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Green synthesis and Characterization of Gold Nanoparticles Using Leaf Extracts of Withania somnifera (Linn.) (Ashwagandha)
Birendra Kumar Bindhani,
Ashok Kumar Panigrahi
Issue:
Volume 3, Issue 6, November 2014
Pages:
279-284
Received:
28 August 2014
Accepted:
10 September 2014
Published:
30 September 2014
Abstract: In this study, a novel technique for biosynthesizing of gold nanoparticles (GNPs) using Withania somnifera as reductants and stabilizers is reported. Biosynthesis of anisotropic gold nanoparticles using ethanolic extract of Withania somnifera leaf and their potential as IR blockers has been demonstrated. The phenolic groups (–OH) residue was identified as the active functional group for gold ion reduction. These gold nanoparticles were characterized by of UV–Vis spectrophotometer, FTIR, TEM. The presence of proteins was identified by FTIR, UV–Vis and fluorescence spectroscopy. The micrograph revealed the formation of anisotropic gold nanoaprticles. The characteristics of the nanoparticles formed suggest application of gold and gold nanoparticles as chemical sensors in the future. Given the simple and eco-friendly approach for synthesis, these nanoparticles could easily be commercialized for large scale production. The present research opens a new avenue for the green synthesis of nanomaterials.
Abstract: In this study, a novel technique for biosynthesizing of gold nanoparticles (GNPs) using Withania somnifera as reductants and stabilizers is reported. Biosynthesis of anisotropic gold nanoparticles using ethanolic extract of Withania somnifera leaf and their potential as IR blockers has been demonstrated. The phenolic groups (–OH) residue was identi...
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Intercalation of Metallic Potassium and Fullerene C60 into Natural Graphite
Zemanova Eva,
Klouda Karel,
Lach Karel,
Weisheitelova Marketa
Issue:
Volume 3, Issue 6, November 2014
Pages:
285-292
Received:
1 September 2014
Accepted:
23 September 2014
Published:
10 October 2014
Abstract: Graphite was intercalated with potassium to produce C8K intercalate which was subsequently exposed to suspension of fullerene C60 in toluene. The resulting product stabilized potassium against effects of the atmosphere. The prepared product was exposed to tests of thermal stability and other analyses, such as FT-IR, SEM and Energy-dispersive X-ray Spectroscopy (EDAX) with the objective to describe arrangement of potassium in the carbon matrix. The product with stabilized potassium in a carbon skeleton (graphite – fullerite) is partly able to resist the atmosphere, it is relatively thermally stable (up to 150 oC) and the energy effects of its decomposition are low up to 600 oC. The product may be used in numerous applications – catalysis, hydrogen storage and as an admixture component in aerosol fire suppression systems.
Abstract: Graphite was intercalated with potassium to produce C8K intercalate which was subsequently exposed to suspension of fullerene C60 in toluene. The resulting product stabilized potassium against effects of the atmosphere. The prepared product was exposed to tests of thermal stability and other analyses, such as FT-IR, SEM and Energy-dispersive X-ray ...
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Fullerene C60, Graphene-Oxide and Graphene-Oxide Foil with Fullerene and their Bromination
Klouda Karel,
Zemanova Eva,
Friedrichova Romana,
Weisheitova Marketa
Issue:
Volume 3, Issue 6, November 2014
Pages:
293-302
Received:
5 September 2014
Accepted:
23 September 2014
Published:
10 October 2014
Abstract: A direct reaction with liquid bromine was used to prepare bromofullerene C60Br14-18. The brominated derivative reacted with previously prepared graphene-oxide (hereinafter GO), according to a method described by Hummer. The same method was used to oxidize graphite alone. The prepared graphite fullerene foil was brominated with liquid bromine and the graphene-oxide foil was reacted with bromofullerene. FT-IR analysis of all the obtained products was performed and also TGA analysis to investigate particularly their thermal stability. The brominated products demonstrate lower thermal effects when thermally decomposed which is caused by the retarding ability of bromine.
Abstract: A direct reaction with liquid bromine was used to prepare bromofullerene C60Br14-18. The brominated derivative reacted with previously prepared graphene-oxide (hereinafter GO), according to a method described by Hummer. The same method was used to oxidize graphite alone. The prepared graphite fullerene foil was brominated with liquid bromine and th...
