Search results for: long term effect

Authors: N. Massoum, A. Guen. Bouazza, B. Bouazza, A. El Ouchdi

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The progress of industry integrated circuits in recent years has been pushed by continuous miniaturization of transistors. With the reduction of dimensions of components at 0.1 micron and below, new physical effects come into play as the standard simulators of two dimensions (2D) do not consider. In fact the third dimension comes into play because the transverse and longitudinal dimensions of the components are of the same order of magnitude. To describe the operation of such components with greater fidelity, we must refine simulation tools and adapted to take into account these phenomena. After an analytical study of the static characteristics of the component, according to the different operating modes, a numerical simulation is performed of field-effect transistor with submicron gate MESFET GaInP. The influence of the dimensions of the gate length is studied. The results are used to determine the optimal geometric and physical parameters of the component for their specific applications and uses.

Keywords: Monte Carlo simulation, transient electron transport, MESFET device, GaInP

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Authors: Hossein Arfaeinia, Azam Nadali, Zahra Asadgol, Mohammad Fahiminia

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Indoor and outdoor particulate matters (PM) were monitored in 20 residential buildings in a two-part study. In part I, the levels of indoor and outdoor PM₁₀, PM₂.₅ and PM₁ was measured using real time GRIMM dust monitors. In part II, the effect of negative air ions (NAIs) method was investigated on the reduction of indoor concentration of PM in these residential buildings. Hourly average concentration and standard deviation (SD) of PM₁₀ in indoor and outdoor at residential buildings were 90.1 ± 33.5 and 63.5 ± 27.4 µg/ m3, respectively. Indoor and outdoor concentrations of PM₂.₅ in residential buildings were 49.5 ± 18.2 and 39.4± 18.1 µg/ m3 and for PM₁ the concentrations were 6.5 ± 10.1and 4.3 ± 7.7 µg/ m3, respectively. Indoor/outdoor (I/O) ratios and concentrations of all size fractions of PM were strongly correlated with wind speed and temperature whereas a good relationship was not observed between humidity and I/O ratios of PM. We estimated that nearly 71.47 % of PM₁₀, 79.86 % of PM₂.₅ and of 61.25 % of PM₁ in indoor of residential buildings can be removed by negative air ions.

Keywords: particle matter (PM), indoor air, negative air ions (NAIs), residential building

Procedia PDF Downloads 238

Authors: Shakila N. Senarath, Dinesh Asanka, Janaka Wijayanayake

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The necessity of cosmetic products is arising to fulfill consumer needs of personality appearance and hygiene. A cosmetic product consists of various chemical ingredients which may help to keep the skin healthy or may lead to damages. Every chemical ingredient in a cosmetic product does not perform on every human. The most appropriate way to select a healthy cosmetic product is to identify the texture of the body first and select the most suitable product with safe ingredients. Therefore, the selection process of cosmetic products is complicated. Consumer surveys have shown most of the time, the selection process of cosmetic products is done in an improper way by consumers. From this study, a content-based system is suggested that recommends cosmetic products for the human factors. To such an extent, the skin type, gender and price range will be considered as human factors. The proposed system will be implemented by using Machine Learning. Consumer skin type, gender and price range will be taken as inputs to the system. The skin type of consumer will be derived by using the Baumann Skin Type Questionnaire, which is a value-based approach that includes several numbers of questions to derive the user’s skin type to one of the 16 skin types according to the Bauman Skin Type indicator (BSTI). Two datasets are collected for further research proceedings. The user data set was collected using a questionnaire given to the public. Those are the user dataset and the cosmetic dataset. Product details are included in the cosmetic dataset, which belongs to 5 different kinds of product categories (Moisturizer, Cleanser, Sun protector, Face Mask, Eye Cream). An alternate approach of TF-IDF (Term Frequency – Inverse Document Frequency) is applied to vectorize cosmetic ingredients in the generic cosmetic products dataset and user-preferred dataset. Using the IF-IPF vectors, each user-preferred products dataset and generic cosmetic products dataset can be represented as sparse vectors. The similarity between each user-preferred product and generic cosmetic product will be calculated using the cosine similarity method. For the recommendation process, a similarity matrix can be used. Higher the similarity, higher the match for consumer. Sorting a user column from similarity matrix in a descending order, the recommended products can be retrieved in ascending order. Even though results return a list of similar products, and since the user information has been gathered, such as gender and the price ranges for product purchasing, further optimization can be done by considering and giving weights for those parameters once after a set of recommended products for a user has been retrieved.

