Search results for: electric-magnetic anisotropic substrate

Authors: Ajay Dwivedi, M. Suresh Kumar, A. N. Vaidya

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The problem of fruit and vegetable waste management is a grave one and with ever increasing need to feed the exponentially growing population, more and more solid waste in the form of fruit and vegetables waste are generated and its management has become one of the key issues in protection of environment. Energy generation from fruit and vegetables waste by dark anaerobic fermentation is a recent an interesting avenue effective management of solid waste as well as for generating free and cheap energy. In the present study 17 vegetables were characterized for their physical as well as chemical properties, these characteristics were used to determine the hydrogen and methane potentials of vegetable from various models, and also lab scale batch experiments were performed to determine their actual hydrogen and methane production capacity. Lab scale batch experiments proved that vegetable waste can be used as effective substrate for bio hydrogen and methane production, however the expected yield of bio hydrogen and methane was much lower than predicted by models, this was due to the fact that other vital experimental parameters such as pH, total solids content, food to microorganism ratio was not optimized.

Keywords: vegetable waste, physico-chemical characteristics, hydrogen, methane

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Authors: Lukas Munster, Pavel Bazant, Ivo Kuritka

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Zinc oxide sub-micro particles and metallic silver nano particles (Ag/ZnO) were deposited on micro crystalline cellulose surface by a fast, simple and environmentally friendly one-pot microwave assisted solvo thermal synthesis in an open vessel system equipped with an external reflux cooler. In order to increase the interaction between the surface of cellulose and the precipitated Ag/ZnO particles, oxidized form of cellulose (cellulose dialdehyde, DAC) prepared by periodate oxidation of micro crystalline cellulose was added to the reaction mixture of Ag/ZnO particle precursors and untreated micro crystalline cellulose. The structure and morphology of prepared hybrid powder materials were analysed by X-ray diffraction (XRD), energy dispersive analysis (EDX), scanning electron microscopy (SEM) and nitrogen absorption method (BET). Microscopic analysis of the prepared materials treated by ultra-sonication showed that Ag/ZnO particles deposited on the cellulose/DAC sample exhibit increased adhesion to the surface of the cellulose substrate which can be explained by the DAC adhesive effect in comparison with the material prepared without DAC addition.

Keywords: microcrystalline cellulose, microwave synthesis, silver nanoparticles, zinc oxide sub-microparticles, cellulose dialdehyde

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Authors: M. Asghar, K. Mahmood, F. Malik, Lu Na, Y-H Xie, Yasin A. Raja, I. Ferguson

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In this paper, we have reported an enhancement in Seebeck coefficient of un-doped zinc oxide (ZnO) grown by molecular beam epitaxy (MBE) on silicon (001) substrate by annealing treatment. The grown ZnO thin films were annealed in oxygen environment at 500°C – 800°C, keeping a step of 100°C for one hour. Room temperature Seebeck measurements showed that Seebeck coefficient and power factor increased from 222 to 510 µV/K and 8.8×10^-6 to 2.6×10^-4 Wm^-1K^-2 as annealing temperature increased from 500°C to 800°C respectively. This is the highest value of Seebeck coefficient ever reported for un-doped MBE grown ZnO according to best of our knowledge. This observation was related with the improvement of crystal structure of grown films with annealing temperature. X-ray diffraction (XRD) results demonstrated that full width half maximum (FWHM) of ZnO (002) plane decreased and crystalline size increased as the annealing temperature increased. Photoluminescence study revealed that the intensity of band edge emission increased and defect emission decreased as annealing temperature increased because the density of oxygen vacancy related donor defects decreased with annealing temperature. This argument was further justified by the Hall measurements which showed a decreasing trend of carrier concentration with annealing temperature.

Keywords: ZnO, MBE, thermoelectric properties, annealing temperature, crystal structure

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Authors: Sweta Iyer, Nemeshwaree Behary, Jinping Guan, Guoqiang Chen, Vincent Nierstrasz

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Flavin mononucleotide widely known as 'FMN' is a biobased resource derived from riboflavin. The isoalloxazine ring present in the FMN molecule attributes the photoluminescence phenomenon, whereas FMN molecule in the presence of bacterial luciferase enzyme and co-factors such as NADH, long chain aldehyde leads to bioluminescence reaction. In this study, the FMN molecule was treated on cellulosic textile using chromojet technique and the photoluminescence property was characterized using spectroscopy technique. Further, the FMN was used as a substrate along with enzymes and co-factors to treat the non-woven textile, and the bioluminescence property was explored using luminometer equipment. The investigation revealed photoluminescence property on cellulosic textile, and the emission peak was observed at a wavelength around 530 nm with an average corrected spectral intensity of 10×106 CPS/Microamps. In addition, the measurement of nonwoven textile using bioluminescence reaction system exhibited light intensity measured in the form of relative light units (RLU). The study enabled to explore the use of FMN as both photoluminescent and bioluminescent textile. Further investigation would require for stability study of the same to provide an eco-efficient approach to obtain luminescent textile.

