Search results for: material profiles

Authors: Moaz H. Ali, Ahmed H. Al-Saadi

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Most of the materials used in the industry of aero-engine components generally consist of titanium alloys. Advanced materials, because of their excellent combination of high specific strength, lightweight, and general corrosion resistance. In fact, chemical wear resistance of aero-engine alloy provide a serious challenge for cutting tool material during the machining process. The reduction in cutting temperature distributions leads to an increase in tool life and a decrease in wear rate. Hence, the chip morphology and segmentation play a predominant role in determining machinability and tool wear during the machining process. The result of low thermal conductivity and diffusivity of this alloy in the concentration of high temperatures at the tool-work-piece and tool-chip interface. Consequently, the chip morphology is very important in the study of machinability of metals as well as the study of cutting tool wear. Otherwise, the result will be accelerating tool wear, increasing manufacturing cost and time consuming.

Keywords: machinability, titanium alloy (ti-6al-4v), chip formation, milling process

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Authors: Sarka Keprdova, Jiri Bydzovsky

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This article describes to what extent the addition of energy by-products into the structures of the technical hemp filling materials influence their properties. The article focuses on the changes in physical-mechanical and thermal technical properties of materials after the addition of ash or FBC ash or slag in the binding component of material. Technical hemp filling materials are made of technical hemp shives bonded by the mixture of cement and dry hydrate lime. They are applicable as fillers of vertical or horizontal structures or roofs. The research used eight types of energy by-products of power or heating plants in the Czech Republic. Secondary energy products were dispensed in three different percentage ratios as a replacement of cement in the binding component. Density, compressive strength and determination of the coefficient of thermal conductivity after 28, 60 and 90 days of curing in a laboratory environment were determined and subsequently evaluated on the specimens produced.

Keywords: ash, binder, cement, energy by-product, FBC ash (fluidized bed combustion ash), filling materials, shives, slag, technical hemp

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Authors: Saowaluck Ukrisdawithid

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The thermal conductivity of thermal insulation materials are measured by Heat Flow Meter (HFM) apparatus. The components of uncertainty are complex and difficult on routine measurement by modelling approach. In this study, uncertainty of thermal conductivity measurement was estimated by single laboratory validation approach. The within-laboratory reproducibility was 1.1%. The standard uncertainty of method and laboratory bias by using SRM1453 expanded polystyrene board was dominant at 1.4%. However, it was assessed that there was no significant bias. For sample measurement, the sources of uncertainty were repeatability, density of sample and thermal conductivity resolution of HFM. From this approach to sample measurements, the combined uncertainty was calculated. In summary, the thermal conductivity of sample, polystyrene foam, was reported as 0.03367 W/m·K ± 3.5% (k = 2) at mean temperature 23.5 °C. The single laboratory validation approach is simple key of routine testing laboratory for estimation uncertainty of thermal conductivity measurement by using HFM, according to ISO/IEC 17025-2017 requirements. These are meaningful for laboratory competent improvement, quality control on products, and conformity assessment.

Keywords: single laboratory validation approach, within-laboratory reproducibility, method and laboratory bias, certified reference material

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Authors: Yasser M. Abd-elrhman, Mohamed A. Gepreel, Kiochi Nakamura, Ahmed Abd El-Moneim, Sengo Kobayashi, Mervat M. Ibrahim

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Titanium alloys are known as highly bio compatible metallic materials due to their high strength, low elastic modulus, and high corrosion resistance in biological media. Besides other important material features, the corrosion parameters and corrosion products are responsible for limiting the biological and chemical bio compatibility of metallic materials that produce undesirable reactions in implant-adjacent and/or more distant tissues. Electrochemical corrosion behaviors of novel beta titanium alloys, Ti-4.7Mo-4.5Fe, Ti-3Mo-0.5Fe, and Ti-2Mo-0.5Fe were characterized in naturally aerated Ringer’s solution at room temperature compared with common used biomedical titanium alloy, Ti-6Al-4V. The corrosion resistance of titanium alloys were investigated through open circuit potential (OCP), potentiodynamic polarization measurements and optical microscope (OM). A high corrosion resistance was obtained for all alloys due to the stable passive film formed on their surfaces. The new present alloys are promising metallic biomaterials for the future, owing to their very low elastic modulus and good corrosion resistance capabilities.

Keywords: titanium alloys, corrosion resistance, Ringer’s solution, electrochemical corrosion

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Authors: Ahmad Al Aboudi

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The Department of Archaeology at King Saud University conduct a long Term excavations since 2004 at the archaeological site of (Qurh) in Al-Ula area. The history of the site goes back to the eighth century AD. The main aim of the excavations is the training of the students on the archaeological field work associated with the scientific skills of exploring, surveying, classifying, documentations and other necessary in the field archaeology. During the 12th Season of Excavations, an area of 20 × 40 m2 of the site was excavated. The depth of the excavating the site was reached to 2-3 m. Many of the architectural features of a residential area in the northern part of the site were excavated this season. Circular walls made of mud-brick and a brick column drums and tiles made of clay were revealed this season. Additionally, lots of findings such as Gemstones, jars, ceramic plates, metal, glass, and fabric, as well as some jewelers and coins were discovered. This paper will deal with the main results of this field project including the architectural features and phenomena and their interpretations, the classification of excavated material culture remains and stratigraphy.