Keywords: content-based filtering, cosmetics, machine learning, recommendation system

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Authors: Hamid Havasi, Mohamad Reza Gholami Dehbalaei, Hamed Khorami, Shahram Karimi, Hamdi Abdi

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Doubly-fed induction generator (DFIG) equipped with a power converter is an efficient tool for converting mechanical energy of a variable speed system to a fixed-frequency electrical grid. Since electrical energy sources faces with production problems such as harmonics caused by nonlinear loads, so in this paper, compensation performance of DPC and FOC method on harmonics reduction of a DFIG wind turbine connected to a nonlinear load in MATLAB Simulink model has been simulated and effect of each method on nonlinear load harmonic elimination has been compared. Results of the two mentioned control methods shows the advantage of the FOC method on DPC method for harmonic compensation. Also, the fifth and seventh harmonic components of the network and THD greatly reduced.

Keywords: DFIG machine, energy conversion, nonlinear load, THD, DPC, FOC

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Authors: Saba Pajuhan, Afshin Farahbakhsh, S. M. M. Dastgheib

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Biosurfactants and bioemulsifiers are a structurally diverse group of surface-active molecules synthesized by microorganisms, they are amphipathic molecules which reduce surface and interfacial tensions and widely used in pharmaceutical, cosmetic, food and petroleum industries. In this paper, several methods of bioemulsifer synthesis and purification by Bacillus licheniformis strains (namely ACO1, PTCC 1595 and ACO4) were investigated. Strains were grown in nutrient broth with different conditions in order to get maximum production of bioemulsifer. The purification of bio emulsifier and the quality evaluation of the product was done by adding sulfuric acid (H₂SO₄) (98%), Ethanol or HCl to the solution followed by centrifuging. To determine the optimal conditions yielding the highest bioemulsifier production, the effect of various carbon and nitrogen sources, temperature, NaCl concentration, pH, O₂ levels, incubation time are indispensable and all of them were highly effective in bioemulsifiers production.

Keywords: biosurfactant, bioemulsifier, purification, surface tension, interfacial tension

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Authors: Anwar Ali Abdulla, Thekra Abdulaali Abed Al-Chaabawi, Anwar Kadhim Al-Saffar, Hussein Kadhim Al-Saffar

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Lactic acid bacteria are very significant to human health due to the production of some antimicrobial substances and ability to inhibit pathogenic bacteria. Furthermore, the bacteria are also used as starter culture in the production of various foods. The present study was focused on isolation and characterization of Lactobacillus acidophilus from yogurt and to demonstrate some of probiotic properties of these isolates. All isolates were phenotypically characterized including studying, biochemical, effect of sodium chloride and pH during growth, carbohydrates test and characterizing the antimicrobial activity of Lactobacillus acidophilus against pathogens. The present study demonstrates that Lactobacillus acidophilus produced a bacteriocin- like inhibitory substance with a broad spectrum of antimicrobial activity directed against pathogenic indicator organism suggesting its protective value against enteric pathogens.

Keywords: lactobacillus acidophilus, bacteriocin, antimicrobial activity, probiotic

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Authors: J. Marie Hicks

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The art of the poetic conjoins meaning and symbolism with imagery and rhythm. Perhaps the reader might read this opening sentence as 'The art of the poetic combines meaning and symbolism with imagery and rhythm,' which holds a similar message, but is not quite the same. The reader understands that these factors are combined in this literary form, but to gain a sense of the conjoining of these factors, the reader is forced to consider that these aspects of poetry are not simply combined, but actually adjoin, abut, skirt, or touch in the poetic form. This alternative word choice is an example of substitutional inference. Poetry is, ostensibly, a literary form where language is used precisely or creatively to evoke specific images or emotions for the reader. Often, the reader can predict a coming rhyme or descriptive word choice in a poem, based on previous rhyming pattern or earlier imagery in the poem. However, there are instances when the poet uses an unexpected word choice to create multiple meanings and connections. In these cases, the reader is presented with an unusual phrase or image, requiring that they think about what that image is meant to suggest, and their mind also suggests the word they expected, creating a second, overlying image or meaning. This is what is meant by the term 'substitutional inference.' This is different than simply using a double entendre, a word or phrase that has two meanings, often one complementary and the other disparaging, or one that is innocuous and the other suggestive. In substitutional inference, the poet utilizes an unanticipated word that is either visually or phonetically similar to the expected word, provoking the reader to work to understand the poetic phrase as written, while unconsciously incorporating the meaning of the line as anticipated. In other words, by virtue of a word substitution, an inference of the logical word choice is imparted to the reader, while they are seeking to rationalize the word that was actually used. There is a substitutional inference of meaning created by the alternate word choice. For example, Louise Bogan, 4th Poet Laureate of the United States, used substitutional inference in the form of homonyms, malapropisms, and other unusual word choices in a number of her poems, lending depth and greater complexity, while actively engaging her readers intellectually with her poetry. Substitutional inference not only adds complexity to the potential interpretations of Bogan’s poetry, as well as the poetry of others, but provided a method for writers to infuse additional meanings into their work, thus expressing more information in a compact format. Additionally, this nuancing enriches the poetic experience for the reader, who can enjoy the poem superficially as written, or on a deeper level exploring gradations of meaning.