Keywords: flavin mononucleotide, photoluminescence, bioluminescence, luminescent textile

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Authors: S. Forel, F. Bouanis, L. Catala, I. Florea, V. Huc, F. Fossard, A. Loiseau, C. Cojocaru

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Single wall carbon nanotubes are seen as excellent candidate for application on nanoelectronic devices because of their remarkable electronic and mechanical properties. These unique properties are highly dependent on their chiral structures and the diameter. Therefore, structure controlled growth of SWNTs, especially directly on final device’s substrate surface, are highly desired for the fabrication of SWNT-based electronics. In this work, we present a new approach to control the diameter of SWNTs and eventually their chirality. Because of their potential to control the SWNT’s chirality, bi-metalics nanoparticles are used to prepare alloy nanoclusters with specific structure. The catalyst nanoparticles are pre-formed following a previously described process. Briefly, the oxide surface is first covered with a SAM (self-assembled monolayer) of a pyridine-functionalized silane. Then, bi-metallic (Fe-Ru, Co-Ru and Ni-Ru) complexes are assembled by coordination bonds on the pre-formed organic SAM. The resultant alloy nanoclusters were then used to catalyze SWNTs growth on SiO2/Si substrates via CH4/H2 double hot-filament chemical vapor deposition (d-HFCVD). The microscopy and spectroscopy analysis demonstrate the high quality of SWNTs that were furthermore integrated into high-quality SWNT-FET.

Keywords: nanotube, CVD, device, transistor

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Authors: Mesfin Angaw Tesfay

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L-xylose is an important intermediate in the pharmaceutical industry, playing a key role in the production of various antiviral and anticancer drugs. Despite its significance, L-xylose is a rare and costly sugar with limited availability in nature. In recent years, enzymatic production methods have garnered considerable attention due to their benefits over conventional chemical synthesis. In this research, a dual enzyme cascade system was developed to synthesize L-xylose from an inexpensive substrate, xylitol. The study involved cloning and co-expressing two key genes: the L-fucose isomerase (L-fucI) gene from Escherichia coli K-12 and the xylitol-4-dehydrogenase (xdh) gene from Pantoea ananatis ATCC 43072 in Escherichia coli. The resulting recombinant cells, engineered with the PET28a-xdh/L-fucI vector, were able to effectively convert xylitol to L-xylose. The system showed optimal performance at 40°C and a pH of 10.0. Moreover, Zn²⁺ (7.5 mM) enhanced the catalytic activity by 1.34 times. This approach yielded 52.2 g/L of L-xylose from an initial 80 g/L xylitol concentration, with a 65% conversion efficiency and a productivity rate of 1.86. The study highlights a practical method for producing L-xylose from xylitol through a co-expression system carrying the L-fucI and xdh genes.

Keywords: l-fucose isomerase, xylitol-4-dehydrogenase, l-xylose, xylitol, co-expression

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Authors: Bi Wa, Su-Yeon Kwon, Ik-Joong Kang

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Surface-enhanced Raman Scattering (SERS) as the principle for enhancing Raman scattering by molecules adsorbed on rough metal surfaces or by nanostructures is used to detect the concentration change of γ-Aminobutyric Acid (GABA). GABA is the mainly inhibitory neurotransmitter in the mammalian central nervous system in the human body. It plays such significant role in reducing neuronal excitability throughout the nervous system. In this case, the Mercaptopropionic Acid (MPA) is used to modified chitosan –gold nanoshell, which enhances the absorption between GABA and Chitosan-gold nanoshell. The sulfur end of the MPA is linked to gold which is the surface of the chitosan nanoparticles via the very strong S–Au bond, while a functional group (carboxyl group) attached to GABA. The controlling of particles’ size and the surface morphology are also the important factors during the whole experiment. The particle around 100nm is using to link to MPA, and the range of GABA from 1mM to 30mM was detected by the Raman Scattering to obtain the calibrate curve. In this study, DLS, SEM, FT-IR, UV, SERS were used to analyze the products to obtain the conclusion.