Keywords: Islamic architecture, Islamic art, excavations, early Islamic city

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Authors: Edwin Cartledge, Jack Clark, Mazaher Molaei-Chalchooghi

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The mixing in the crystallization step of active pharmaceutical ingredient manufacturers was studied via advanced modeling tools to enable a successful scale-up. A virtual representation of the vessel was created, and computational fluid dynamics were used to simulate multiphase flow and, thus, the mixing environment within this vessel. The study identified a significant dead zone in the vessel underneath the impeller and found that increasing the impeller speed and power did not improve the mixing. A series of sensitivity analyses found that to improve mixing, the vessel had to be redesigned, and found that optimal mixing could be obtained by adding two extra cylindrical baffles. The same two baffles from the simulated environment were then constructed and added to the process vessel. By identifying these potential issues before starting the manufacture and modifying the vessel to ensure good mixing, this study mitigated a failed crystallization and potential batch disposal, which could have resulted in a significant loss of high-value material.

Keywords: active pharmaceutical ingredient, baffles, computational fluid dynamics, mixing, modelling

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Authors: Sanita Rubene, Martins Vilnitis, Juris Noviks

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Aerated concrete is a load bearing construction material, which has high heat insulation parameters. Walls can be erected from aerated concrete masonry constructions and in perfect circumstances additional heat insulation is not required. The most common problem in aerated concrete heat insulation properties is the humidity distribution throughout the cross section of the masonry elements as well as proper and conducted drying process of the aerated concrete construction because only dry aerated concrete masonry constructions can reach high heat insulation parameters. In order to monitor drying process of the masonry and detect humidity distribution throughout the cross section of aerated concrete masonry construction application of electrical impedance spectrometry is applied. Further test results and methodology of this non-destructive testing method is described in this paper.

Keywords: aerated concrete, electrical impedance spectrometry, humidity distribution, non-destructive testing

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Authors: Minto Rattan, Tania Bose, Neeraj Chamoli

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The present paper investigates the effect of linear thermal gradient on the steady-state creep behavior of rotating isotropic disc using threshold stress based Sherby’s creep law. The composite discs made of aluminum matrix reinforced with silicon carbide particulate has been taken for analysis. The stress and strain rate distributions have been calculated for discs rotating at linear thermal gradation using von Mises’ yield criterion. The material parameters have been estimated by regression fit of the available experimental data. The results are displayed and compared graphically in designer friendly format for the above said temperature profile with the disc operating under uniform temperature profile. It is observed that radial and tangential stresses show minor variation and the strain rates vary significantly in the presence of thermal gradation as compared to disc having uniform temperature.

Keywords: creep, isotropic, steady-state, thermal gradient

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Authors: B. Yaman, G. Acikbas, N. Calis Acikbas

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Epoxy based materials have advantages in tribological applications due to their unique properties such as light weight, self-lubrication capacity and wear resistance. On the other hand, their usage is often limited by their low load bearing capacity and low thermal conductivity values. In this study, it is aimed to improve tribological and also mechanical properties of epoxy by reinforcing with ceramic based porcelain waste. It is well-known that the reuse or recycling of waste materials leads to reduction in production costs, ease of manufacturing, saving energy, etc. From this perspective, epoxy and epoxy matrix composites containing 60wt% porcelain waste with different particle size in the range of below 90µm and 150-250µm were fabricated, and the effect of filler particle size on the mechanical and tribological properties was investigated. The microstructural characterization was carried out by scanning electron microscopy (SEM), and phase analysis was determined by X-ray diffraction (XRD). The Archimedes principle was used to measure the density and porosity of the samples. The hardness values were measured using Shore-D hardness, and bending tests were performed. Microstructural investigations indicated that porcelain particles were homogeneously distributed and no agglomerations were encountered in the epoxy resin. Mechanical test results showed that the hardness and bending strength were increased with increasing particle size related to low porosity content and well embedding to the matrix. Tribological behavior of these composites was evaluated in terms of friction, wear rates and wear mechanisms by ball-on-disk contact with dry and rotational sliding at room temperature against WC ball with a diameter of 3mm. Wear tests were carried out at room temperature (23–25°C) with a humidity of 40 ± 5% under dry-sliding conditions. The contact radius of cycles was set to 5 mm at linear speed of 30 cm/s for the geometry used in this study. In all the experiments, 3N of constant test load was applied at a frequency of 8 Hz and prolonged to 400m wear distance. The friction coefficient of samples was recorded online by the variation in the tangential force. The steady-state CoFs were changed in between 0,29-0,32. The dimensions of the wear tracks (depth and width) were measured as two-dimensional profiles by a stylus profilometer. The wear volumes were calculated by integrating these 2D surface areas over the diameter. Specific wear rates were computed by dividing the wear volume by the applied load and sliding distance. According to the experimental results, the use of porcelain waste in the fabrication of epoxy resin composites can be suggested to be potential materials due to allowing improved mechanical and tribological properties and also providing reduction in production cost.

Keywords: epoxy composites, mechanical properties, porcelain waste, tribological properties