Keywords: poetic inference, poetic word play, substitutional inference, word substitution

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Authors: Mohammad Mirjalili, Maryam Mohammdi, Loghman Karimi

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In this study, synthesis of zinc oxide nanoparticles was carried out along with the hydrolysis of Polyethylene terephthalate using sodium hydroxide to increase the surface activity and enhance the nanoparticles adsorption. The polyester fabrics were treated with zinc acetate and sodium hydroxide at ultrasound bath, resulting in the formation of ZnO nanospheres. The presence of zinc oxide on the surface of the polyethylene terephthalate was confirmed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The self-cleaning property of treated polyethylene terephthalate was evaluated through discoloring methylene blue stain under sunlight irradiation. The antibacterial activities of the samples against two common pathogenic bacteria including Escherichia coli and Staphylococcus aureus were also assessed. The results indicated that the photocatalytic and antibacterial activities of the ultrasound treated polyethylene terephthalate improved significantly.

Keywords: zinc oxide, polyethylene terephthalate, self-cleaning, antibacterial

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Authors: T. J. Jemi Jeya, V. Sriram

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Pile Supported Caisson breakwater is an ecofriendly breakwater very useful in coastal zone protection. The model is developed by considering the advantages of both caisson breakwater and pile supported breakwater, where the top portion is a vertical or quarter circle caisson and the bottom portion consists of a pile supported breakwater defined as Vertical Pile Supported Breakwater (VPSCB) and Quarter-circle Pile Supported Breakwater (QPSCB). The study mainly focuses on comparison of run up over VPSCB and QPSCB under oblique waves. The experiments are carried out in a shallow wave basin under different water depths (d = 0.5 m & 0.55 m) and under different oblique regular waves (0⁰, 15⁰, 30⁰). The run up over the surface is measured by placing two run up probes over the surface at 0.3 m on both sides from the centre of the model. The results show that the non-dimensional shoreward run up shows slight decrease with respect to increase in angle of wave attack.

Keywords: Caisson breakwater, pile supported breakwater, quarter circle breakwater, vertical breakwater

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Authors: M. Amelsakhi, A. Sohrabi-Bidar, A. Shareghi

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One of the most important issues about the structural damages caused by earthquake is the evaluating of the spectral response of the site on which the construction is built. This fact has demonstrated during many earlier earthquakes and many researchers’ reports have concerned with it. According to these reports, features of the site materials and geometry of the ground surface are considered the main factors. This study concentrates on the specific form of topographies like hills. Assessing of spectral responses of different points on the hills and beside demonstrates considerable differences between 1D and 2D methods of geotechnical analyses. A general trend of amplifications on the top of the hills and de-amplifications near the toe of the hills has been appeared within the acceleration, velocity and displacement response spectrums of horizontal motion. Evaluating of spectral responses of different sizes of the hills revealed that as much as the hill-size enlarges differences between spectral responses of 1D and 2D analyses transfers to longer range of periods and becomes wider.

Keywords: topography effect, amplification ratio, response spectrum, earth resources engineering

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Authors: Lingmao Xu, Hui Zhou

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Ge film is widely used in infrared optical systems. Because of the special requirements of space application, it is usually used in low temperature. The refractive index of Ge film is always changed with the temperature which has a great effect on the manufacture of high precision infrared optical film. Specimens of Ge single film were deposited at ZnSe substrates by EB-PVD method. During temperature range 80K ~ 300K, the transmittance of Ge single film within 2 ~ 15 μm were measured every 20K by PerkinElmer FTIR cryogenic testing system. By the full spectrum inversion method fitting, the relationship between refractive index and wavelength within 2 ~ 12μm at different temperatures was received. It can be seen the relationship consistent with the formula Cauchy, which can be fitted. Then the relationship between refractive index of the Ge film and temperature/wavelength was obtained by fitting method based on formula Cauchy. Finally, the designed value obtained by the formula and the measured spectrum were compared to verify the accuracy of the formula.

