Search results for: microscopy.

Authors: A. Alhazza, B. Alnaser

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Orthodontic restorative materials are widely used for the direct restoration of teeth or for cosmetic dentistry purposes. These materials have helped to solve many dental problems, providing healthy and beautiful smiles for many patients. In this study, we aimed to investigate whether the pH value has an effect on the surface structure of a nanohybrid composite material. Five different types of highly consumed beverages were selected to examine their effect on the surface structure of the nanohybrid composite material. The beverages had different pH values in the range of 3–6, i.e., they were all acidic. The material was investigated under the hardest conditions of surface exposure to the drinks by immersing the material for a long period. The specimens were examined using scanning electron microscopy (SEM) at different magnifications to investigate the effect of these beverages on the morphology of the nanohybrid composite material discs. All specimens showed an effect including pores, cracks, protrusions, and surface roughness as a result of the beverages. The degree of effect differed from one experimental group to another, but there was no relationship between the pH (acidity) value and the degree of effect on the surface structure of the specimens.

Keywords: Acidity, beverage, SEM, dentistry.

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Authors: S. F. H. Tasfy, N. A. M. Zabidi, M. S. Shaharun

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Carbon dioxide is highly thermochemical stable molecules where it is very difficult to activate the molecule and achieve higher catalytic conversion into alcohols or other hydrocarbon compounds. In this paper, series of the bimetallic Cu/ZnO-based catalyst supported by SBA-15 were systematically prepared via impregnation technique with different Cu: Zn ratio for hydrogenation of CO₂ to methanol. The synthesized catalysts were characterized by transmission electron microscopy (TEM), temperature programmed desorption, reduction, oxidation and pulse chemisorption (TPDRO), and surface area determination was also performed. All catalysts were tested with respect to the hydrogenation of CO₂ to methanol in microactivity fixed-bed reactor at 250^oC, 2.25 MPa, and H₂/CO₂ ratio of 3. The results demonstrate that the catalytic structure, activity, and methanol selectivity was strongly affected by the ratio between Cu: Zn, Where higher catalytic activity of 14 % and methanol selectivity of 92 % was obtained over Cu/ZnO-SBA-15 catalyst with Cu:Zn ratio of 7:3 wt. %. Comparing with the single catalyst, the synergetic between Cu and Zn provides additional active sites to adsorb more H₂ and CO₂ and accelerate the CO₂ conversion, resulting in higher methanol production under mild reaction conditions.

Keywords: Hydrogenation of carbon dioxide, methanol synthesis, Cu/ZnO-based catalyst, mesoporous silica (SBA-15), and metal ratio.

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Authors: Mokhtar Awang, Wei-Vern Hor, Ehsan Mohammadpour, M Zaki Abdullah, Faiz Ahmad

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Chemical and physical functionalization of multiwalled carbon nanotubes (MWCNT) has been commonly practiced to achieve better dispersion of carbon nanotubes (CNTs) in polymer matrix. This work describes various functionalization methods (acidtreatment, non-ionic surfactant treatment with TritonX-100), fabrication of MWCNT/PP nanocomposites via melt blending and characterization of mechanical properties. Microscopy analysis (FESEM, TEM, XPS) showed effective purification of MWCNTs under acid treatment, and better dispersion under both chemical and physical functionalization techniques combined, in their respective order. Tensile tests showed increase in tensile strength for the nanocomposites that contain MWCNTs up to 2 wt%. A decrease in tensile strength was seen in samples that contain 4 wt% of MWCNTs for both raw and Triton X-100 functionalized, signifying MWCNT degradation/rebundling at composition with higher content of MWCNTs. For the acid-treated MWCNTs, however, the tensile results showed slight improvement even at 4wt%, indicating effective dispersion of MWCNTs.

Keywords: Multi walled carbon nanotube (MWCNT), functionalization, dispersion, nanocomposite

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Authors: Suresh Thokchom, Partha Ghosh, Somnath Ghosh

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This paper presents the findings of an experimental investigation to study the effect of alkali content in geopolymer mortar specimens exposed to sulphuric acid. Geopolymer mortar specimens were manufactured from Class F fly ash by activation with a mixture of sodium hydroxide and sodium silicate solution containing 5% to 8% Na2O. Durability of specimens were assessed by immersing them in 10% sulphuric acid solution and periodically monitoring surface deterioration and depth of dealkalization, changes in weight and residual compressive strength over a period of 24 weeks. Microstructural changes in the specimens were studied with Scanning electron microscopy (SEM) and EDAX. Alkali content in the activator solution significantly affects the durability of fly ash based geopolymer mortars in sulphuric acid. Specimens manufactured with higher alkali content performed better than those manufactured with lower alkali content. After 24 weeks in sulphuric acid, specimen with 8% alkali still recorded a residual strength as high as 55%.