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Authors: Y. Z. Gad

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Disorders of Sex Development (DSD) are defined as congenital conditions in which development of chromosomal, gonadal or anatomical sex is atypical. The DSD are relatively prevalent in Egypt. In spite of that, the relative rarity of the individual disease types or their molecular pathologies frequently resulted in reporting on single or few cases. This augmented the challenging nature of phenotype-genotype correlation in this disease group and its utilization in the management of such medical emergency. Through critical assessment of the published DSD reports, the current review aims at analyzing the clinical characteristics of the various DSD forms in relation to the underlying molecular pathologies. A systematic literature search was done in Pubmed, using relevant keywords (Egypt versus DSD, genital ambiguity or ambiguous genitalia, the old terms of 'intersex, hermaphroditism and pseudohermaphroditism', and a list of the DSD entities and their related genes). The search yielded 24 reports of molecular data in Egyptian patients presenting with ambiguous genitalia. However, only 21 publications fulfilled the criteria of inclusion of detailed clinical descriptions and definitive molecular diagnoses of individual patients. Curation of the data yielded a total of 53 cases that were ascertained from 40 families. Fifty-one patients present with ambiguous genitalia only while 2 had multiple congenital anomalies. Parental consanguinity was noted in 60% of cases. Sex of rearing at initial presentation was female in 75% and 60% in 46,XY and 46,XX DSD cases, respectively. The external genital phenotype in 2/3 of the 46,XY DSD cases showed moderate undermasculinization [Quigley scores 3 & 4] and 1/3 had severe presentations [scores 5 & 6]. For 46,XX subjects, 1 had severe virilization of the external genitalia while 8 had moderate phenotype. Hormonal data were inconclusive or contradictory to final diagnosis in a forth of cases. Collectively, 31 families [31/40, 77.5%] with 46,XY DSD had molecular defects in the genes, 5 alpha reductase 2 (SRD5A2) [12/31], 17 beta-hydroxysteroid dehydrogenase 3 [8/31], androgen receptor [7/31], Steroidogenic factor 1 [2/31], luteinizing hormone receptor [1/31], and fibroblast growth factor receptor 1 [1/31]. In a multiethnic study, 9 families afflicted with 46,XX DSD due to 11 beta hydroxylase (CYP11B1) deficiency were documented. Two recurrent mutations, G34R and N160D, in SRD5A2 were present, respectively, in 42 and 17% of cases. Similarly, 4 recurrent mutations resulted in 89% of the CYP11B1 presentations. In conclusion, this analysis highlights the importance of autosomal recessive inheritance and inbreeding among DSD presentations, the importance of founder effect in at least 2 disorders, the difficulties in relating the genotype with the indeterminate genital phenotype, the under-reporting of some DSD subtypes, and the notion that the reported mutational profiles among Egyptian DSD cases are relatively different from those reported in other ethnic groups.

Keywords: disorders of sex development, genital ambiguity, mutation, molecular diagnosis, Egypt

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Authors: Kamolvara Sirisuksakulchai, Soamwadee Chaianansutcharit, Kazunori Sato

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Solid Oxide Fuel Cells (SOFCs) have been considered as one of the most efficient large unit power generators for household and industrial applications. The efficiency of an electronic cell depends mainly on the electrochemical reactions in the anode. The development of anode materials has been intensely studied to achieve higher kinetic rates of redox reactions and lower internal resistance. Recent studies have introduced an efficient cermet (ceramic-metallic) material for its ability in fuel oxidation and oxide conduction. This could expand the reactive site, also known as the triple-phase boundary (TPB), thus increasing the overall performance. In this study, a bimetallic catalyst Ni₀.₇₅Co₀.₂₅Oₓ was combined with Gd₀.₁Ce₀.₉O₁.₉₅ (GDC) to be used as a cermet anode (NiCo-GDC) for an anode-supported type SOFC. The synthesis of Ni₀.₇₅Co₀.₂₅Oₓ was carried out by ball milling NiO and Co3O4 powders in ethanol and calcined at 1000 °C. The Gd₀.₁Ce₀.₉O₁.₉₅ was prepared by a urea co-precipitation method. Precursors of Gd(NO₃)₃·6H₂O and Ce(NO₃)₃·6H₂O were dissolved in distilled water with the addition of urea and were heated subsequently. The heated mixture product was filtered and rinsed thoroughly, then dried and calcined at 800 °C and 1500 °C, respectively. The two powders were combined followed by pelletization and sintering at 1100 °C to form an anode support layer. The fabrications of an electrolyte layer and cathode layer were conducted. The electrochemical performance in H₂ was measured from 800 °C to 600 °C while for CH₄ was from 750 °C to 600 °C. The maximum power density at 750 °C in H₂ was 13% higher than in CH₄. The difference in performance was due to higher polarization resistances confirmed by the impedance spectra. According to the standard enthalpy, the dissociation energy of C-H bonds in CH₄ is slightly higher than the H-H bond H₂. The dissociation of CH₄ could be the cause of resistance within the anode material. The results from lower temperatures showed a descending trend of power density in relevance to the increased polarization resistance. This was due to lowering conductivity when the temperature decreases. The long-term stability was measured at 750 °C in CH₄ monitoring at 12-hour intervals. The maximum power density tends to increase gradually with time while the resistances were maintained. This suggests the enhanced stability from charge transfer activities in doped ceria due to the transition of Ce⁴⁺ ↔ Ce³⁺ at low oxygen partial pressure and high-temperature atmosphere. However, the power density started to drop after 60 h, and the cell potential also dropped from 0.3249 V to 0.2850 V. These phenomena was confirmed by a shifted impedance spectra indicating a higher ohmic resistance. The observation by FESEM and EDX-mapping suggests the degradation due to mass transport of ions in the electrolyte while the anode microstructure was still maintained. In summary, the electrochemical test and stability test for 60 h was achieved by NiCo-GDC cermet anode. Coke deposition was not detected after operation in CH₄, hence this confirms the superior properties of the bimetallic cermet anode over typical Ni-GDC.