Keywords: chitosan-gold nanoshell, mercaptopropionic acid, γ-aminobutyric acid, surface-enhanced raman scattering

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Authors: Mohsen Sanayei, Jerzy Szpunar, Sami Penttilä

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Exposure of Nickel-based superalloys to high temperature and harsh environment such as Super-Critical Water (SCW) environment leads to the formation of oxide scales composed of multiple and complex phases that are difficult to differentiate with conventional analysis techniques. In this study, we used simultaneous Electron Backscatter Diffraction (EBSD) and Energy Dispersive X-ray Spectroscopy (EDS) to analyze the complex oxide scales formed on several Nickel-based Superalloys exposed to high temperature SCW. Multi-layered structures of Iron, Nickel, Chromium and Molybdenum oxides and spinels were clearly identified using the simultaneous EBSD-EDS analysis technique. Furthermore, the orientation relationship between the oxide scales and the substrate has been investigated.

Keywords: electron backscatter diffraction, energy dispersive x-ray spectroscopy, superalloy, super-critical water

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Authors: Patience Orobosa Olajide

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Five hydrocarbon degrading bacterial strains isolated from contaminated environment were investigated with respect to polyhydroxybutyrate (PHB) biosynthesis. Screening for bioplastic production was done on assay mineral salts agar medium containing 0.2% poly (3-hydroxybutyrate) as the sole carbon source. Two of the test bacteria were positive for PHB biosynthesis and were identified based on gram staining, biochemical tests, 16S rRNA gene sequence analysis as Pseudomonas aeruginosa and Bacillus licheniformis which grew at 37 and up to 65 °C respectively, thus suggesting the later to be thermotolerant. In this study, the effects of different carbon and nitrogen sources on PHB production in these strains were investigated. Maximum PHB production was obtained in 48 hr for the two strains and amounted to yields of 72.86 and 62.22 percentages for Bacillus licheniformis and Pseudomonas aeruginosa respectively. In these strains, glycine was the most efficient carbon sources for the production of PHB compared with other carbon (glucose, lactose, sucrose, Arabinose) and nitrogen (L- glycine, L-cysteine, DL-Tryptophan, and Potassium Nitrate) sources. The screening of microbial strains for industrial PHB production should be based on several factors including the cell’s capability to mineralize an inexpensive substrate, rate of growth and the extent of polymer accumulation.

Keywords: bacteria, poly-3-hydroxybutyrate (PHB), hydrocarbon, thermotolerant

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Authors: Joseph Fitoussi, Mohammadali Shirinbayan, Abbas Tcharkhtchi

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Due to material flow during processing, short fiber reinforced composites structures obtained by injection or compression molding generally present strong spatial microstructure variation. On the other hand, quasi-static, dynamic, and fatigue behavior of these materials are highly dependent on microstructure parameters such as fiber orientation distribution. Indeed, because of complex damage mechanisms, SFRC structures design is a key challenge for safety and reliability. In this paper, we propose a micromechanical model allowing prediction of damage behavior of real structures as a function of microstructure spatial distribution. To this aim, a statistical damage criterion including strain rate and fatigue effect at the local scale is introduced into a Mori and Tanaka model. A critical local damage state is identified, allowing fatigue life prediction. Moreover, the multi-scale model is coupled with an experimental intrinsic link between damage under monotonic loading and fatigue life in order to build an abacus giving Tsai-Wu failure criterion parameters as a function of microstructure and targeted fatigue life. On the other hand, the micromechanical damage model gives access to the evolution of the anisotropic stiffness tensor of SFRC submitted to complex thermomechanical loading, including quasi-static, dynamic, and cyclic loading with temperature and amplitude variations. Then, the latter is used to fill out microstructure dependent material cards in finite element analysis for design optimization in the case of complex loading history. The proposed methodology is illustrated in the case of a real automotive component made of sheet molding compound (PSA 3008 tailgate). The obtained results emphasize how the proposed micromechanical methodology opens a new path for the automotive industry to lighten vehicle bodies and thereby save energy and reduce gas emission.

Keywords: short fiber reinforced composite, structural design, damage, micromechanical modelling, fatigue, strain rate effect

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Authors: Mohammed Berka, Khaled Merit

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Recent works on microwave filters show that the constituent materials such filters are very important in the design and realization. Several solutions have been proposed to improve the qualities of filtering. In this paper, we propose a new dual band-pass filter based on the coupling of a composite (CRLH) coplanar waveguide with complementary split ring resonators (CSRRs). The (CRLH) CPW is composed of two resonators, each one has an interdigital capacitor (CID) and two short-circuited stubs parallel to top ground plane. On the lower ground plane, we use defected ground structure technology (DGS) to engrave two (CSRRs) offered with different shapes and dimensions. Between the top ground plane and the substrate, we place a ferrite layer to control the electromagnetic coupling between (CRLH) CPW and (CSRRs). The global filter that has coplanar access will have a dual band-pass behavior around the magnetic resonances of (CSRRs). Since there’s no scientific or experimental result in the literature for this kind of complicated structure, it was necessary to perform simulation using HFSS Ansoft designer.