Keywords: Alkali content, acid attack, compressive strength, geopolymer

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Authors: Kashima Arora, Monika Tomar, Vinay Gupta

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Langmuir–Blodgett (LB) films of polyaniline (PANI) grown onto ITO coated glass substrates were utilized for the fabrication of Uric acid biosensor for efficient detection of uric acid by immobilizing Uricase via EDC–NHS coupling. The modified electrodes were characterized by atomic force microscopy (AFM). The response characteristics after immobilization of uricase were studied using cyclic voltammetry and electrochemical impedance spectroscopy techniques. The uricase/PANI/ITO/glass bioelectrode studied by CV and EIS techniques revealed detection of uric acid in a wide range of 0.05 mM to 1.0 mM, covering the physiological range in blood. A low Michaelis–Menten constant (Km) of 0.21 mM indicates the higher affinity of immobilized Uricase towards its analyte (uric acid). The fabricated uric acid biosensor based on PANI LB films exhibits excellent sensitivity of 0.21 mA/mM with a response time of 4 s, good reproducibility, long shelf life (8 weeks) and high selectivity.

Keywords: Uric acid; biosensor, PANI, Langmuir Blodgett films deposition.

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Authors: Abbas Nasir, Xiong Zhang, Sohail Ahmad, Yiping Cui

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Non-polar a-plane AlGaN epilayers of high structural quality have been grown on r-sapphire substrate by using metalorganic chemical vapor deposition (MOCVD). A graded non-polar AlGaN buffer layer with variable aluminium concentration was used to improve the structural quality of the non-polar a-plane AlGaN epilayer. The characterisations were carried out by high-resolution X-ray diffraction (HR-XRD), atomic force microscopy (AFM) and Hall effect measurement. The XRD and AFM results demonstrate that the Al-composition-graded non-polar AlGaN buffer layer significantly improved the crystalline quality and the surface morphology of the top layer. A low root mean square roughness 1.52 nm is obtained from AFM, and relatively low background carrier concentration down to 3.9×  cm^-3 is obtained from Hall effect measurement.

Keywords: Non-polar AlGaN epilayer, Al composition-graded AlGaN layer, root mean square, background carrier concentration.

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Authors: J. Gomez-Caturla, L. Quiles-Carrillo, J. Ivorra-Martinez, D. Garcia-Garcia, R. Balart

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The present work reports on the development of wood plastic composites based on biopolypropylene (BioPP) and mango peel flour (MPF) by extrusion and injection molding processes. PP-g-IA and dicumyl peroxide (DCP) have been used as a compatibilizer and as a free radical initiator for reactive extrusion, respectively. Mechanical and morphological properties have been characterized in order to study the compatibility of the blends. The obtained results showed that DCP and PP-g-IA improved the stiffness of BioPP in terms of elastic modulus. Moreover, they positively increased the tensile strength and elongation at break of the blends in comparison with the sample that only had BioPP and MPF on its composition, improving the affinity between both compounds. DCP and PP-g-IA even seem to have certain synergy, which was corroborated through Field Emission Scanning Electron Microscopy (FESEM) analysis. Images showed that the MPF particles had greater adhesion to the polymer matrix when PP-g-IA and DCP were added. This effect was more intense when both elements were added, observing an almost inexistent gap between MPF particles and the BioPP matrix.

Keywords: Biopolypropylene, compatibilization, mango peel flour, wood plastic composite.

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Authors: C. S. Wong, K. H. Badri, N. Ataollahi, K. P. Law, M. S. Su’ait, N. I. Hassan

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Novel bio-based polymer electrolyte was synthesized with LiClO4 as the main source of charge carrier. Initially, polyurethane-LiClO4 polymer electrolytes were synthesized via prepolymerization method with different NCO/OH ratios and labelled them as PU1, PU2, PU3 and PU4. Fourier transform infrared (FTIR) analysis indicates the co-ordination between Li+ ion and polyurethane in PU1. Differential scanning calorimetry (DSC) analysis indicates PU1 has the highest glass transition temperature (Tg) corresponds to the most abundant urethane group which is the hard segment in PU1. Scanning electron microscopy (SEM) shows the good miscibility between lithium salt and the polymer. The study found that PU1 possessed the greatest ionic conductivity and the lowest activation energy, Ea. All the polyurethanes exhibited linear Arrhenius variations indicating ion transport via simple lithium ion hopping in polyurethane. This research proves the NCO content in polyurethane plays an important role in affecting the ionic conductivity of this polymer electrolyte.

