have done for the mass transport in the turbulent boundary layer assuming the eddy viscosity is not time varying, where the sediment movement is induced by the mean velocity. Near the ocean bottom, the waves produce a thin turbulent boundary layer, where the flow is highly rotational, and shear stress associated with the fluid motion cannot be neglected. The magnitude and the predominant direction of the sediment transport near the bottom are known to be closely related to the flow in the wave induced boundary layer. The magnitude of water particle velocity at the Crest phase differs from the one of the Trough phases due to the non-linearity of the waves, which plays an important role to determine the sediment movement. The non-linearity of the waves become predominant in the surf zone area, where the sediment movement occurs vigorously. Therefore, in order to describe the flow near the bottom and relationship between the flow and the movement of the sediment, the analysis was done using the non-linear boundary layer equation and the finite amplitude wave theory was applied to represent the velocity fields in the turbulent wave boundary layer. At first, the calculation was done for turbulent wave boundary layer by two-dimensional model where throughout the calculation is non-linear. But Stokes second order wave profile is adopted at the upper boundary. The calculated profile was compared with the experimental data. Finally, the calculation is done based on various modes of the velocity and turbulent energy. The mean velocity is found to differ from condition of the relative depth and the roughness. It is also found that due to non-linearity, the absolute value for velocity and turbulent energy as well as Reynolds stress are asymmetric. The mean velocity of the laminar boundary layer is always positive but in the turbulent boundary layer plays a very complicated role.

Keywords: wave boundary, mass transport, mean velocity, shear stress

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Authors: F. A. Rodríguez-Prada, W Gutierrez, I. D. Mikhailov

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We study the spectral properties of one-electron non-uniform crater-shaped quantum dot whose thickness is increased linearly with different slopes in different radial directions between the central hole and the outer border and which is deposited over thin wetting layer in the presence of the external vertically directed magnetic field. We show that in the adiabatic limit, when the crater thickness is much smaller than its lateral dimension, the one-particle wave functions of the electron confined in such structure in the zero magnetic field case can be found exactly in an analytical form and they can be used subsequently as the base functions in framework of the exact diagonalization method to study the effect of the wetting layer and an external magnetic field applied along of the grown axis on energy levels of one-electron non-uniform quantum dot. It is shown that both the structural non-uniformity and the increase of the thickness of the wetting layer provide a quenching of the Aharonov-Bohm oscillations of the lower energy levels.

Keywords: electronic properties, quantum rings, volcano shaped, wetting layer

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Authors: Muhammad Zubair Akbar Qureshi, Abdul Bari Farooq

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The intention of the current study to analyze the significance of nano-layer in incompressible magneto-hydrodynamics (MHD) flow of a Newtonian nano-fluid consisting of carbon nano-materials has been considered through an absorbent channel with moving porous walls. Using applicable similarity transforms, the governing equations are converted into a system of nonlinear ordinary differential equations which are solved by using the 4th-order Runge-Kutta technique together with shooting methodology. The phenomena of nano-layer have also been modeled mathematically. The inspiration behind this segment is to reveal the behavior of involved parameters on velocity and temperature profiles. A detailed table is presented in which the effects of involved parameters on shear stress and heat transfer rate are discussed. Specially presented the impact of the thickness of the nano-layer and radius of the particle on the temperature profile. We observed that due to an increase in the thickness of the nano-layer, the heat transfer rate increases rapidly. The consequences of this research may be advantageous to the applications of biotechnology and industrial motive.

Keywords: carbon nano-tubes, magneto-hydrodynamics, nano-layer, thermal conductivity

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Authors: A. D. Paryuni, R. N. Nataria, R. Wasito