Keywords: infrared optical film, low temperature, thermal refractive coefficient, Ge film

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Authors: S. Kumar, Rajesh Kumar, S. Mandal

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Fiber Reinforced Polymer (FRP) is gaining popularity in many branch of engineering and various applications due to their light weight, specific strength per unit weight and high stiffness in particular direction. As the strength of material is high it can be used in thin walled structure as industrial roof sheds satisfying the strength constraint with comparatively lesser thickness. Analysis of bending behavior of FRP panel has been done here with variation in oriented angle of stiffener panels, fiber orientation, aspect ratio and boundary conditions subjected to transverse loading by using Finite Element Method. The effect of fiber orientation and thickness of ply has also been studied to determine the minimum thickness of ply for optimized section of stiffened FRP panel.

Keywords: bending behavior, fiber reinforced polymer, finite element method, orientation of stiffeners

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Authors: Hassina Hafida Boukhalfa, Mathieu Massinon, Fréderic Lebeau, Mohamed Belhamra

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Drop behaviour during impact affects retention. The increase of adhesion is usually seen as the objective when applying crop protection products, while bouncing and shattering are seen as detrimental to spray retention. However, observation of drop impacts using high speed shadow graphy shows that fragmentation can occur in Wenzel wetting regime. In this case, a part of the drop sticks on the surface, what contributes to retention. Using simultaneous measurements of drop impacts with high speed imaging and of retention with fluorometry for 3 spray mixtures on excised barley leaves allowed us to observe that about 50% of the drops fragmented in Wenzel state remain on the leaf. Depending on spray mixture, these impact outcomes accounted for 25 to 50% of retention, the higher contribution being correlated with bigger VMD (Volume Median Diameter). This contribution is non-negligible and should be considered when a modelling of spray retention process is performed.

Keywords: drop impact, retention, fluorometry, high speed imaging

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Authors: Frank Alexis, Jenny Antonia Rodriguez Leon, Cristobal Leonardo Dominguez Borbor, Mery Rosario Ramirez Munoz

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The shrimp industry has increased in the last years to the point of becoming one of the most dynamic industries. However, the appearance of diseases that significantly affect the production of shrimps has been an obstacle for the shrimp industry. We hypothesized that natural fibers from biodiversity can stimulate the immune system to prevent shrimp diseases like vibriosis. In this project, we extracted the fibers from vegetal sources in Ecuador and characterized them using common techniques like XRD, SEM, and then we tested the effect of fibers as immunostimulants for shrimps in-vitro and in-vivo using small aquarium and large pools. Our results demonstrate that vegetal fibers can significantly increase the survival of shrimps. Moreover, the production of shrimps in a large pool was significantly increased. Lastly, the test of color and taste successfully surpass the control group of shrimps not treated with fiber food supplements.

Keywords: fibers, immunostimulant, shrimp, vibriosis

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Authors: Motahare Aali, Fatemeh Tajik

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Here, we investigate the sensitivity the Casimir force and consequently dynamical actuation of a three-layer microswitch to some ambient conditions. In fact, we have considered the effect of optical properties on the stable operation of the microswitch for both good (e.g. metals) and poor conductors via a three layer Casimir oscillator. Indeed, gold (Au) has been chosen as a good conductor which is widely used for Casimir force measurements, and highly doped conductive silicon carbide (SiC) has been considered as a poor conductor which is a promising material for device operating under harsh environments. Also, the intervening stratum is considered ethanol or water. It is also supposed that the microswitches are frictionless and autonomous. Using reduction factor diagrams and bifurcation curves, it has been shown how performance of the microswitches is sensitive to temperature and intervening stratum, moreover it is investigated how the conductivity of the components can affect this sensitivity.