Keywords: Ionic conductivity, Palm kernel oil-based monoester polyol, polyurethane, solid polymer electrolyte.

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Authors: A.A.Rohani, A.Salehi, M.Tabrizi, S. A. Manafi, A. Fardafshari

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In this study, ZnO nano rods and ZnO ultrafine particles were synthesized by Gel-casting method. The synthesized ZnO powder has a hexagonal zincite structure. The ZnO aggregates with rod-like morphology are typically 1.4 μm in length and 120 nm in diameter, which consist of many small nanocrystals with diameters of 10 nm. Longer wires connected by many hexahedral ZnO nanocrystals were obtained after calcinations at the temperature over 600° C.The crystalline structures and morphologies of the powder have been characterized by X-ray diffraction(XRD) and Scaning electron microscopy (SEM).The result shows that the different preparation conditions such as concentration H2O, calcinations time and calcinations temperature have a lot of influences upon the properties of nano ZnO powders, an increase in the temperature of the calcinations results in an increase of the grain size and also the increase of the calcinations time in high temperature makes the size of the grains bigger. The existences of extra watter prevent nano grains from improving like rod morphology. We have obtained the smallest grain size of ZnO powder by controlling the process conditions. Finally In a suitable condition, a novel nanostructure, namely bi-rod-like ZnO nano rods was found which is different from known ZnO nanostructures.

Keywords: morphology, nano particles, ZnO, gel-Casting method.

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Authors: Yong Pan, Li Wang, Xue Qiong Su, Dong Wen Gao

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To date, nanomaterials have received extensive attention over the years because of their wide application. Various nanomaterials such as nanoparticles, nanowire, nanoring, nanostars and other nanostructures have begun to be systematically studied. The preparation of these materials by chemical methods is not only costly, but also has a long cycle and high toxicity. At the same time, preparation of nanoparticles of multi-doped composites has been limited due to the special structure of the materials. In order to prepare multi-doped composites with the same structure as macro-materials and simplify the preparation method, the Ga_xCo_1-xZnSe_0.4 (x = 0.1, 0.3, 0.5) nanoparticles are prepared by Pulse Laser Ablation (PLA) method. The particle component and structure are systematically investigated by X-ray diffraction (XRD) and Raman spectra, which show that the success of our preparation and the same concentration between nanoparticles (NPs) and target. Morphology of the NPs characterized by Transmission Electron Microscopy (TEM) indicates the circular-shaped particles in preparation. Fluorescence properties are reflected by PL spectra, which demonstrate the best performance in concentration of Ga_0.3Co_0.3ZnSe_0.4. Therefore, all the results suggest that PLA is promising to prepare the multi-NPs since it can modulate performance of NPs.

Keywords: PLA, physics, nanoparticles, multi-doped.

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Authors: Himanshu Patel, R. T. Vashi

Abstract:

Adsorption of Toluidine blue dye from aqueous solutions onto Neem Leaf Powder (NLP) has been investigated. The surface characterization of this natural material was examined by Particle size analysis, Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy and X-Ray Diffraction (XRD). The effects of process parameters such as initial concentration, pH, temperature and contact duration on the adsorption capacities have been evaluated, in which pH has been found to be most effective parameter among all. The data were analyzed using the Langmuir and Freundlich for explaining the equilibrium characteristics of adsorption. And kinetic models like pseudo first- order, second-order model and Elovich equation were utilized to describe the kinetic data. The experimental data were well fitted with Langmuir adsorption isotherm model and pseudo second order kinetic model. The thermodynamic parameters, such as Free energy of adsorption (AG"), enthalpy change (AH') and entropy change (AS°) were also determined and evaluated.

Keywords: Adsorption, isotherm models, kinetic models, temperature, toluidine blue dye, surface chemistry.