Keywords: bimetallic catalyst, ceria-based SOFCs, methane oxidation, solid oxide fuel cell

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Authors: B. M. Y. I. Basnayake, G. G. T. Nisansala, P. I. J. B. Wijewickrama, U. S. Weerathunga, K. W. M. Y. D. Gunasekara, N. K. Jayasekera, A. W. Kalupahana, R. S. Kalupahana, A. Silva- Fletcher, K. S. A. Kottawatta

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Antimicrobial resistance (AMR) has attracted significant attention worldwide as an emerging threat to public health. Understanding the role of livestock and wildlife with the shared environment in the maintenance and transmission of AMR is of utmost importance due to its interactions with humans for combating the issue in one health approach. This study aims to investigate the extent of AMR distribution among wild animals, livestock, and environment cohabiting in a rural ecosystem in Sri Lanka: Hambegamuwa. One square km area at Hambegamuwa was mapped using GPS as the sampling area. The study was conducted for a period of five months from November 2020. Voided fecal samples were collected from 130 wild animals, 123 livestock: buffalo, cattle, chicken, and turkey, with 36 soil and 30 water samples associated with livestock and wildlife. From the samples, Escherichia coli (E. coli) was isolated, and their AMR profiles were investigated for 12 antimicrobials using the disk diffusion method following the CLSI standard. Seventy percent (91/130) of wild animals, 93% (115/123) of livestock, 89% (32/36) of soil, and 63% (19/30) of water samples were positive for E. coli. Maximum of two E. coli from each sample to a total of 467 were tested for the sensitivity of which 157, 208, 62, and 40 were from wild animals, livestock, soil, and water, respectively. The highest resistance in E. coli from livestock (13.9%) and wild animals (13.3%) was for ampicillin, followed by streptomycin. Apart from that, E. coli from livestock and wild animals revealed resistance mainly against tetracycline, cefotaxime, trimethoprim/ sulfamethoxazole, and nalidixic acid at levels less than 10%. Ten cefotaxime resistant E. coli were reported from wild animals, including four elephants, two land monitors, a pigeon, a spotted dove, and a monkey which was a significant finding. E. coli from soil samples reflected resistance primarily against ampicillin, streptomycin, and tetracycline at levels less than in livestock/wildlife. Two water samples had cefotaxime resistant E. coli as the only resistant isolates out of 30 water samples tested. Of the total E. coli isolates, 6.4% (30/467) was multi-drug resistant (MDR) which included 18, 9, and 3 isolates from livestock, wild animals, and soil, respectively. Among 18 livestock MDRs, the highest (13/ 18) was from poultry. Nine wild animal MDRs were from spotted dove, pigeon, land monitor, and elephant. Based on CLSI standard criteria, 60 E. coli isolates, of which 40, 16, and 4 from livestock, wild animal, and environment, respectively, were screened for Extended Spectrum β-Lactamase (ESBL) producers. Despite being a rural ecosystem, AMR and MDR are prevalent even at low levels. E. coli from livestock, wild animals, and the environment reflected a similar spectrum of AMR where ampicillin, streptomycin, tetracycline, and cefotaxime being the predominant antimicrobials of resistance. Wild animals may have acquired AMR via direct contact with livestock or via the environment, as antimicrobials are rarely used in wild animals. A source attribution study including the effects of the natural environment to study AMR can be proposed as this less contaminated rural ecosystem alarms the presence of AMR.

Keywords: AMR, Escherichia coli, livestock, wildlife

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Authors: Talbi Mohammed, Oustous Aziz, Ben Messaoud Mounir, Sebihi Rajaa, Khalis Mohammed

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Background: Breast cancer is the leading cause of death for women around the world. Screening mammography is the reference examination, due to its sensitivity for detecting small lesions and micro-calcifications. Therefore, it is essential to ensure quality mammographic examinations with the most optimal dose. These conditions depend on the choice of exposure parameters. Clinically, practices must be evaluated in order to determine the most appropriate exposure parameters. Material and Methods: We performed our measurements on a mobile mammography unit (PLANMED Sofie-classic.) in Morocco. A solid dosimeter (AGMS Radcal) and a MTM 100 phantom allow to quantify the delivered dose and the image quality. For image quality assessment, scores are defined by the rate of visible inserts (MTM 100 phantom), obtained and compared for each acquisition. Results: The results show that the parameters of the mammography unit on which we have made our measurements can be improved in order to offer a better compromise between image quality and breast dose. The last one can be reduced up from 13.27% to 22.16%, while preserving comparable image quality.

Keywords: Mammography, Breast Dose, Image Quality, Phantom

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Authors: Suzannah Sharif, Aznie Aida Ahmad, Maznah Ismail

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Cocoa bean is the raw material for products such as cocoa powder and chocolate. Cocoa bean contains polyphenol which has been shown in several clinical studies to confer beneficial health effects. However studies showed that cocoa polyphenol absorption in the human intestinal tracts are very low. Therefore nanoemulsion may be one way to increase the bioavailability of cocoa polyphenol. This study aim to characterize nanoemulsion incorporating crude cocoa polyphenol produced using high energy technique. Cocoa polyphenol was extracted from fresh freeze-dried cocoa beans from Malaysia. The particle distribution, particle size, and zeta potential were determined. The emulsion was also analysed using transmission electron microscope to visualize the particles. Solubilization study was conducted by titrating the nanoemulsion into distilled water or 1% surfactant solution. Result showed that the nanoemulsion contains particle which have narrow size distribution. The particles size average at 112nm with zeta potential of -45mV. The nanoemulsions behave differently in distilled water and surfactant solution.