Keywords: Casimir force, optical properties, Lifshitz theory, dielectric function

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Authors: M. Hosseini, N. Ghorbani Amirabad, M. Zhian

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Seismic design codes accept structural and nonstructural damages after the sever earthquakes (provided that the building is prevented from collapse), so that in many cases demolishing and reconstruction of the building is inevitable, and this is usually very difficult, costly and time consuming. Therefore, designing and constructing of buildings in such a way that they can be easily repaired after earthquakes, even major ones, is quite desired. For this purpose giving the possibility of rocking or see-saw motion to the building structure, partially or as a whole, has been used by some researchers in recent decade .the central support which has a main role in creating the possibility of see-saw motion in the building’s structural system. In this paper, paying more attention to the key role of the central fuse and support, an innovative energy dissipater which can act as the central fuse and support of the building with seesaw motion is introduced, and the process of reaching an optimal geometry for that by using finite element analysis is presented. Several geometric shapes were considered for the proposed central fuse and support. In each case the hysteresis moment rotation behavior of the considered fuse were obtained under simultaneous effect of vertical and horizontal loads, by nonlinear finite element analyses. To find the optimal geometric shape, the maximum plastic strain value in the fuse body was considered as the main parameter. The rotational stiffness of the fuse under the effect of acting moments is another important parameter for finding the optimum shape. The proposed fuse and support can be called Yielding Curved Bars and Clipped Hemisphere Core (YCB&CHC or more briefly YCB) energy dissipater. Based on extensive nonlinear finite element analyses it was found out the using rectangular section for the curved bars gives more reliable results. Then, the YCB energy dissipater with the optimal shape was used in a structural model of a 12 story regular building as its central fuse and support to give it the possibility of seesaw motion, and its seismic responses were compared to those of a the building in the fixed based conditions, subjected to three-components acceleration of several selected earthquakes including Loma Prieta, Northridge, and Park Field. In building with see-saw motion some simple yielding-plate energy dissipaters were also used under circumferential columns.The results indicated that equipping the buildings with central and circumferential fuses result in remarkable reduction of seismic responses of the building, including the base shear, inter story drift, and roof acceleration. In fact by using the proposed technique the plastic deformations are concentrated in the fuses in the lowest story of the building, so that the main body of the building structure remains basically elastic, and therefore, the building can be easily repaired after earthquake.

Keywords: rocking mechanism, see-saw motion, finite element analysis, hysteretic behavior

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Authors: Khaled ElEbyary, Ramy Shabara

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L2 research has generally acknowledged the role of noticing in language learning. The role of teacher feedback is to trigger learners’ noticing of errors and direct the writing process. Recently L2 learners are seemingly using computerized applications which provide corrective feedback (CF) at different stages of writing (i.e., during and after writing). This study aimed principally to answer the question, “Is noticing likely to be maximized when feedback on erroneous output is electronically provided either during or after the composing stage, or does teacher annotated feedback have a stronger effect?”. Seventy-five participants were randomly distributed into four groups representing four conditions. These include receiving automated feedback at the composing stage, automated feedback after writing, teacher feedback, and no feedback. Findings demonstrate the impact of CF on writing and the intensity of noticing certain language areas at different writing stages and from different feedback sources.

Keywords: written corrective feedback, error correction, noticing, automated written corrective feedback, L2 acquisition

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Authors: Mohammad ASadian, Samira RajiAsadabadi

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Osteoporosis is very common, particularly in post-menopausal women and is characterized by a decrease in bone mass and strength. Osteoporosis also affects the jawbone and it is considered a potential contraindication to the placement of dental implants. The present paper reviews the literature regarding the effect of osteoporosis on the osseointegration of implants. Experimental models have shown that osteoporosis affects the process of osseointegration, which can be reversed by treatment. However, studies in subjects with osteoporosis have shown no differences in the survival of the implants compared to healthy individuals. Therefore, osteoporosis cannot be considered a contraindication for implant placement. Oral bisphosphonates are the most commonly used pharmacological agents in the treatment of osteoporosis. Although there have been cases of osteonecrosis of the jaw in patients treated with bisphosphonates, they are very rare and it is more usually associated with intravenous bisphosphonates in patients with neoplasms or other serious diseases. Nevertheless, patients treated with bisphosphonates must be informed in writing about the possibility of this complication and must give informed consent. Ceasing to use of bisphosphonates before implant placement does not seem to be necessary.

Keywords: Osteoporosis, dental implant, bisphosphonates, survival

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Authors: Nemat Sokhandan Bashir