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Authors: Indah Kurniawaty, Yoki Yulizar, Haryo Satrya Oktaviano, Adam Kusuma Rianto

Abstract:

Magnesium oxide nanoparticles (MgO NP) were successfully synthesized in this study using a one-pot green synthesis mediated by Calliandra calothyrsus leaf extract (CLE). CLE was prepared by maceration of the leaf using methanol with a ratio of 1:5 for 7 days. Secondary metabolites in CLE, such as alkaloids and flavonoids, served as a weak base provider and capping agent in the formation of MgO NP. CLE Fourier Transform Infra-Red (FTIR) spectra peak at 3255 cm-1, 1600 cm-1, 1384 cm-1, 1205 cm-1, 1041 cm-1, and 667 cm-1 showing the presence of vibrations O-H stretching, N-H bending, C-C stretching, C-N stretching and N-H wagging. During the experiment, different CLE volumes and calcined temperatures were used, resulting in a variety of structures. Energy Dispersive X-ray Spectrometer (EDS) and FTIR were used to characterize metal oxide particles. MgO diffraction patterns at 2θ of 36.9°; 42.9°; 62.2°; 74.6°; and 78.5° can be assigned to crystal planes (111), (200), (220), (311), and (222), respectively. Scanning Electron Microscopy (SEM) was used to characterize the surface morphology. The morphology ranged from sphere to flower-like resulting in crystallite sizes of 28 nm, 23 nm, 12 nm, and 9 nm.

Keywords: Calliandra calothyrsus, green-synthesis, magnesium oxide, nanoparticle.

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Authors: M. Al Nur, M. S. Kaiser

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Corrosion behaviour of hypereutectic Al-19Si automotive alloy in different pH=1, 3, 5, 7, 9, 11, and 13 environments was carried out using conventional gravimetric measurements and was complemented by resistivity, optical micrograph, scanning electron microscopy (SEM) and X-ray analyzer (EDX) investigations. Gravimetric analysis confirmed that the highest corrosion rate is shown at pH 13 followed by pH 1. Minimum corrosion occurs in the pH range of 3.0 to 11 due to establishment of passive layer on the surface. The highest corrosion rate at pH 13 is due to the presence of sodium hydroxide in the solution which dissolves the surface oxide film at a steady rate. At pH 1, it can be attributed that the presence of aggressive chloride ions serves to pick up the damage of the passive films at localized regions. With varying exposure periods by both, the environment complies with the normal corrosion rate profile that is an initial steep rise followed by a nearly constant value of corrosion rate. Resistivity increases in case of pH 1 solution for the higher pit formation and decreases at pH 13 due to formation of thin film. The SEM image of corroded samples immersed in pH 1 solution clearly shows pores on the surface and in pH 13 solution, and the corrosion layer seems more compact and homogenous and not porous.

Keywords: Al-Si alloy, corrosion, pH, resistivity, SEM.

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Authors: A. A. Salisu, M. Y. Yakasai, K. M. Aujara

Abstract:

Sisal leaves were subjected to enzymatic retting method to extract the sisal fibre. A portion of the fibre was pretreated with alkali (NaOH), and further treated with benzoyl chloride and silane treatment reagents. Both the treated and untreated Sisal fibre composites were used to fabricate the composite by hand lay-up technique using unsaturated polyester resin. Tensile, flexural, water absorption, density, thickness swelling and chemical resistant tests were conducted and evaluated on the composites. Results obtained for all the parameters showed an increase in the treated fibre compared to untreated fibre. FT-IR spectra results ascertained the inclusion of benzoyl and silane groups on the fibre surface. Scanning electron microscopy (SEM) result obtained showed variation in the morphology of the treated and untreated fibre. Chemical modification was found to improve adhesion of the fibre to the matrix, as well as physico-mechanical properties of the composites.

Keywords: Chemical resistance, density test, Sisal fibre, polymer matrix, thickness swelling.

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Authors: M. Sajjadnejad, H. Karimi Abadeh

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In this research, zinc coatings were fabricated by electroplating process in a sulfate solution under direct and pulse current conditions. In direct and pulse current conditions, effect of maximum current was investigated on the coating properties. Also a comparison was made between the obtained coatings under direct and pulse current. Morphology of the coatings was investigated by scanning electron microscopy (SEM). Corrosion behavior of the coatings was investigated by potentiodynamic polarization test. In pulse current conditions, the effect of pulse frequency and duty cycle was also studied. The effect of these conditions and parameters were also investigated on morphology and corrosion behavior. All of DC plated coatings are showing a distinct passivation area in -1 to -0.4 V range. Pulsed current coatings possessed a higher corrosion resistance. The results showed that current density is the most important factor regarding the fabrication process. Furthermore, a rise in duty cycle deteriorated corrosion resistance of coatings. Pulsed plated coatings performed almost 10 times better than DC plated coatings.