Keywords: complementary split ring resonators, coplanar waveguide, ferrite, filter, stub.

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Authors: Priyanka Aggarwal, Priyanka Mangla

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This work has focused on the aspect of UWB antenna design, which is very suitable for portable UWB applications. The design of new UWB antenna faces some challenges. The antenna should be compact, preferably conformal, and low cost for manufacture, and have good electrical performance, such as good matching, directional radiation performance over a wide band, good time response, etc. Keeping these goals in mind a compact and directional compact open-slot antenna was built. The antenna radiating structure is in the form of two exponentially tapered arms that lie on the opposite sides of the substrate. The antenna operates over the frequency band from 2.95 GHz to more than 12.1 GHz. It exhibits a directive radiation performance with a peak gain which is between 5.4 dBi and 8.3 dBi in the specified band. The antenna has linear phase response over the entire UWB frequency range and hence constant group delay which is vital for transmission and reception of sub-nanosecond pulses. Due to its planar profile, physically compact size, wide impedance bandwidth, directive performance over a wide bandwidth proposed antenna is a good candidate for portable UWB applications and other UWB integrated circuits.

Keywords: inset feed patch antenna, ultra wide band, radiation performance, geometry, antenna

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Authors: Shahid-ul-Islam, Faqeer Mohammad

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The present study was conducted to investigate the effect of annatto, teak and flame of the forest natural dyes on color, fastness, and antimicrobial property of protein based textile substrate. The color strength (K/S) of wool samples at various concentrations of dyes were analysed using a Reflective Spectrophotometer. The antimicrobial activity of natural dyes before and after application on wool was tested against common human pathogens Escherichia coli, Staphylococcus aureus, and Candida albicans, by using micro-broth dilution method, disc diffusion assay and growth curve studies. The structural morphology of natural protein fibre (wool) was investigated by Scanning Electron Microscopy (SEM). Annatto and teak natural dyes proved very effective in inhibiting the microbial growth in solution phase and after application on wool and resulted in a broad beautiful spectrum of colors with exceptional fastness properties. The results encourage the search and exploitation of new plant species as source of dyes to replace toxic synthetic antimicrobial agents currently used in textile industry.

Keywords: annatto, antimicrobial agents, natural dyes, green textiles

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Authors: Yadollah Hezarjaribi, Mahdie Yari Esboi

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In this paper, a novel MEMS capacitive pressure sensor with small size and high sensitivity is presented. This sensor has the separated clamped square diaphragm and the movable plate. The diaphragm material is polysilicon. The movable and fixed plates and mechanical coupling are gold. The substrate and diaphragm are pyrex glass and polysilicon, respectively. In capacitive sensor the sensitivity is proportional to deflection and capacitance changes with pressure for this reason with this design is improved the capacitance and sensitivity with small size. This sensor is designed for low pressure between 0-60 mmHg that is used for medical application such as treatment of an incurable disease called glaucoma. The size of this sensor is 350×350 µm2 and the thickness of the diaphragm is 2µm with 1μ air gap. This structure is designed by intellisuite software. In this MEMS capacitive pressure sensor the sensor sensitivity, diaphragm mechanical sensitivity for polysilicon diaphragm are 0.0469Pf/mmHg, 0.011 μm/mmHg, respectively. According to the simulating results for low pressure, the structure with polysilicon diaphragm has more change of the displacement and capacitance, this leads to high sensitivity than other diaphragms.

Keywords: glaucoma, MEMS capacitive pressure sensor, square clamped diaphragm, polysilicon

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Authors: Radka Králová, Libor Kvítek, Václav Ranc, Aleš Panáček, Radek Zbořil

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Surface–Enhanced Raman Scattering (SERS) is an optical spectroscopic technique with very good potential for sensitive detection of substances. In this research, active substrates with high enhancement were provided. Novel silver particles (nanostructures) with high roughened, flower–like morphology were prepared by reduction of cation complex [Ag(NH3)2]+ in presence of sodium borohydride as reducing agent and stabilized polyacrylic acid. The products were characterized by UV/VIS absorption spectrophotometry. Special shapes of silver particles were determined by scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM). Dispersions of this particle were put on fixed substrate to producing suitable layer for SERS. Adenine was applied as basic substance whose effect of enhancement on the layer of silver nanostructures was studied. By comparison with our work, the important influence of stabilizers, polyacrylic acid with various molecular weight and concentration, on the transfer of particles and formation of new structure was confirmed.