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Threats from viruses to agricultural crops could be even larger than the losses caused by the other pathogens because, in many cases, the viral infection is latent but crucial from an epidemic point of view. Wild vegetation can be a source of many viruses that eventually find their destiny in crop plants. Although often asymptomatic in wild plants due to adaptation, they can potentially cause serious losses in crops. Therefore, exploring viruses in wild vegetation is very important. Recently, omics have been quite useful for exploring plant viruses from various plant sources, especially wild vegetation. For instance, we have discovered viruses such as Ambrossia asymptomatic virus I (AAV-1) through the application of metagenomics from Oklahoma Prairie Reserve. Accordingly, extracts from randomly-sampled plants are subjected to high speed and ultracentrifugation to separated virus-like particles (VLP), then nucleic acids in the form of DNA or RNA are extracted from such VLPs by treatment with phenol—chloroform and subsequent precipitation by ethanol. The nucleic acid preparations are separately treated with RNAse or DNAse in order to determine the genome component of VLPs. In the case of RNAs, the complementary cDNAs are synthesized before submitting to DNA sequencing. However, for VLPs with DNA contents, the procedure would be relatively straightforward without making cDNA. Because the length of the nucleic acid content of VPLs can be different, various strategies are employed to achieve sequencing. Techniques similar to so-called "chromosome walking" may be used to achieve sequences of long segments. When the nucleotide sequence data were obtained, they were subjected to BLAST analysis to determine the most related previously reported virus sequences. In one case, we determined that the novel virus was AAV-l because the sequence comparison and analysis revealed that the reads were the closest to the Indian citrus ringspot virus (ICRSV). AAV—l had an RNA genome with 7408 nucleotides in length and contained six open reading frames (ORFs). Based on phylogenies inferred from the replicase and coat protein ORFs of the virus, it was placed in the genus Mandarivirus.

Keywords: wild, plant, novel, metagenomics

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Authors: H. M. Wilhelm, P. O. Fernandes, L. P. Dill, C. Steffens, K. G. Moscon, S. M. Peres, V. Bender, T. Marchesan, J. B. Ferreira Neto

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Deterioration of insulating oil is a natural process that occurs during transformers operation. However, this process can be accelerated by some factors, such as oxygen, high temperatures, metals and, moisture, which rapidly reduce oil insulating capacity and favor transformer faults. Parts of building materials of a transformer can be degraded and yield soluble compounds and insoluble particles that shorten the equipment life. Physicochemical tests, dissolved gas analysis (including propane, propylene and, butane), volatile and furanic compounds determination, besides quantitative and morphological analyses of particulate are proposed in this study in order to correlate transformers building materials degradation with insulating oil characteristics. The present investigation involves tests of medium temperature overheating simulation by means of an electric resistance wrapped with the following materials immersed in mineral insulating oil: test I) copper, tin, lead and, paper (heated at 350-400 °C for 8 h); test II) only copper (at 250 °C for 11 h); and test III) only paper (at 250 °C for 8 h and at 350 °C for 8 h). A different experiment is the simulation of electric arc involving copper, using an electric welding machine at two distinct energy sets (low and high). Analysis results showed that dielectric loss was higher in the sample of test I, higher neutralization index and higher values of hydrogen and hydrocarbons, including propane and butane, were also observed. Test III oil presented higher particle count, in addition, ferrographic analysis revealed contamination with fibers and carbonized paper. However, these particles had little influence on the oil physicochemical parameters (dielectric loss and neutralization index) and on the gas production, which was very low. Test II oil showed high levels of methane, ethane, and propylene, indicating the effect of metal on oil degradation. CO₂ and CO gases were formed in the highest concentration in test III, as expected. Regarding volatile compounds, in test I acetone, benzene and toluene were detected, which are oil oxidation products. Regarding test III, methanol was identified due to cellulose degradation, as expected. Electric arc simulation test showed the highest oil oxidation in presence of copper and at high temperature, since these samples had huge concentration of hydrogen, ethylene, and acetylene. Particle count was also very high, showing the highest release of copper in such conditions. When comparing high and low energy, the first presented more hydrogen, ethylene, and acetylene. This sample had more similar results to test I, pointing out that the generation of different particles can be the cause for faults such as electric arc. Ferrography showed more evident copper and exfoliation particles than in other samples. Therefore, in this study, by using different combined analytical techniques, it was possible to correlate insulating oil characteristics with possible contaminants, which can lead to transformers failure.

Keywords: Ferrography, gas analysis, insulating mineral oil, particle contamination, transformer failures

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Authors: S. Ghoudelbourk, A. Omeiri, D. Dib, H. Cheghib

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This paper shows that we can improve the performance of the auto-adjustable electric machines if a fractional dynamic is considered in the algorithm of the controlling order. This structure is particularly interested in the separate control of active and reactive power of the double-fed induction generator (DFIG) of wind power conversion chain. Fractional regulators are used in the regulation of chain of powers. Knowing that, usually, the source of DFIG is provided by converters through controlled rectifiers, all this system makes the currents of lines strongly polluted that can have a harmful effect for the connected loads and sensitive equipment nearby. The solution to overcome these problems is to replace the power of the rotor DFIG by multilevel inverters supplied by PV which improve the THD. The structure of the adopted adjustment is tested using Matlab/Simulink and the results are presented and analyzed for a variable wind.