Keywords: cocoa, nanoemulsion, cocoa polyphenol, solubilisation study

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Authors: W. Intagun, T. Khamdaeng, P. Prom-ngarm, N. Panyoyai

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Biochar has been used as a soil amendment since it has high porous structure and has proper nutrients and chemical properties for plants. Product yields produced from biochar kiln are dependent on process parameters and kiln types used. The objective of this research is to investigate the effect of core puncture diameter on biochar kiln efficiency, i.e., yields of biochar and produced gas. Corncobs were used as raw material to produce biochar. Briquettes from agricultural wastes were used as fuel. Each treatment was performed by changing the core puncture diameter. From the experiment, it is revealed that the yield of biochar at the core puncture diameter of 3.18 mm, 4.76 mm, and 6.35 mm was 10.62 wt. %, 24.12 wt. %, and 12.24 wt. %, of total solid yields, respectively. The yield of produced gas increased with increasing the core puncture diameter. The maximum percentage by weight of the yield of produced gas was 81.53 wt. % which was found at the core puncture diameter of 6.35 mm. The core puncture diameter was furthermore found to affect the temperature distribution inside the kiln and its thermal efficiency. In conclusion, the high efficient biochar kiln can be designed and constructed by using the proper core puncture diameter.

Keywords: anila stove, bio-char, soil conditioning materials, temperature distribution

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Authors: M. Yusuf Ansari, Asad Abbas

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Proton exchange membrane (PEM) fuel cell is a very efficient and promising energy conversion device. Although Nafion® is considered as benchmark materials for membrane used in PEM fuel cell, it has limitations that restrict its uses. Alternative materials for the membrane is always a challenging field for researchers. Sulfonated poly(ether ether ketone) (SPEEK) is one of the promising material for membrane due to its chemical and mechanical stability and lower cost. In this work, SPEEK is synthesized, and property booster such as silica nanoparticles and polyvinyl alcohol (PVA) are also added to analyse changes in properties such as water uptake, IEC, and conductivity. It has been found that adding PVA support high water uptake and proton conductivity but at large amount of PVA reduces the proton conductivity due to very high water uptake. Adding silica enhances water uptake and proton conductivity.

Keywords: PEM Membrane, sulfonated poly (ether ether ketone) (SPEEK), silica fumes (SiO2), polyvinyl alcohol (PVA)

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Authors: Khalid Ahmed Eldwaib

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In this study, Al-Mg alloy 5052 was used as the testing material. Corrosion fatigue life was studied for the alloy in 3.5% NaCl (pH=1, 3, 5, 7, 9, and 11), and 3.5% NaCl (pH=1) with inhibitors. The compound inhibitors were composed mainly of phosphate (PO4³-), adding a certain proportion of other nontoxic inhibitors so as to select alternatives to environmentally hazardous chromate (Cr2O7²-). The inhibitors were sodium dichromate Na2Cr2O7, sodium phosphate Na3PO4, sodium molybdate Na2MoO4, and sodium citrate Na3C6H5O7. The total amount of inhibiting pigments was at different concentrations (250,500,750, and 1000 ppm) in the solutions. Corrosion fatigue behavior was studied by using plane-bending corrosion fatigue machine with stress ratio R=0.5 and under the constant frequency of 13.3 Hz. Results show that in 3.5% NaCl the highest fatigue life (number of cycles to failure Nf) is obtained at pH=5 where the oxide film on aluminum has very low solubility, and the lowest number of cycles is obtained at pH=1, where the media is too aggressive (extremely acidic). When the concentration of inhibitor increases the cycles to failure increase. The surface morphology and fracture section of the specimens had been characterized through scanning electron microscope (SEM).

Keywords: Al-Mg alloy 5052, corrosion, fatigue, inhibitors

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Authors: G. Rajyalakhmi, C. Karthik, Gerson Desouza, Rimmie Duraisamy

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In this present work, metal matrix composites with combination of aluminium with (Sic/Al2O3) were fabricated using stir casting technique. The objective of the present work is to optimize the process parameters of Wire Electric Discharge Machining (WEDM) composites. Pulse ON Time, Pulse OFF Time, wire feed and sensitivity are considered as input process parameters with responses Material Removal Rate (MRR), Surface Roughness (SR) for optimization of WEDM process. Taguchi L18 Orthogonal Array (OA) is used for experimentation. Grey Relational Analysis (GRA) is coupled with Taguchi technique for multiple process parameters optimization. ANOVA (Analysis of Variance) is used for finding the impact of process parameters individually. Finally confirmation experiments were carried out to validate the predicted results.

Keywords: parametric optimization, particulate reinforced metal matrix composites, Taguchi-grey relational analysis, WEDM

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Authors: Leila Ayat, Afak Meftah

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Amorphous-silicon alloys have great promise as low cost solar cell materials. They have excellent photo-conductivity and high optical absorption to sunlight. Now PIN a-Si:H based solar cells are widely used in power generation modules. However, to improve the performance of these cells further, a better fundamental under-standing of the factors limiting cell performance in the homo junction PIN structure is necessary. In this paper we discuss the sensitivity of light J-V characteristics to various device and material parameters in PIN homo junction solar cells. This work is a numerical simulation of the output parameters of a PIN a-Si:H solar cell under AM1.5 spectrum. These parameters are the short circuit current (Jsc), the open circuit voltage (Voc), the fill factor (FF), the conversion efficiency. The simulation was performed with SCAPS-1D software version 3.3 developed at ELIS in Belgium by Marc Burgelman et al. The obtained results are in agreement with experiment. In addition, the effect of the thickness, doping density, capture cross sections of the gap states and the band microscopic mobilities on the output parameters of the cell are also presented.

Keywords: amorphous silicon p-i-n junctions, thin film, solar cells, sensitivity

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Authors: Shaohua Li, Aihua Zhang, Kelly Zatopek, Saba Parvez, Andrew F. Gardner, Ivan R. Corrêa Jr., Christopher J. Noren, Ming-Qun Xu

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Covalent immobilization of enzymes on solid supports is an alternative approach to biocatalysis with the added benefits of simple enzyme removal, improved stability, and adaptability to automation and high-throughput applications. Nevertheless, immobilized enzymes generally suffer from reduced activities compared to their soluble counterparts. One major factor leading to activity loss is the intrinsic hydrophobic property of the supporting material surface, which could result in the conformational change/confinement of enzymes. We report a strategy of utilizing flexible poly (ethylene oxide) (PEO) moieties as to improve the surface hydrophilicity of solid supports used for enzyme immobilization. DNA modifying enzymes were covalently conjugated to PEO-coated magnetic-beads. Kinetics studies proved that the activities of the covalently-immobilized DNA modifying enzymes were greatly enhanced by the PEO modification on the bead surface.