Keywords: metals, nanostructures, chemical reduction, Raman spectroscopy, optical properties

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Authors: Omar M. Elmabrouk

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The cutting tool, in the high-speed machining process, is consistently dealing with high localized stress at the tool tip, tip temperature exceeds 800°C and the chip slides along the rake face. These conditions are affecting the tool wear, the cutting tool performances, the quality of the produced parts and the tool life. Therefore, a thin film coating on the cutting tool should be considered to improve the tool surface properties while maintaining its bulks properties. One of the general coating processes in applying thin film for hard coating purpose is PVD magnetron sputtering. In this paper, the prediction of the effects of PVD magnetron sputtering coating process parameters, sputter power in the range of (4.81-7.19 kW), bias voltage in the range of (50.00-300.00 Volts) and substrate temperature in the range of (281.08-600.00 °C), were studied using artificial neural network (ANN). The results were compared with previously published results using RSM model. It was found that the ANN is more accurate in prediction of tool hardness, and hence, it will not only improve the tool life of the tool but also significantly enhances the efficiency of the machining processes.

Keywords: artificial neural network, hardness, prediction, titanium aluminium nitrate coating

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Authors: Janece Jean A. Polizon, Victor B. Amoroso

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Mt. Hamiguitan Range in Davao Oriental, Mindanao Island, Philippines is the only protected area with pygmy forest and a priority site for protection and conservation. This range harbors different vegetation types such as agroecosystem, dipterocarp forest, montane forest and mossy forest. This study was conducted to determine the diversity of trees and shrubs in different vegetation types of Mt. Hamiguitan Range. Transect walk and 16 sampling plots of 20 x 20 m were established in the different vegetation types. Specimens collected were classified and identified using the Flora Malesiana and type images. Assessment of status was determined based on International Union for the Conservation of Nature (IUCN). There were 223 species of trees, 141 genera and 71 families. Of the vegetation types, the pygmy forest obtained a comparatively high diversity value of H=1.348 followed by montane forest with H=1.284. The high species importance value (SIV) of Diospyros philippinensis for trees indicates that these species have an important role in regulating the stability of the ecosystem. The tree profile of the pygmy forest is different due to the ultramafic substrate causing the dwarfness of the trees. These forest types should be given high priority for protection and conservation.

Keywords: diversity, Mt Hamiguitan, vegetation, trees, shrubs

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Authors: Bahattin Duzgun, Adem Kocyigit, Demet Tatar, Ahmet Battal

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Tin oxide thin films are semiconductor materials highly transparent and with high mechanical and chemical stability, except for their interactions with oxygen atoms at high temperature. Many dopants, such as antimony (Sb), arsenic (As), fluorine (F), indium (In), molybdenum and (Mo) etc. have been used to improve the electrical properties of tin oxide films. Among these, Sb and F are found to be the most commonly used dopants for solar cell layers. Also Tin oxide tin films investigated and characterized by researchers different film deposition and analysis method. In this study, tin oxide thin films are deposited on glass substrate by spin coating technique and characterized by FTIR and AFM. FTIR spectroscopy revealed that all films have O-Sn-O and Sn-OH vibration bonds not changing with layer effect. AFM analysis indicates that all films are homogeneity and uniform. It can be seen that all films have needle shape structure in their surfaces. Uniformity and homogeneity of the films generally increased for increasing layers. The results found in present study showed that doubly doped SnO2 thin films is a good candidate for solar cells and other optoelectronic and technological applications.

Keywords: doubly doped, spin coating, FTIR analysis, AFM analysis

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Authors: J. Skibinski, P. Caban, T. Wejrzanowski, K. J. Kurzydlowski

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In the present study numerical simulations of epitaxial growth of gallium nitride in Metal Organic Vapor Phase Epitaxy reactor AIX-200/4RF-S are addressed. The aim of this study was to design the optimal fluid flow and thermal conditions for obtaining the most homogeneous product. Since there are many agents influencing reactions on the crystal growth area such as temperature, pressure, gas flow or reactor geometry, it is difficult to design optimal process. Variations of process pressure and hydrogen mass flow rates have been considered. According to the fact that it’s impossible to determine experimentally the exact distribution of heat and mass transfer inside the reactor during crystal growth, detailed 3D modeling has been used to get an insight of the process conditions. Numerical simulations allow to understand the epitaxial process by calculation of heat and mass transfer distribution during growth of gallium nitride. Including chemical reactions in the numerical model allows to calculate the growth rate of the substrate. The present approach has been applied to enhance the performance of AIX-200/4RF-S reactor.