Keywords: DFIG, fractional regulator, multilevel inverters, PV

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Authors: El Metmati Abdelhaq

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Shear strength of sandy soils has been considered as the important parameter to study the stability of different civil engineering structures when subjected to monotonic, cyclic and earthquake loading conditions. The objective of this laboratory investigation is to study the influence of the fraction of low plastic fines and gradation on the mechanical behavior of sand-silt mixtures reconstituted in the laboratory. For this purpose, a series of Casagrande shear box tests were carried out on different reconstituted samples of sand-silt mixtures with various gradations at two initial relative densities (Dr = 20 and 91 %) with different fines content ranging from 0 to 40 %. The soil samples were tested under different normal stresses (100, 200 and 300 kPa). The evaluation of the data indicates that the fines content and the gradation have significant influence on the friction angle and the cohesion.

Keywords: mechanical behavior, silty sand, friction angle, cohesion, fines content

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Authors: Brahim Mahfoud

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A three-dimensional (3D) numerical technique is used to investigate the possibility of reducing the price of manufacturing some silicon-based devices, particularly those in which minor temperature gradients can significantly reduce performance. The silicon melt under the magnetic field produces Lorentz force, which can effectively suppress the flow which is caused by temperature gradients. This might allow some silicon-based products, such as solar cells, to be manufactured using a less pure, and hence less expensive. The thermocapillary effect of the silicon melt flow in thin annular pools subjected to an externally induced magnetic field was observed. The results reveal that with a strong enough magnetic field, isothermal lines change form and become concentric circles. As the amplitude of the magnetic field (Ha) grows, the azimuthal velocity and temperature at the free surface reduce, and the asymmetric 3D flow becomes axisymmetric steady when Ha surpasses a threshold value.

Keywords: magnetic field, manufacturing, silicon melt, thermocapillary

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Authors: Elsayed G. Zaki, Nora A. Hamad, Hadeel G. El-Shorbagy

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The effect of watermelon rind extract as green inhibitors for the formation of calcium sulphate scale have been investigated using conductivity measurements concurrently with the scanning electron microscopy (SEM), and optical microscopic examinations. Mineral scales were deposited from the brine solution by cathodic polarization of the steel surface. The results show up that the anti-scaling property of the extracts could be attributed to the presence of citrulline. In solution, citrulline retards calcium sulphate precipitation via formation of a complex with the calcium cations. Thin, smooth and non adherent film formed over the steel surface, under cathodic polarization, by the deposition of the calcium- citrulline complex. The stability of the aqueous extracts with time was also investigated.

Keywords: anti-scaling, scale inhibitor, green extracts, water treatment

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Authors: Estelle Abrahams, Tania Pretorius

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A joint media statement by the South African Reserve Bank, the Banking Association of South Africa, the Financial Sector Conduct Authority, and the Payments Association of South Africa was recently published, stating that the receipt or acceptance of cheques will terminate effectively on 31 December 2020. All stakeholders are urged to cease accepting or issuing cheques as a payment method. The purpose of the study is to examine the effect that the discontinuation of the usage of cheques has on bank reconciliations for the subject: economic and management sciences. A literature study was performed to gain insight into the bank reconciliation process to be able to draw conclusions on the outcome of the discontinuation of cheques on the bank reconciliation. The study found that the teaching of the bank reconciliation process will change to introduce new replacement source documents for digital payments, and this impacts the teaching of reconciling differences.

Keywords: bank reconciliation, internal control, accounting education, source documents

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Authors: Sathish K. Gurupatham, Farhad Sayedzada, Naji Dauk, Valmiki Sooklal, Laura Ruhala

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It was shown recently that small particles and powders spontaneously disperse on liquid surfaces when they come into contact with the interface for the first time. This happens due to the combined effect of the capillary force, buoyant weight of the particle and the viscous drag that the particle experiences in the liquid. The particle undergoes oscillations normal to the interface before it comes to rest on the interface. These oscillations, in turn, induce a flow on the interface which disperses the particles radially outward. This phenomenon has a significant role in the pollination of sea plants such as Ruppia in which the formation of ‘pollen rafts’ is the first step. This paper investigates, experimentally, the influence of the temperature of the liquid on which this dispersion occurs. It was observed that the frequency of oscillations of the particles decreased with the increase in the temperature of the liquid. It is because the magnitude of capillary force also decreased when the temperature of the liquid increased.