Keywords: Corrosion, duty cycle, pulsed current, zinc.

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Authors: Elnasharty M., El Sharaby A., Nor El-din A.

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The gustatory system allows animals to distinguish varieties of food and affects greatly the consumption of food, hence the health and growth of animals. In the current study, we investigated the histogenesis of vallate papillae (VLP) in the rabbit tongue using light and scanning electron microscopy. Samples were obtained from rabbit embryos at the embryonic days 16-30 (E16-30), and from newborns until maturity; 6 months. At E16, the first primordia of vallate papillae were observed as small pits on the surface epithelium of the tongue-s root. At E18, the caudal part was prominent with loose mesenchymal tissue core; meanwhile the rostral part of the papilla was remained as a thick mass of epithelial cells. At E20-24, the side epithelium formed the primitive annular groove. At E26, the primitive taste buds appeared only at the papillary surface and reached their maturity by E28. The annular groove started to appear at E26 became more defined at E28. The definitive vallate papillae with substantial number of apparently mature taste buds were observed by the end of the second week. We conclude that the vallate papillae develop early and mature during the early postnatal life.

Keywords: Rabbit, vallate papillae, histogenesis, taste buds.

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Authors: S. N. Hosseini, M. H. Enayati, F. Karimzadeh, N. M. Sammes

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The synthesis of CuFe2O4 spinel powders by an optimized combustion-like process followed by calcination is described herein. The samples were characterized using X-ray diffraction (XRD), differential thermal analysis (TG/DTA), scanning electron microscopy (SEM), dilatometry and 4-probe DC methods. Different glycine to nitrate (G/N) ratios of 1 (fuel-deficient), 1.48 (stoichiometric) and 2 (fuel-rich) were employed. Calcining the asprepared powders at 800 and 1000°C for 5 hours showed that the G/N ratio of 2 results in the formation of the desired copper spinel single phase at both calcination temperatures. For G/N=1, formation of CuFe2O4 takes place in three steps. First, iron and copper nitrates decompose to iron oxide and pure copper. Then, copper transforms to copper oxide and finally, copper and iron oxides react with each other to form a copper ferrite spinel phase. The electrical conductivity and the coefficient of thermal expansion of the sintered pelletized samples were 2 S.cm-1 (800°C) and 11×10-6 °C-1 (25-800°C), respectively.

Keywords: SOFC interconnect coatings, Copper ferrite, Spinels, Electrical conductivity, Glycine–nitrate process.

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Authors: M. I. Aida Isma, Azni Idris, Rozita Omar, A. R. Putri Razreena

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40L of hollow fiber membrane bioreactor with solids retention times (SRT) of 30, 15 and 4 days were setup for treating synthetic wastewater at hydraulic retention times (HRT) of 12, 8 and 4 hours. The objectives of the study were to investigate the effects of SRT and HRT on membrane fouling. A comparative analysis was carried out for physiochemical quality parameters (turbidity, suspended solids, COD, NH₃-N and PO₄^3-). Scanning electron microscopy (SEM), energy diffusive X-ray (EDX) analyzer and particle size distribution (PSD) were used to characterize the membrane fouling properties. The influence of SRT on the quality of effluent, activated sludge quality, and membrane fouling were also correlated. Lower membrane fouling and slower rise in trans-membrane pressure (TMP) were noticed at the longest SRT and HRT of 30d and 12h, respectively. Increasing SRT results in noticeable reduction of dissolved organic matters. The best removal efficiencies of COD, TSS, NH₃-N and PO₄^3- were 93%, 98%, 80% and 30% respectively. The high HRT with shorter SRT induced faster fouling rate. The main fouling resistance was cake layer. The most severe membrane fouling was observed at SRT and HRT of 4 and 12, respectively with thickness cake layer of 17mm as reflected by higher TMP, lower effluent removal and thick sludge cake layer.

 

Keywords: Membrane bioreactor, SRT, HRT, membrane fouling.