Keywords: immobilized enzymes, biocatalysis, poly(ethylene oxide), surface modification

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Authors: Shah Abbas

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Rheumatoid arthritis is a systemic, inflammatory autoimmune disease, affecting an overall 1% of the global population. Despite being tremendous efforts by scientists, early diagnosis of RA still has not been achieved. In the current study, a Graphene oxide (GO) based electrochemical sensor has been developed for early diagnosis of RA through Cyclic voltammetry. Chitosan (CHI), a CPnatural polymer has also been incorporated along with GO in order to enhance the biocompatibility and functionalization potential of the biosensor. CCPs are known antigens for Anti Citrullinated Peptide Antibodies (ACPAs) which can be detected in serum even 14 years before the appearance of symptoms, thus they are believed to be an ideal target for the early diagnosis of RA. This study has yielded some promising results regarding the binding and detection of ACPAs through changes in the electrochemical properties of biosensing material. The cyclic voltammogram of this biosensor reflects the binding of ACPAs to the biosensor surface, due to its shifts observed in the current flow (cathodic current) as compared to the when no ACPAs bind as it is absent in RA negative patients.

Keywords: rheumatoid arthritis, peptide sensor, graphene oxide, anti citrullinated peptide antibodies, cyclic voltammetry

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Authors: Heloise Sasso Teixeira, Talita Szlapak Franco, Thais Helena Sydenstricker Flores-Sahagun, Milton Vazquez Lepe, Graciela Bolzon Muñiz

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Due to the need to reduce the consumption of materials produced from non-renewable sources, the search for new raw materials of natural origin is growing. In this regard, lignocellulosic fibers have great potential. Ceiba sp fibers are found in the fruit of the tree of the same name and have characteristics that differ from other natural fibers. Ceiba fibers are very light, have a high cellulose content, and are hydrophobic due to the presence of waxes on their surface. In this study, Ceiba fiber was used as raw material to obtain cellulose nanofibers (CNF), with the potential to be used in polymeric matrices. Due to the characteristics of this fiber, no chemical pretreatment was necessary before the mechanical defibrilation process in a colloidal mill, obtaining sustainable nanocellulose. The CNFs were characterized by Fourier infrared (FTIR), differential scanning calorimetry (DSC), analysis of the rmogravimetic (TGA), scanning electron microscopy (SEM), transmission electron microscopy, and X-ray photoelectron spectroscopy (XPS).

Keywords: cellulose nanofibers, nanocellulose, fibers, Brazilian fIbers, lignocellulosic, characterization

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Authors: Richard, Iyan Subiyanto, Chairul Hudaya

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Activated carbon has been playing a significant role for many applications, especially in energy storage devices. However, commercially activated carbons generally require complicated processes and high production costs. Therefore, in this study, an activated carbon originating from green coke waste, that is economically affordable will be used as a carbon source. To synthesize activated carbon, KOH as an activator was employed with variation of C:KOH in ratio of 1:2, 1:3, 1:4, and 1:5, respectively, with an activation temperature of 700°C. The characterizations of activated carbon are obtained from Scanning Electron Microscopy, Energy Dispersive X-Ray, Raman Spectroscopy, and Brunauer-Emmett-Teller. The optimal activated carbon sample with specific surface area of 2,024 m²/g with high carbon content ( > 80%) supported by the high porosity carbon image obtained by SEM was prepared at C:KOH ratio of 1:4. The result shows that the synthesized activated carbon would be an ideal choice for energy storage device applications. Therefore, this study is expected to reduce the costs of activated carbon production by expanding the utilization of petroleum waste.

Keywords: activated carbon, energy storage material, green coke, specific surface area

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Authors: Hamidreza Heidari, Abdollah Malmir Nasab

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In this paper, the energy equations of a two-link flexible manipulator were extracted using the Euler-Bernoulli beam hypotheses. Applying Assumed mode and considering some finite degrees of freedom, we could obtain dynamic motions of each manipulator using Euler-Lagrange equations. Using its claws, the robots can carry a certain load with the ached control of vibrations for robot flexible links during the travelling path using the piezoceramics transducer; dynamic load carrying capacity increase. The traveling path of flexible robot claw has been taken from that of equivalent rigid manipulator and coupled; therefore to avoid the role of Euler-Bernoulli beam assumptions and linear strains, material and physical characteristics selection of robot cause deflection of link ends not exceed 5% of link length. To do so, the maximum load carrying capacity of robot is calculated at the horizontal plan. The increasing of robot load carrying capacity with vibration control is 53%.

Keywords: flexible link, DLCC, active control vibration, assumed mode method

Procedia PDF Downloads 381

Authors: Nasrine Olson

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With over 70,000 scholarly publications on the topic of biosensors, an overview of the field has become a challenge. To facilitate, there are currently over 700 expert-reviews of publications on biosensors and related topics. This study focuses on these review papers in order to provide a Meta-Review of the area. This paper provides a statistical analysis and overview of biosensor-related review papers. Comprehensive searches are conducted in the Web of Science, and PubMed databases and the resulting empirical material are analyzed using bibliometric methods and tools. The study finds that the biosensor-related review papers can be categorized in five related subgroups, broadly denoted by (i) properties of materials and particles, (ii) analysis and indicators, (iii) diagnostics, (iv) pollutant and analytical devices, and (v) treatment/ application. For an easy and clear access to the findings visualization of clusters and networks of connections are presented. The study includes a temporal dimension and identifies the trends over the years with an emphasis on the most recent developments. This paper provides useful insights for those who wish to form a better understanding of the research trends in the area of biosensors.