Keywords: particle dispersion, capillary force, viscous drag, oscillations

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Authors: Ana Cristina Lindsay, Sherrie Wallington, Faith Lees, Mary Greaney

Abstract:

Purpose: Latino children in low-income families are at elevated risk of becoming overweight or obese. The purpose of this study was to examine low-income Latino parents’ beliefs, parenting styles and practices related to their children’s eating and physical activity behaviors while at home. Design and Methods: Qualitative study using focus group discussions with 33 low-income Latino parents of preschool children 2 to 5 years of age. Transcripts were analyzed using thematic analysis. Results: Data analyses revealed that most parents recognize the importance of healthy eating and physical activity for their children and themselves. However, daily life demands including conflicting schedules, long working hours, financial constraints, and neighborhood safety concerns, etc., impact parents’ ability to create a home environment supportive of these behaviors. Conclusions: This study provides information about how the home environment influences low-income Latino preschool children’s eating and physical activity habits. This information is useful for pediatric nurses in their health promotion and disease prevention efforts with low-income Latino families with young children, and for the development of home-based and parenting interventions to prevent and control childhood obesity among this population group. Practice Implications: Pediatric nurses can facilitate communication, provide education, and offer guidance to low-income Latino parents that support their children’s development of early healthy eating and physical activity habits, while taking into account daily life barriers faced by families. Moreover, nurses can play an important role in the integration and coordination of home-visitation to complement office-based visits and provide a continuum of care to low-income Latino families.

Keywords: home environment, Latino, obesity, parents, healthy eating, physical activity

Procedia PDF Downloads 273

Authors: Forhana Rahman Noor, Shafia Jannat Khanam

Abstract:

A girl’s schooling is disrupted by the very act of marriage which requires her to move away from home and her school area to live with her husband’s family, according to custom and practice. Once in her new home, her husband or her in-laws decide her continuation of schooling. A plethora of research has confirmed the inter-relationship between education and age at marriage of girls. The primary data was collected from both urban and rural area in Bangladesh. The study revealed that mean age at marriage for girls was 15.69 years, as a whole and it was lower (15.21 years) in the rural area than that of the urban area (17.13 years). These readings confirm early marriage still exists. The most important determinant of age at marriage was found as low education level of the girls. The bi-variate analysis of this study discovered the relationship or association between education and age at marriage. The study also found the education level of husbands of girls has a significant effect on age at marriage of a girl.

Keywords: education, girl, age at marriage, correlate, Bangladesh

Procedia PDF Downloads 320

Authors: Song Qingfeng

Abstract:

This research aims to seek the relationship between social media usage and overtourism from the perspective of tourists based on the theory of Maslow’s hierarchy needs. A questionnaire is formulated to collect data from 400 tourists who have visited the Hangzhou city in China in the last 12 months. Structural Equation Model (SEM) is employed to analysis data. The finding is that social media usage aggravates overtourism. Specifically, social media is used by tourists to information-seeking, entertainment, self-presentation, and socialization for traveling. These roles of social media would evoke the traveling intention to a specific destination at a certain time, which further influences the tourist flow. When the tourist flow concentrate, the overtourism would be aggravated. This study contributes to the destination managers to deep-understand the cause-effect relationship between social media and overtourism in order to address this problem.

Keywords: social media, overtourism, tourist flow, SEM, Maslow’s hierarchy of needs, Hangzhou

Procedia PDF Downloads 128

Authors: Ghazi Faisal Najmuldeen, Wahida Amat Fadzila

Abstract:

The aim of this study is to investigate physical and mechanical properties of experimental particleboards manufactured from mixing the oil palm fronds particles with empty fruit bunch fibers. Variables were two blending ratios (100:0 and 70:30), press temperature (160°C and 180°C) and press time (180 and 300 s). Experimental boards with a target density of 750 kg m-3 were manufactured from these two particles and fibers blended with urea formaldehyde resin and compressed into targeted thickness. The effect of these manufacturing conditions on bending strength, internal bonding, water absorption and thickness swelling were determined. From this research, it can be concluded that hybridization of fibers with fronds particles improved some properties of particleboard. Empty fruit bunch fibers and fronds particleboard showed better modulus of rupture and internal bonding than fronds particleboards.

Keywords: oil palm fronds, empty fruit bunch, particleboards, chemistry, environment

Procedia PDF Downloads 311