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Layer chickens are a poultry commodity that has an important role in producing eggs and meat to support the availability of animal proteins. The layer chickens still have obstacles to increasing their productivity, especially due to poultry diseases which can result not only in decreased egg production but also morbidity and mortality. To overcome this condition, phyto-therapeutic and/or phyto-preventive approaches which are efficacious, safe and cheap are needed. One of the herbal spices from Indonesia which is greatly possible to be promoted as an herbal medicine is a red onion (Allium cepa). The objective of the present study was to identify and determine the effect of red onion extract (Allium cepa) as anti-infection and immuno-modulator of Bursa fabricius in layer chickens raised in an open house system. Eighteen layer chickens at 17 days of age were divided randomly into three group of six each. Those were layer chickens without red onion extract (Group K I), Group K II gave red onion extract via drinking water and Group K III gave red onion extract peroral for 30 days. Water and feed were given ad libitum. Necropsy was conducted every 10 days by taking two samples of layer chickens/Group. Bursa fabricius was processed histopathologically and stained-routinely with hematoxylin-eosinand was then examined under light microscope. The results of the present study indicated that bursaFabricius in layer chickens in Groups K I, K II, and K III that were necropsied at days 10 and 20 had normal histologic structures. However, Bursa fabricius in Group K I at day 30, had vacuolization with mild to moderate large vacuoles containing homogenous eosinophilic fluid and atrophy of lymphoid follicles. Mild vacuolization in the follicle of Bursa fabricius was seen in layer chickens in Group K II, whereas layer chickens in Group K III had normal histologic structures of Bursa fabricius. It was concluded that apparently, red onion extract (Allium cepa) has herbal preventive effects against the pathological lesions in the Bursa fabricius of layer chickens.

Keywords: Bursa fabricius, disease of poultry, hematoxylin-eosin, layer chickens, red onion extract

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Authors: Ayman Hijazi, Witold Kwapinski, J. J. Leahy

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Finding a sustainable alternative energy to fossil fuel is an urgent need as various environmental challenges in the world arise. Therefore, formic acid (FA) decomposition has been an attractive field that lies at the center of biomass platform, comprising a potential pool of hydrogen energy that stands as a new energy vector. Liquid FA features considerable volumetric energy density of 6.4 MJ/L and a specific energy density of 5.3 MJ/Kg that qualifies it in the prime seat as an energy source for transportation infrastructure. Additionally, the increasing research interest in FA decomposition is driven by the need of in-situ H2 production, which plays a key role in the hydrogenation reactions of biomass into higher value components. It is reported elsewhere in literature that catalytic decomposition of FA is usually performed in poorly designed setup using simple glassware under magnetic stirring, thus demanding further energy investment to retain the used catalyst. it work suggests an approach that integrates designing a novel catalyst featuring magnetic property with a robust setup that minimizes experimental & measurement discrepancies. One of the most prominent active species for dehydrogenation/hydrogenation of biomass compounds is palladium. Accordingly, we investigate the potential of engrafting palladium metal onto functionalized magnetic nanoparticles as a heterogeneous catalyst to favor the production of CO-free H2 gas from FA. Using ordinary magnet to collect the spent catalyst renders core-shell magnetic nanoparticles as the backbone of the process. Catalytic experiments were performed in a jacketed batch reactor equipped with an overhead stirrer under inert medium. Through a novel approach, FA is charged into the reactor via high-pressure positive displacement pump at steady state conditions. The produced gas (H2+CO2) was measured by connecting the gas outlet to a measuring system based on the amount of the displaced water. The novelty of this work lies in designing a very responsive catalyst, pumping consistent amount of FA into a sealed reactor running at steady state mild temperatures, and continuous gas measurement, along with collecting the used catalyst without the need for centrifugation. Catalyst characterization using TEM, XRD, SEM, and CHN elemental analyzer provided us with details of catalyst preparation and facilitated new venues to alter the nanostructure of the catalyst framework. Consequently, the introduction of amine groups has led to appreciable improvements in terms of dispersion of the doped metals and eventually attaining nearly complete conversion (100%) of FA after 7 hours. The relative importance of the process parameters such as temperature (35-85°C), stirring speed (150-450rpm), catalyst loading (50-200mgr.), and Pd doping ratio (0.75-1.80wt.%) on gas yield was assessed by a Taguchi design-of-experiment based model. Experimental results showed that operating at lower temperature range (35-50°C) yielded more gas while the catalyst loading and Pd doping wt.% were found to be the most significant factors with a P-values 0.026 & 0.031, respectively.