Keywords: bibliometrics, biosensors, meta-review, statistical analysis, trends visualization

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Authors: Elena B. Cherepetskaya, Alexander A.Karabutov, Vladimir A. Makarov, Elena A. Mironova, Ivan A. Shibaev

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In our study, the object of laser ultrasonic testing was plane-parallel plate of shungit (length 41 mm, width 31 mm, height 15 mm, medium exchange density 2247 kg/m3). We used laser-ultrasonic defectoscope with wideband opto-acoustic transducer in our investigation of the velocities of longitudinal and shear elastic ultrasound waves. The duration of arising elastic pulses was less than 100 ns. Under known material thickness, the values of the velocities were determined by the time delay of the pulses reflected from the bottom surface of the sample with respect to reference pulses. The accuracy of measurement was 0.3% in the case of longitudinal wave velocity and 0.5% in the case of shear wave velocity (scanning pitch along the surface was 2 mm). On the base of found velocities of elastic waves, local elastic moduli of shungit (Young modulus, shear modulus and Poisson's ratio) were uniquely determined.

Keywords: laser ultrasonic testing , local elastic moduli, shear wave velocity, shungit

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Authors: Mustafa M. Donma, Orkide Donma

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Spexin, expressed in central nervous system, has attracted much interest in feeding behavior, obesity, diabetes, energy metabolism and cardiovascular functions. Fetuin A is known as negative acute phase reactant synthesized in the liver. So far, it has become a major concern of many studies in numerous clinical states. The relationship between the concentrations of spexin as well as fetuin A and the risk for cardiovascular diseases (CVDs) were also investigated. Eosinophils, suggested to be associated with the development of CVDs, are introduced as early indicators of cardiometabolic complications. Patients with elevated platelet count, associated with hypercoagulable state in the body, are also more liable to CVDs. In this study, the aim is to examine the profiles of spexin and fetuin A concomitant with the course of variations detected in eosinophil as well as platelet counts in morbid obese children. Thirty-four children with normal-body mass index (N-BMI) and fifty-one morbid obese (MO) children participated in the study. Written-informed consent forms were obtained prior to the study. Institutional ethics committee approved the study protocol. Age- and sex-adjusted BMI percentile tables prepared by World Health Organization were used to classify healthy and obese children. Mean age ± SEM of the children were 9.3 ± 0.6 years and 10.7 ± 0.5 years in N-BMI and MO groups, respectively. Anthropometric measurements of the children were taken. Body mass index values were calculated from weight and height values. Blood samples were obtained after an overnight fasting. Routine hematologic and biochemical tests were performed. Within this context, fasting blood glucose (FBG), insulin (INS), triglycerides (TRG), high density lipoprotein-cholesterol (HDL-C) concentrations were measured. Homeostatic model assessment for insulin resistance (HOMA-IR) values were calculated. Spexin and fetuin A levels were determined by enzyme-linked immunosorbent assay. Data were evaluated from the statistical point of view. Statistically significant differences were found between groups in terms of BMI, fat mass index, INS, HOMA-IR and HDL-C. In MO group, all parameters increased as HDL-C decreased. Elevated concentrations in MO group were detected in eosinophils (p<0.05) and platelets (p>0.05). Fetuin A levels decreased in MO group (p>0.05). However, decrease was statistically significant in spexin levels for this group (p<0.05). In conclusion, these results have suggested that increases in eosinophils and platelets exhibit behavior as cardiovascular risk factors. Decreased fetuin A behaved as a risk factor suitable to increased risk for cardiovascular problems associated with the severity of obesity. Along with increased eosinophils, increased platelets and decreased fetuin A, decreased spexin was the parameter, which reflects best its possible participation in the early development of CVD risk in MO children.

Keywords: cardiovascular diseases , eosinophils , fetuin A , pediatric morbid obesity , platelets , spexin

Procedia PDF Downloads 177

Authors: David F. Nettleton, Elodie Bugnicourt, Christian Wasiak, Alejandro Rosales

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In this presentation, preliminary results are given for the modeling and calibration of two different industrial winding MIMO (Multiple Input Multiple Output) processes using machine learning techniques. In contrast to previous approaches which have typically used ‘black-box’ linear statistical methods together with a definition of the mechanical behavior of the process, we use non-linear machine learning algorithms together with a ‘white-box’ rule induction technique to create a supervised model of the fitting error between the expected and real force measures. The final objective is to build a precise model of the winding process in order to control de-tension of the material being wound in the first case, and the friction of the material passing through the die, in the second case. Case 1, Tension Control of a Winding Process. A plastic web is unwound from a first reel, goes over a traction reel and is rewound on a third reel. The objectives are: (i) to train a model to predict the web tension and (ii) calibration to find the input values which result in a given tension. Case 2, Friction Force Control of a Micro-Pullwinding Process. A core+resin passes through a first die, then two winding units wind an outer layer around the core, and a final pass through a second die. The objectives are: (i) to train a model to predict the friction on die2; (ii) calibration to find the input values which result in a given friction on die2. Different machine learning approaches are tested to build models, Kernel Ridge Regression, Support Vector Regression (with a Radial Basis Function Kernel) and MPART (Rule Induction with continuous value as output). As a previous step, the MPART rule induction algorithm was used to build an explicative model of the error (the difference between expected and real friction on die2). The modeling of the error behavior using explicative rules is used to help improve the overall process model. Once the models are built, the inputs are calibrated by generating Gaussian random numbers for each input (taking into account its mean and standard deviation) and comparing the output to a target (desired) output until a closest fit is found. The results of empirical testing show that a high precision is obtained for the trained models and for the calibration process. The learning step is the slowest part of the process (max. 5 minutes for this data), but this can be done offline just once. The calibration step is much faster and in under one minute obtained a precision error of less than 1x10-3 for both outputs. To summarize, in the present work two processes have been modeled and calibrated. A fast processing time and high precision has been achieved, which can be further improved by using heuristics to guide the Gaussian calibration. Error behavior has been modeled to help improve the overall process understanding. This has relevance for the quick optimal set up of many different industrial processes which use a pull-winding type process to manufacture fibre reinforced plastic parts. Acknowledgements to the Openmind project which is funded by Horizon 2020 European Union funding for Research & Innovation, Grant Agreement number 680820