Keywords: computational fluid dynamics, finite volume method, epitaxial growth, gallium nitride

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Authors: Angie Quevedo, Juan Bussi, Nestor Tancredi, Juan Fajardo-Díaz, Florentino López-Urías, Emilio Muñóz-Sandoval

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In this work, we study the carbon nanotubes (CNTs) formation by catalytic chemical vapor deposition (CCVD) over a catalyst with 20 % of Ni supported over La₂Zr₂O₇ (Ni20LZO). The high C solubility of Ni made it one of the most used in CNTs synthesis. Nevertheless, Ni presents also sintering and coalescence at high temperature. These troubles can be reduced by choosing a suitable support. We propose La₂Zr₂O₇ as for this matter since the incorporation of Ni by co-precipitation and calcination at 900 °C allows a good dispersion and interaction of the active metal (in the oxidized form, NiO) with this support. The CCVD was performed using 1 g of Ni20LZO at 950 °C during 30 min in Ar:H₂ atmosphere (2.5 L/min). The precursor, benzylamine, was added by a nebulizer-sprayer. X ray diffraction study shows the phase separation of NiO and La₂Zr₂O₇ after the calcination and the reduction to Ni after the synthesis. Raman spectra show D and G bands with a ID/IG ratio of 0.75. Elemental study verifies the incorporation of 1% of N. Thermogravimetric analysis shows the oxidation process start at around 450 °C. Future studies will determine the application potential of the samples.

Keywords: N doped carbon nanotubes, catalytic chemical vapor deposition, nickel catalyst, bimetallic oxide

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Authors: Folorunso Omoniyi, Peter Olubambi, Rotimi Sadiku

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Thermal barrier coating (TBC) system is used in both aero engines and other gas turbines to offer oxidation protection to superalloy substrate component. In the present work, it shows the ability of a new fabrication technique to develop rapidly new coating composition and microstructure. The compact powders were prepared by Powder Metallurgy method involving powder mixing and the bond coat was synthesized through the application of Spark Plasma Sintering (SPS) at 10500C to produce a fully dense (97%) NiCrAl bulk samples. The influence of sintering temperature on the hardness of NiCrAl, done by Micro Vickers hardness tester, was investigated. And Oxidation test was carried out at 1100oC for 20h, 40h, and 100h. The resulting coat was characterized with optical microscopy, scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX) and x-ray diffraction (XRD). Micro XRD analysis after the oxidation test revealed the formation of protective oxides and non-protective oxides.

Keywords: high-temperature oxidation, powder metallurgy, spark plasma sintering, thermal barrier coating

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Authors: Jeremiah L. Chukwuneke, Obiora E. Anisiji, Chinonso H. Achebe, Paul C. Okolie

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This paper developed a mathematical model of a commercial biogas plant for urban area clean energy requirement. It identified biodegradable waste materials like domestic/city refuse as economically viable alternative source of energy. The mathematical formulation of the proposed gas plant follows the fundamental principles of thermodynamics, and further analyses were accomplished to develop an algorithm for evaluating the plant performance preferably in terms of daily production capacity. In addition, the capacity of the plant is equally estimated for a given cycle of operation and presented in time histories. A nominal 1500 m3 power gas plant was studied characteristically and its performance efficiency evaluated. It was observed that the rate of bio gas production is essentially a function of the reactor temperature, pH, substrate concentration, rate of degradation of the biomass, and the accumulation of matter in the system due to bacteria growth. The results of this study conform to a very large extent with reported empirical data of some existing plant and further model validations were conducted in line with classical records found in literature.

Keywords: energy and mass conservation, specific growth rate, thermophilic bacteria, temperature, rate of bio gas production

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Authors: Ramandeep Kaur, Ashok Kumar Malik

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Fabric Phase Sorptive Extraction (FPSE) combined with Gas chromatography Mass Spectrometry (GCMS) has been developed for the determination of nineteen organochlorine pesticides in various aqueous samples. The method consolidates the features of sol-gel derived microextraction sorbents with rich surface chemistry of cellulose fabric substrate which could directly extract sample from complex sample matrices and incredibly improve the operation with decreased pretreatment time. Some vital parameters such as kind and volume of extraction solvent and extraction time were examinedand optimized. Calibration curves were obtained in the concentration range 0.5-500 ng/mL. Under the optimum conditions, the limits of detection (LODs) were in the range 0.033 ng/mL to 0.136 ng/mL. The relative standard deviations (RSDs) for extraction of 10 ng/mL 0f OCPs were less than 10%. The developed method has been applied for the quantification of these compounds in aqueous and fruit juice samples. The results obtained proved the present method to be rapid and feasible for the determination of organochlorine pesticides in aqueous samples.