Keywords: formic acid decomposition, green catalysis, hydrogen, mesoporous silica, process optimization, nanoparticles

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Authors: Ratnadip Natwarbhai Bhoi

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The objective of this research paper is to study waste tire crumb rubber granules as a partial concrete replacement by the different percentages of facing layer thickness and without facing layer in the production of rubber cement composite paver block. The physical properties of RCCRP compressive strength, flexural strength, abrasion strength density, and water absorption testing by the IS 15658:2006 method. All these physical properties depend upon the ratio of crumb rubber uses. The result showed that the with facing layer at 15 mm, 25 mm, totally rubberized and without facing layer had little effect on compressive strength, flexural strength and abrasion resistance properties. Water absorption is also important for the service life of the product. The crumb rubber paver block also performed quite well in both compressive strength and abrasion resistance. The rubber cement composite rubber paver block is suitable for nonstructural purposes, such as being lightweight and easy installation for the walkway, sidewalks, and playing area applications.

Keywords: rubber cement, crumb rubber, composite, layer

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Authors: Peter Kus, Anna Ostroverkh, Yurii Yakovlev, Yevheniia Lobko, Roman Fiala, Ivan Khalakhan, Vladimir Matolin

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Hydrogen economy is a concept of low-emission society which harvests most of its energy from renewable sources (e.g., wind and solar) and in case of overproduction, electrochemically turns the excess amount into hydrogen, which serves as an energy carrier. Proton exchange membrane water electrolyzers (PEMWE) are the backbone of this concept. By fast-response electricity to hydrogen conversion, the PEMWEs will not only stabilize the electrical grid but also provide high-purity hydrogen for variety of fuel cell powered devices, ranging from consumer electronics to vehicles. Wider commercialization of PEMWE technology is however hindered by high prices of noble metals which are necessary for catalyzing the redox reactions within the cell. Namely, platinum for hydrogen evolution reaction (HER), running on cathode, and iridium for oxygen evolution reaction (OER) on anode. Possible way of how to lower the loading of Pt and Ir is by using conductive high-surface nanostructures as catalyst supports in conjunction with thin-film catalyst deposition. The presented study discusses unconventional technique of membrane electron assembly (MEA) preparation. Noble metal catalysts (Pt and Ir) were magnetron sputtered in very low loadings onto the surface of porous sublayers (located on gas diffusion layer or directly on membrane), forming so to say localized three-phase boundary. Ultrasonically sprayed corrosion resistant TiC-based sublayer was used as a support material on anode, whereas magnetron sputtered nanostructured etched nitrogenated carbon (CNx) served the same role on cathode. By using this configuration, we were able to significantly decrease the amount of noble metals (to thickness of just tens of nanometers), while keeping the performance comparable to that of average state-of-the-art catalysts. Complex characterization of prepared supported catalysts includes in-cell performance and durability tests, electrochemical impedance spectroscopy (EIS) as well as scanning electron microscopy (SEM) imaging and X-ray photoelectron spectroscopy (XPS) analysis. Our research proves that magnetron sputtering is a suitable method for thin-film deposition of electrocatalysts. Tested set-up of thin-film supported anode and cathode catalysts with combined loading of just 120 ug.cm⁻² yields remarkable values of specific current. Described approach of thin-film low-loading catalyst deposition might be relevant when noble metal reduction is the topmost priority.

Keywords: hydrogen economy, low-loading catalyst, magnetron sputtering, proton exchange membrane water electrolyzer

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Authors: A. S. Al-Fatesh, A. A. Ibrahim, A. M. AlSharekh, F. S. Alqahtani, S. O. Kasim, A. H. Fakeeha