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Authors: C. Gallottini, W. Di Mari, C. De Carolis, A. Dolci, G. Dolci, L. Gallottini, G. Barraco, S. Eramo

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The aim of this paper is to summarize the literature on micromorphology and composition of the enamel of the cat and present an original experiment by SEM on how it responds to the etching with ortophosphoric acid for the time recommended in the veterinary literature (30", 45", 60"), derived from research and experience on human enamel; 21 teeth of cat were randomly divided into three groups of 7 (A, B, C): Group A was subjected to etching for 30 seconds by means of orthophosphoric acid to 40% on a circular area with diameter of about 2mm of ​​the enamel coronal; the Groups B and C had the same treatment but, respectively, for 45 and 60 seconds. The samples obtained were observed by SEM to constant magnification of 1000x framing, in particular, the border area between enamel exposed and not exposed to etching to highlight differences. The images were subjected to the analysis of three blinded experienced operators in electron microscopy. In the enamel of the cat the etching for the times considered is not optimally effective for the purpose adhesives and the presence of a thick prismless layer could explain this situation. To improve this condition may clinically in the likeness of what is proposed for the enamel of human deciduous teeth: a bevel or a chamfer of 1 mm on the contour of the cavity to discover the prismatic enamel and increase the bonding surface.

Keywords: SEM, Cat, Enamel

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Authors: Woei-Shyan Lee, Shuo-Ling Chang

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The nanoindentation behaviour and phase transformation of annealed single-crystal silicon wafers are examined. The silicon specimens are annealed at temperatures of 250, 350 and 450ºC, respectively, for 15 minutes and are then indented to maximum loads of 30, 50 and 70 mN. The phase changes induced in the indented specimens are observed using transmission electron microscopy (TEM) and micro-Raman scattering spectroscopy (RSS). For all annealing temperatures, an elbow feature is observed in the unloading curve following indentation to a maximum load of 30 mN. Under higher loads of 50 mN and 70 mN, respectively, the elbow feature is replaced by a pop-out event. The elbow feature reveals a complete amorphous phase transformation within the indented zone, whereas the pop-out event indicates the formation of Si XII and Si III phases. The experimental results show that the formation of these crystalline silicon phases increases with an increasing annealing temperature and indentation load. The hardness and Young’s modulus both decrease as the annealing temperature and indentation load are increased.

Keywords: Nanoindentation, silicon, phase transformation, amorphous, annealing.

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Authors: Roman Major, Klaudia Trembecka-Wojciga, Juergen Markus Lackner, Boguslaw Major

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The future and the development of science is therefore seen in interdisciplinary areas such as biomedical engineering. Selfassembled structures, similar to stem cell niches would inhibit fast division process and subsequently capture the stem cells from the blood flow. By means of surface topography and the stiffness as well as microstructure progenitor cells should be differentiated towards the formation of endothelial cells monolayer which effectively will inhibit activation of the coagulation cascade. The idea of the material surface development met the interest of the clinical institutions, which support the development of science in this area and are waiting for scientific solutions that could contribute to the development of heart assist systems. This would improve the efficiency of the treatment of patients with myocardial failure, supported with artificial heart assist systems. Innovative materials would enable the redesign, in the post project activity, construction of ventricular heart assist.

Keywords: Bio-inspired materials, electron microscopy, haemocompatibility, niche-like structures, thin coatings.

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Authors: Aneeqa Sabah, Saadat Anwar Siddiqi, Salamat Ali

Abstract:

The systematic manipulations of shapes and sizes of inorganic compounds greatly benefit the various application fields including optics, magnetic, electronics, catalysis and medicine. However shape control has been much more difficult to achieve. Hence exploration of novel method for the preparation of differently shaped nanoparticles is challenging research area. II-VI group of semiconductor cadmium sulphide (CdS) nanostructure with different morphologies (such as, acicular like, mesoporous, spherical shapes) and of crystallite sizes vary from 11 to 16 nm were successfully synthesized by chemical aqueous precipitation of Cd2+ ions with homogeneously released S2- ions from decomposition of cadmium sulphate (CdSO4) and thioacetamide (CH3CSNH2) by annealing at different radiations (microwave, ultrasonic and sunlight) with matter and systematic research has been done for various factors affecting the controlled growth rate of CdS nanoparticles. The obtained nanomaterials have been characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravometric (DSC-TGA) analysis and Scanning Electron Microscopy (SEM). The result indicates that on increasing the reaction time particle size increases but on increasing the molar ratios grain size decreases.