Keywords: fabric phase sorptive extraction, gas chromatography-mass spectrometry, organochlorine pesticides, sample pretreatment

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Authors: Buta Singh Sidhu, Sukhpal Singh Chatha, Hazoor Singh Sidhu

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In the present investigation, 75Cr3C2-25NiCr coating was deposited on T91 boiler tube steel substrate by high velocity oxy-fuel (HVOF) process to enhance high-temperature corrosion resistance. High-temperature performance of bare, as well as HVOF-coated steel specimens was evaluated for 1500 h under cyclic conditions in the platen superheater zone coal-fired boiler, where the temperature was around 900 °C. Experiments were carried out for 15 cycles each of 100 h duration followed by 1 h cooling at ambient temperature. The performance of the bare and coated specimens was assessed via metal thickness loss corresponding to the corrosion scale formation and the depth of internal corrosion attack. 75Cr3C2-25NiCr coating deposited on T91 steel imparted better hot corrosion resistance than the uncoated steel. Inferior resistance of bare T91 steel is attributed to the formation of pores and loosely bounded oxide scale rich in Fe2O3.

Keywords: 75Cr3C2-25NiCr, HVOF process, boiler steel, coal fired boilers

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Authors: Chiang-Ho Cheng, An-Shik Yang, Hon-Yi Cheng, Ming-Yu Lai

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This paper presents the design and fabrication of a novel piezoelectric actuator for a gas micropump with check valve having the advantages of miniature size, light weight and low power consumption. The micropump is designed to have eight major components, namely a stainless steel upper cover layer, a piezoelectric actuator, a stainless steel diaphragm, a PDMS chamber layer, two stainless steel channel layers with two valve seats, a PDMS check valve layer with two cantilever-type check valves and an acrylic substrate. A prototype of the gas micropump, with a size of 52 mm × 50 mm × 5.0 mm, is fabricated by precise manufacturing. This device is designed to pump gases with the capability of performing the self-priming and bubble-tolerant work mode by maximizing the stroke volume of the membrane as well as the compression ratio via minimization of the dead volume of the micropump chamber and channel. By experiment apparatus setup, we can get the real-time values of the flow rate of micropump and the displacement of the piezoelectric actuator, simultaneously. The gas micropump obtained higher output performance under the sinusoidal waveform of 250 Vpp. The micropump achieved the maximum pumping rates of 1185 ml/min and back pressure of 7.14 kPa at the corresponding frequency of 120 and 50 Hz.

Keywords: PDMS, check valve, micropump, piezoelectric

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Authors: Gizachew Belay Adugna

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Perovskite solar cells (PSCs) shows rapid development as an emerging photovoltaic material; however, the fast device degradation due to the organic nature, mainly hole transporting material (HTM) and lack of robust and reliable upscaling process for photovoltaic module hindered its commercialization. Herein, HTM molecules with/without fluorine-substituted cyclopenta[2,1-b;3,4-b’]dithiophene derivatives (HYC-oF, HYC-mF, and HYC-H) were developed for PSCs application. The fluorinated HTM molecules exhibited better hole mobility and overall charge extraction in the devices mainly due to strong molecular interaction and packing in the film. Thus, the highest power conversion efficiency (PCE) of 19.64% with improved long stability was achieved for PSCs based on HYC-oF HTM. Moreover, the fluorinated HYC-oF demonstrated excellent film processability in a larger-area substrate (10 cm×10 cm) prepared sequentially with the absorption perovskite underlayer via a scalable bar coating process in ambient air and owned a higher PCE of 18.49% compared to the conventional spiro-OMeTAD (17.51%). The result demonstrates a facile development of HTM towards stable and efficient PSCs for future industrial-scale PV modules.

Keywords: perovskite solar cells, upscaling film coating, power conversion efficiency, solution processing

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Authors: Yiying Xiao, Chia Wei Lim, Jinquan Chang, Qixin Yuan, Lei Wang, Ning Yan

Abstract:

Electrocatalytic reductive amination (ERA) offers an attractive way to make organonitrogen chemicals from renewable feedstock. Here, we report carbon nanotube (CNT) as an effective catalyst for the ERA of biomass-derivable α-keto acids into amino acids using NH₃ as the nitrogen source. Through a facile ball milling (BM) treatment, the intrinsic defects in the CNTs were increased while the electrocatalytic activity of CNTs converting 2-ketoglutaric acid into glutamic acid was enhanced by approximately seven times. A high Faradaic efficiency (FE) of ~90% with a corresponding glutamic acid formation rate up to 180.9 mmol•g⁻¹𝒸ₐₜt•h⁻¹ was achieved, and ~60% molar yield of glutamic acid was obtained after 8 h of electrolysis. Electrokinetic analyses indicate that the BM-CNTs catalysed ERA exhibits first-order dependences on the substrate and NH₃, with a rate-determining step (RDS) involving the first electron transfer. Following this protocol, a number of amino acids were prepared with moderate to high FEs and formation rates. Significantly, we synthesised long carbon chain amino acids, which typically face lower yields using the existing methods.