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Hydrogen is the expected future fuel since it produces energy without any pollution. It can be used as a fuel directly or through the fuel cell. It is also used in chemical and petrochemical industry as reducing agent or in hydrogenation processes. It is produced by different methods such as reforming of hydrocarbon, electrolytic method and methane decomposition. The objective of the present paper is to study the decomposition of methane reaction at 700°C and 800°C. The catalysts were prepared via impregnation method using 20%Fe and different proportions of combined alumina and silica support using the following ratios [100%, 90%, 80%, and 0% Al₂O₃/SiO₂]. The prepared catalysts were calcined and activated at 600 OC and 500 OC respectively. The reaction was carried out in fixed bed reactor at atmospheric pressure using 0.3g of catalyst and feed gas ratio of 1.5/1 CH₄/N₂ with a total flow rate 25 mL/min. Catalyst characterizations (TPR, TGA, BET, XRD, etc.) have been employed to study the behavior of catalysts before and after the reaction. Moreover, a brief description of the weight loss and the CH₄ conversions versus time on stream relating the different support ratios over 20%Fe/Al₂O₃/SiO₂ catalysts has been added as well. The results of TGA analysis provided higher weights losses for catalysts operated at 700°C than 800°C. For the 90% Al₂O₃/SiO₂, the activity decreases with the time on stream using 800°C reaction temperature from 73.9% initial CH₄ conversion to 46.3% for a period of 300min, whereas the activity for the same catalyst increases from 47.1% to 64.8% when 700°C reaction temperature is employed. Likewise, for 80% Al₂O₃/SiO₂ the trend of activity is similar to that of 90% Al₂O₃/SiO₂ but with a different rate of activity variation. It can be inferred from the activity results that the ratio of Al₂O₃ to SiO₂ is crucial and it is directly proportional with the activity. Whenever the Al/Si ratio decreases the activity declines. Indeed, the CH₄ conversion of 100% SiO₂ support was less than 5%.

Keywords: Al₂O₃, SiO₂, CH₄ decomposition, hydrogen, iron

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Authors: Sang Hoon Lee, Tae Il Lee, Su Jeong Lee, Jae Min Myoung

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In order to manufacture short gap single Si nanowire (NW) field effect transistor (FET) by imprinting and transferring method, we introduce the method using Al2O3 sacrificial layer. The diameters of cylindrical Si NW addressed between Au electrodes by dielectrophoretic (DEP) alignment method are controlled to 106, 128, and 148 nm. After imprinting and transfer process, cylindrical Si NW is embedded in PVP adhesive and dielectric layer. By curing transferred cylindrical Si NW and Au electrodes on PVP-coated p++ Si substrate with 200nm-thick SiO2, 3μm gap Si NW FET fabrication was completed. As the diameter of embedded Si NW increases, the mobility of FET increases from 80.51 to 121.24 cm2/V•s and the threshold voltage moves from –7.17 to –2.44 V because the ratio of surface to volume gets reduced.

Keywords: Al2O3 sacrificial transfer layer, cylindrical silicon nanowires, dielectrophorestic alignment, field effect transistor

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Authors: A. Gopala Krishna, M. Lakshmi Chaitanya, V. Kalyana Manohar

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In the existent analysis, laser micro machining (LMM) of Silicon carbide (SiCp) reinforced Aluminum 7075 Metal Matrix Composite (Al7075/SiCp MMC) was studied. While machining, Because of the intense heat generated, A layer gets formed on the work piece surface which is called recast layer and this layer is detrimental to the surface quality of the component. The recast layer needs to be as small as possible for precise applications. Therefore, The height of recast layer and the depth of groove which are conflicting in nature were considered as the significant manufacturing criteria, Which determines the pursuit of a machining process obtained in LMM of Al7075/10%SiCp composite. The present work formulates the depth of groove and height of recast layer in relation to the machining parameters using the Response Surface Methodology (RSM) and correspondingly, The formulated mathematical models were put to use for optimization. Since the effect of machining parameters on the depth of groove and height of recast layer was contradictory, The problem was explicated as a multi objective optimization problem. Moreover, An evolutionary Non-dominated sorting genetic algorithm (NSGA-II) was employed to optimize the model established by RSM. Subsequently this algorithm was also adapted to achieve the Pareto optimal set of solutions that provide a detailed illustration for making the optimal solutions. Eventually experiments were conducted to affirm the results obtained from RSM and NSGA-II.