Keywords: CdS nanoparticles, Morphology, Oxidation, Radiations

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Authors: Kaustubh Chakradeo, Michael Delves, Sofya Titarenko

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Malaria is a serious disease which affects hundreds of millions of people around the world, each year. If not treated in time, it can be fatal. Despite recent developments in malaria diagnostics, the microscopy method to detect malaria remains the most common. Unfortunately, the accuracy of microscopic diagnostics is dependent on the skill of the microscopist and limits the throughput of malaria diagnosis. With the development of Artificial Intelligence tools and Deep Learning techniques in particular, it is possible to lower the cost, while achieving an overall higher accuracy. In this paper, we present a VGG-based model and compare it with previously developed models for identifying infected cells. Our model surpasses most previously developed models in a range of the accuracy metrics. The model has an advantage of being constructed from a relatively small number of layers. This reduces the computer resources and computational time. Moreover, we test our model on two types of datasets and argue that the currently developed deep-learning-based methods cannot efficiently distinguish between infected and contaminated cells. A more precise study of suspicious regions is required.

Keywords: Malaria, deep learning, DL, convolution neural network, CNN, thin blood smears.

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Authors: Aswin Kumar Krishnan, Yat Choy Wong, Reiza Mukhlis, Zipeng Zhang, Arul Arulrajah

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The continuous increase in vehicle uptake escalates the number of rubber tyres waste which need to be managed to avoid landfilling and stockpiling. The present research focused on the sustainable use of crumb rubber in clay roof tiles. The properties of roof tiles composed of clay, crumb rubber, NaOH, and Na2SiO3 with 10 wt.% alkaline activator were studied. Tile samples were fabricated by heating the compacted mixtures at 50 °C for 72 hours, followed by a higher heating temperature of 200 °C for 24 hours. The effect of crumb rubber aggregates as a substitution for the raw clay materials were investigated by varying their concentration from 0 wt.% to 2.5 wt.%. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses have been conducted to study the phases and microstructures of the samples. It was found that the optimum rubber crumbs concentration was at 0.5 wt.% and 1 wt.%, while cracks and larger porosity were found at higher crumbs concentration. Water absorption, and compressive strength test results demonstrated that rubber crumbs and clay satisfied the standard requirement for the roof tiles.

Keywords: Crumb rubber, clay, roof tiles, alkaline activators.

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Authors: Zhanat Shomanova, Ruslan Safarov, Yuri Nosenko, Zheneta Tashmuchambetova, Alima Zharmagambetova

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An effective way of utilization of ferroalloy production wastes is preparing hydrocarbon refining catalysts from them. It is possible due to accordable transition metals containing in the wastes. In the work, we are presenting the results on elemental analysis of sludge samples from Aksu ferroalloy plant (Aksu, Kazakhstan), method of catalysts preparing, results of physical-chemical analysis of obtained catalysts (X-ray analysis, electron microscopy, the BET method etc.), results of using the catalysts in some hydrocarbons refining processes such as hydrocracking of rubber waste, cracking of gasoil, oxidation of cyclohexane. The main results of catalytic activity research are: a) In hydrocracking of rubber waste 64.9% of liquid products were fuel fractions; b) In cracking of gasoil conversion was 51% and selectivity by liquid products was 99%; c) In oxidation of cyclohexane the maximal product yield 87.9% and selectivity by cyclohexanol 93.0% were achieved.

Keywords: Catalyst, cyclohexane oxidation, ferroalloy production waste, gasoil cracking.

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Authors: I. Yalcin Enis, J. Vojtech, T. Gok Sadikoglu

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In this study, polycaprolactone (PCL) was dissolved in chloroform:ethanol solvent system at a concentration of 18 w/v %. 1, 2, 4, and 6 droplets of formic acid were added to the prepared 10ml PCL-chloroform:ethanol solutions separately. Fibrous webs were produced by electrospinning technique based on the horizontal working principle. Morphology of the webs was investigated by using scanning electron microscopy (SEM) whereas fiber diameters were measured by Image J Software System. The effect of formic acid addition to the mostly used chloroform solvent on fiber morphology was examined. Results indicate that there is a distinct fall in fiber diameter with the addition of formic acid drops. The average fiber diameter was measured as 2.22μm in PCL /chloroform:ethanol solution system. On the other hand, 328nm and 256 nm average fiber diameters were measured for the samples of 4 drops and 6 drops formic acid added. This study offers alternative solvent systems to produce nanoscaled, nontoxic PCL fibrous webs by electrospinning technique.

Keywords: Chloroform, electrospinning, formic acid polycaprolactone.