Keywords: amino acids, carbon nanotubes, electrocatalysis, reductive amination, α-keto acids

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Authors: Abhipsa Mohanty, Harit Jha

Abstract:

The world's energy demands are continuing to rise, resulting in a worldwide energy crisis and environmental pollution. Because of finite, declining supply and environmental damage, reliance on fossil fuels is unsustainable. As a result, experts are concentrating on alternative, renewable, and carbon-free energy sources. Energy sources that are both environmentally and economically sustainable are required. Microbial fuel cells (MFCs) have recently received a lot of attention due to their low operating temperatures and ability to use a variety of biodegradable substrates as fuel. There are single-chamber MFCs as well as traditional MFCs with anode and cathode compartments. Bioelectricity is produced when microorganisms actively catabolize substrate. MFCs can be used as a power source in small devices like biosensors. Understanding of its components, microbiological processes, limiting variables, and construction designs in MFC systems must be simplified, and large-scale systems must be developed for them to be cost-effective as well as increase electricity production. The purpose of this research was to review current microbiology knowledge in the field of electricity. The manufacturing process, the materials, and procedures utilized to construct the technology, as well as the applications of MFC technology, are all covered.

Keywords: bio-electricity, exoelectrogenic bacteria, microbial fuel cells, soil microorganisms

Procedia PDF Downloads 93

Authors: Anicet Dansou

Abstract:

Textile reinforced concrete (TRC)is increasingly used nowadays in various fields, in particular civil engineering, where it is mainly used for the reinforcement of damaged reinforced concrete structures. TRC is a composite material composed of multi- or uni-axial textile reinforcements coupled with a fine-grained cementitious matrix. The TRC composite is an alternative solution to the traditional Fiber Reinforcement Polymer (FRP) composite. It has good mechanical performance and better temperature stability but also, it makes it possible to meet the criteria of sustainable development better.TRCs are highly anisotropic composite materials with nonlinear hardening behavior; their macroscopic behavior depends on multi-scale mechanisms. The characterization of these materials through numerical simulation has been the subject of many studies. Since TRCs are multiscale material by definition, numerical multi-scale approaches have emerged as one of the most suitable methods for the simulation of TRCs. They aim to incorporate information pertaining to microscale constitute behavior, mesoscale behavior, and macro-scale structure response within a unified model that enables rapid simulation of structures. The computational costs are hence significantly reduced compared to standard simulation at a fine scale. The fine scale information can be implicitly introduced in the macro scale model: approaches of this type are called non-classical. A representative volume element is defined, and the fine scale information are homogenized over it. Analytical and computational homogenization and nested mesh methods belong to these approaches. On the other hand, in classical approaches, the fine scale information are explicitly introduced in the macro scale model. Such approaches pertain to adaptive mesh refinement strategies, sub-modelling, domain decomposition, and multigrid methods This research presents the main principles of numerical multiscale approaches. Advantages and limitations are identified according to several criteria: the assumptions made (fidelity), the number of input parameters required, the calculation costs (efficiency), etc. A bibliographic study of recent results and advances and of the scientific obstacles to be overcome in order to achieve an effective simulation of textile reinforced concrete in civil engineering is presented. A comparative study is further carried out between several methods for the simulation of TRCs used for the structural reinforcement of reinforced concrete structures.

Keywords: composites structures, multiscale methods, numerical modeling, textile reinforced concrete

Procedia PDF Downloads 108

Authors: Md. Maksudur Rahman Khan, Chee Wai Woon, Huei Ruey Ong, Vignes Rasiah, Chin Kui Cheng, Kar Min Chan, E. Baranitharan

Abstract:

The present work represents a preparation of non-precious iron-based electrocatalyst (FeN) for ORR in air-cathode microbial fuel cell by pyrolysis treatment. Iron oxalate which recovered from the industrial wastewater and Phenanthroline (Phen) were used as the iron and nitrogen precursors, respectively in preparing FeN catalyst. The performance of as prepared catalyst (FeN) was investigated in a single chambered air cathode MFC in which anaerobic sludge was used as inoculum and palm oil mill effluent as substrate. The maximum open circuit potential (OCV) and the highest power density recorded were 0.543 V and 4.9 mW/m2, respectively. Physical characterization of FeN was elucidated by using Brunauner Emmett Teller (BET), X-Ray Diffraction (XRD) analysis and Field Emission Scanning Electron Microscopy (FESEM) while the electrochemical properties were characterized by cyclic voltammetry (CV) analysis. The presence of biofilm on anode surface was examined using FESEM and confirmed using Infrared Spectroscopy and Thermogravimetric Analysis. The findings of this study demonstrated that FeN is electrochemically active and further modification is needed to increase the ORR catalytic activity.

Keywords: iron based catalyst, microbial fuel cells, oxygen reduction reaction, palm oil mill effluent

Procedia PDF Downloads 334