Keywords: data model, machine learning, industrial winding, calibration

Procedia PDF Downloads 228

Authors: Inigo Sanz-Pena, Shanika Arachchi, Dilani Dhammika, Sanjaya Mallikarachchi, Jeewantha S. Bandula, Alison H. McGregor, Nicolas Newell

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The use of orthotic braces for adolescent idiopathic scoliosis (AIS) patients is the most common non-surgical treatment to prevent deformity progression. The traditional method to create an orthotic brace involves casting the patient’s torso to obtain a representative geometry, which is then rectified by an orthotist to the desired geometry of the brace. Recent improvements in 3D scanning technologies, rectification software, CNC, and additive manufacturing processes have given the possibility to compliment, or in some cases, replace manual methods with digital approaches. However, the rectification process remains dependent on the orthotist’s skills. Therefore, the rectification process needs to be carefully characterized to ensure that braces designed through a digital workflow are as efficient as those created using a manual process. The aim of this study is to compare 3D scans of patients with AIS against 3D scans of both pre- and post-rectified casts that have been manually shaped by an orthotist. Six AIS patients were recruited from the Ragama Rehabilitation Clinic, Colombo, Sri Lanka. All patients were between 10 and 15 years old, were skeletally immature (Risser grade 0-3), and had Cobb angles between 20-45°. Seven spherical markers were placed at key anatomical locations on each patient’s torso and on the pre- and post-rectified molds so that distances could be reliably measured. 3D scans were obtained of 1) the patient’s torso and pelvis, 2) the patient’s pre-rectification plaster mold, and 3) the patient’s post-rectification plaster mold using a Structure Sensor Mark II 3D scanner (Occipital Inc., USA). 3D stick body models were created for each scan to represent the distances between anatomical landmarks. The 3D stick models were used to analyze the changes in position and orientation of the anatomical landmarks between scans using Blender open-source software. 3D Surface deviation maps represented volume differences between the scans using CloudCompare open-source software. The 3D stick body models showed changes in the position and orientation of thorax anatomical landmarks between the patient and the post-rectification scans for all patients. Anatomical landmark position and volume differences were seen between 3D scans of the patient’s torsos and the pre-rectified molds. Between the pre- and post-rectified molds, material removal was consistently seen on the anterior side of the thorax and the lateral areas below the ribcage. Volume differences were seen in areas where the orthotist planned to place pressure pads (usually at the trochanter on the side to which the lumbar curve was tilted (trochanter pad), at the lumbar apical vertebra (lumbar pad), on the rib connected to the apical vertebrae at the mid-axillary line (thoracic pad), and on the ribs corresponding to the upper thoracic vertebra (axillary extension pad)). The rectification process requires the skill and experience of an orthotist; however, this study demonstrates that the brace shape, location, and volume of material removed from the pre-rectification mold can be characterized and quantified. Results from this study can be fed into software that can accelerate the brace design process and make steps towards the automated digital rectification process.

Keywords: additive manufacturing, orthotics, scoliosis brace design, sculpting software, spinal deformity

Procedia PDF Downloads 133

Authors: Hyun-Sook Lee, Hongjae Moon, Hwaebong Jung, Sumin Kim, Wooyoung Lee

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Low-temperature phase (LTP) of MnBi has attracted much attention because it has a larger coercivity than that of Nd-Fe-B at high temperature, which gives high potential as a permanent magnet material that can be used at such high temperature. We present variation in magnetic properties of MnBi films by controlling the numbers of Bi/Mn bilayer. The thin films of LTP-MnBi were fabricated onto glass substrates by UHV sputtering, followed by in-situ annealing process at an optimized condition of 350 °C and 1.5 hours. The composition ratio of Bi/Mn was adjusted by varying the thickness of Bi and Mn layers. The highest value of (BH)max ~ 8.6 MGOe at room temperature was obtained in one Bi/Mn bilayer with 34 nm Bi and 16 nm Mn. To investigate the effect of Bi/Mn multilayers on the magnetic properties, we increased the numbers of Bi/Mn bilayer up to five at which the total film thicknesses of Bi and Mn were fixed with 34 nm and 16 nm. The increase of coercivity was observed up to three layers from 4.8 kOe to 15.3 kOe and then suppression was appeared. A reversed behavior was exhibited in the magnetization. We found that these were closely related to a microstructural change of LTP-MnBi and a reduction of growth rate of LTP-MnBi by analyzing XRD and TEM results. We will discuss how the multilayered MnBi affects the magnetic properties in details.

Keywords: coercivity, MnBi, multilayer film, permanent magnet

Procedia PDF Downloads 322