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Authors: A. Karnis, L. Gautron

Abstract:

Considering toxicity of heavy metals and their accumulation in domestic wastes, immobilization of lead and cadmium is envisaged inside glass-ceramics. We particularly focused this work on calcium-rich phases embedded in a glassy matrix. Glass-ceramics were synthesized from glasses doped with 12 wt% and 16 wt% of PbO or CdO. They were observed and analyzed by Electron MicroProbe Analysis (EMPA) and Analytical Scanning Electron Microscopy (ASEM). Structural characterization of the samples was performed by powder XRay Diffraction. Diopside crystals of CaMgSi2O6 composition are shown to incorporate significant amounts of cadmium (up to 9 wt% of CdO). Two new crystalline phases are observed with very high Cd or Pb contents: about 40 wt% CdO for the cadmiumrich phase and near 60 wt% PbO for the lead-rich phase. We present complete chemical and structural characterization of these phases. They represent a promising way for the immobilization of toxic elements like Cd or Pb since glass ceramics are known to propose a “double barrier" protection (metal-rich crystals embedded in a glass matrix) against metal release in the environment.

Keywords: Cadmium, Calcium-rich phases, Diopside, Domesticwastes, Fly ashes, Glass-ceramics, Lead, Municipal Solid WasteIncineration.

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Authors: Erdinç Vural, Bülent Özdalyan, Serkan Özel

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The four-stroke single cylinder diesel engine has been used in this study, the pistons and valves of the engine have been stabilized, the aluminum oxide (Al₂O₃) in different ratios has been added in the power of zirconium (ZrO₂) magnesium oxide (MgO), and has been coated with the plasma spray method. The pistons and valves of the combustion chamber of the engine are coated with 5 different (ZrO₂ + MgO), (ZrO₂ + MgO + 25% Al₂O₃), (ZrO₂ + MgO + 50% Al₂O₃), (ZrO₂ + MgO + 75% Al₂O₃), (Al₂O₃) sample. The material tests have been made for each of the coated engine parts with the scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) using Cu Kα radiation surface analysis methods. The engine tests have been repeated for each sample in any electric dynamometer in full power 1600 rpm, 2000 rpm, 2400 rpm and 2800 rpm engine speeds. The material analysis and engine tests have shown that the best performance has been performed with (ZrO₂ + MgO + 50% Al₂O₃). Thus, there is no significant change in HC and Smoke emissions, but NOx emission is increased, as the engine improves power, torque, specific fuel consumption and CO emissions in the tests made with sample A3.

Keywords: Ceramic coating, material characterization, engine performance, exhaust emissions.

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Authors: Zainudin Kornain, Azman Jalar, Rozaidi Rasid, Fong Chee Seng

Abstract:

Void formation in underfill is considered as failure in flip chip manufacturing process. Void formation possibly caused by several factors such as poor soldering and flux residue during die attach process, void entrapment due moisture contamination, dispense pattern process and setting up the curing process. This paper presents the comparison of single step and two steps curing profile towards the void and black dots formation in underfill for Hi-CTE Flip Chip Ceramic Ball Grid Array Package (FC-CBGA). Statistic analysis was conducted to analyze how different factors such as wafer lot, sawing technique, underfill fillet height and curing profile recipe were affected the formation of voids and black dots. A C-Mode Scanning Aqoustic Microscopy (C-SAM) was used to scan the total count of voids and black dots. It was shown that the 2 steps curing profile provided solution for void elimination and black dots in underfill after curing process.

Keywords: black dots formation, curing profile, FC-CBGA, underfill, void formation,

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Authors: Bruno Bacci Fernandes, Stephan Mändl, Ataíde Ribeiro da Silva Junior, José Osvaldo Rossi, Mário Ueda

Abstract:

Nitrogen implantation in aluminum and its alloys is acquainted for the difficulties in obtaining modified layers deeper than 200 nm. The present work addresses a new method to overcome such a problem; although, the coating with nitrogen and oxygen obtained by plasma immersion ion implantation (PIII) into a 7075 aluminum alloy surface was too shallow. This alloy is commonly used for structural parts in aerospace applications. Such a layer was characterized by secondary ion mass spectroscopy, electron microscopy, and nanoindentation experiments reciprocating wear tests. From the results, one can assume that the wear of this aluminum alloy starts presenting severe abrasive wear followed by an additional adhesive mechanism. PIII produced a slight difference, as shown in all characterizations carried out in this work. The results shown here can be used as the scientific basis for further nitrogen PIII experiments in aluminum alloys which have the goal to produce thicker modified layers or to improve their surface properties.

Keywords: Aluminum alloys, plasma immersion ion implantation, tribological properties, hardness, nanofatigue.

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