Keywords: Laser Micro Machining (LMM), depth of groove, Height of recast layer, Response Surface Methodology (RSM), non-dominated sorting genetic algorithm

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Authors: G. Sivakumar, T. Pratyusha, D. Gupta, W. Shen

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To get ohmic contact between the cathode and organic semiconductor, transport layers are introduced between the active layer and the electrodes. Generally zinc oxide or titanium dioxide are used as electron transport layer. When electron transport layer is doped with lithium, the resultant film exhibited superior electronic properties, which enables faster electron transport. Doping is accomplished by heat treatment of films with Lithium salts. Li-doped films. We fabricated organic solar cell using PTB7(poly(3-hexylthiopene-2,5- diyl):PCBM(phenyl-C61-butyric acid methyl ester) and found that the solar cells prepared using Li doped films had better performance in terms of efficiency when compared to the undoped transport layers.

Keywords: electron transport layer, higher efficiency, lithium doping, ohmic contact

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Authors: Sharmin Sultana, Nicolas Nuns, Pardis Simon, Jean-Marc Giraudon, Jean-Francois Lamonior, Nathalie D. Geyter, Rino Morent

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Environmental issues, especially air pollution, have become a huge concern of environmental legislation as a consequence of growing awareness in our global world. In this regard, control of volatile organic compounds (VOCs) emission has become an important issue due to their potential toxicity, carcinogenicity, and mutagenicity. The research of innovative technologies for VOC abatement is stimulated to accommodate the new stringent standards in terms of VOC emission. One emerging strategy is the coupling of 2 existing complementary technologies, namely here non-thermal plasma (NTP) and heterogeneous catalysis, to get a more efficient process for VOC removal in air. The objective of this current work is to investigate the abatement of trichloroethylene (TCE-highly toxic chlorinated VOC) from moist air (RH=15%) as a function of time by combined use of multi-pin-to-plate negative DC corona/glow discharge with Fe-doped cryptomelanes catalyst downstream i.e. post plasma-catalysis (PPC) process. For catalyst alone case, experiments reveal that, initially, Fe doped cryptomelane (regardless the mode of Fe incorporation by co-precipitation (Fe-K-OMS-2)/ impregnation (Fe/K-OMS-2)) exhibits excellent activity to decompose TCE compared to cryptomelane (K-OMS-2) itself. A maximum obtained value of TCE abatement after 6 min is as follows: Fe-KOMS-2 (73.3%) > Fe/KOMS-2 (48.5) > KOMS-2 (22.6%). However, with prolonged operation time, whatever the catalyst under concern, the abatement of TCE decreases. After 111 min time of exposure, the catalysts can be ranked as follows: Fe/KOMS-2 (11%) < K-OMS-2 (12.3%) < Fe-KOMS-2 (14.5%). Clearly, this phenomenon indicates catalyst deactivation either by chlorination or by blocking the active sites. Remarkably, in PPC configuration (energy density = 60 J/L, catalyst temperature = 150°C), experiments reveal an enhanced performance towards TCE removal regardless the type of catalyst. After 6 min time on stream, the TCE removal efficiency amount as follows: K-OMS-2 (60%) < Fe/K-OMS-2 (79%) < Fe-K-OMS-2 (99.3%). The enhanced performances over Fe-K-OMS-2 catalyst are attributed to its high surface oxygen mobility and structural defects leading to high O₃ decomposition efficiency to give active species able to oxidize the plasma processed hazardous\by-products and the possibly remaining VOC into CO₂. Moreover, both undoped and doped catalysts remain strongly capable to abate TCE with time on stream. The TCE removal efficiencies of the PPC processes with Fe/KOMS-2 and KOMS-2 catalysts are not affected by time on stream indicating an excellent catalyst stability. When using the Fe-K-OMS-2 as catalyst, TCE abatement slightly reduces with time on stream. However, it is noteworthy to stress that still a constant abatement of 83% is observed during at least 30 minutes. These results prove that the combination of NTP with catalysts not only increases the catalytic activity but also allows to avoid, to some extent, the poisoning of catalytic sites resulting in an enhanced catalyst stability. In order to better understand the different surface processes occurring in the course of the total TCE oxidation in PPC experiments, a detailed X-ray Photoelectron Spectroscopy (XPS) and Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) study on the fresh and used catalysts is in progress.

Keywords: Fe doped cryptomelane, non-thermal plasma, plasma-catalysis, stability, trichloroethylene

Procedia PDF Downloads 189