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An In-Situ Anion Exchange Method Synthesized of Ag3PO4 Functionalized with Fe3O4 and AgI for Photocatalytic Degradation of Methyl Orange under Visible Light Irradiation
Ahmed Mahmoud Idris,
Mahgoub Ibrahim Shinger,
Dong Dong Qin,
Hind Baballa,
Xiaoquan Lu
Issue:
Volume 3, Issue 6, November 2014
Pages:
303-308
Received:
18 August 2014
Accepted:
1 September 2014
Published:
20 October 2014
Abstract: A novel of visible light induced photodegradation of methyl orange over Fe3O4-Ag3PO4@AgI photocatalyst has been observed. The nanoparticles have been synthesized by a facile and effective in-situ ion exchange method and characterized by scanning electron microscopy (SEM), X-ray diffraction meter (XRD) and UV−visible diffuse reflectance spectroscopy. The results show that the magnetic nanoparticles and AgI molecules are immobilized on surface of Ag3PO4 without the loss of photo functionality and magnetic properties. The Fe3O4-Ag3PO4@AgI has exhibited higher photocatalytic activity better than Ag3PO4@AgI and Ag3PO4 respectively. The photocatalytic activity of Fe3O4-Ag3PO4@AgI was evaluated by degradation of the methyl orange nearly 100% after short irradiation time with a good recyclability.
Abstract: A novel of visible light induced photodegradation of methyl orange over Fe3O4-Ag3PO4@AgI photocatalyst has been observed. The nanoparticles have been synthesized by a facile and effective in-situ ion exchange method and characterized by scanning electron microscopy (SEM), X-ray diffraction meter (XRD) and UV−visible diffuse reflectance spectroscopy...
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Simulation of the Carbides Precipitation Mechanism in 34CrMo4 and 42CrMo4 Steels
Miroslav Kvicala,
Michaela Stamborska
Issue:
Volume 3, Issue 6, November 2014
Pages:
309-313
Received:
25 September 2014
Accepted:
8 October 2014
Published:
20 October 2014
Abstract: The low-alloyed Cr-Mo steels (25CrMo4, 34CrMo4 and 42CrMo4) are used for production of important technical equipment parts in the petrochemical industry, for transportation of the gaseous hydrocarbons, concentrated acids, and lyes. They are also used for rolling of seamless tubes, in the production of pressure bottles, steel bolts, etc. Steel grades 25CrMo4 and 34CrMo4 represents materials with improved mechanical properties, mainly due to vanadium microalloying. Unfortunately, vanadium microalloyed steels are very sensitive to cracks occurrence after continuous casting and/or heating before hot rolling. This paper deals with vanadium rich precipitates MC, M3C2 and M7C3 formation during continuous casting process. It was verified that vanadium microalloyed steel 34CrMo4 exhibited different carbides formation mechanism and contained significantly higher rate of vanadium in MxCy carbides than steel grade 42CrMo4 using experimental data and ThermoCalc software. Understanding of the vanadium precipitation kinetics is necessary for manufacturing process optimization and internal defects limitation.
Abstract: The low-alloyed Cr-Mo steels (25CrMo4, 34CrMo4 and 42CrMo4) are used for production of important technical equipment parts in the petrochemical industry, for transportation of the gaseous hydrocarbons, concentrated acids, and lyes. They are also used for rolling of seamless tubes, in the production of pressure bottles, steel bolts, etc. Steel grade...
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Thickness Dependency of CuO Nanocoating Layer on Thermal Performance of HPHE
Aysar Abd Alrazaq Alamery,
Hussein Ali Jawad,
Zainab Fadhil Mahdi
Issue:
Volume 3, Issue 6, November 2014
Pages:
314-320
Received:
8 July 2014
Accepted:
24 July 2014
Published:
20 October 2014
Abstract: Among the different passive techniques present, surface coating seems to the most effective one. Copper oxide-based materials are of interest on account of their potential uses in many technological fields. Modeling of the nanocoating on fins in Thermosyphon heat exchangers using ANSYS software is introduced. The temperature distribution was investigated. Seven thicknesses of CuO coating layers are used on fins of HPHE with the aim of improving working system. The enhancement is proportioning with the increment in coat thickness at the evaporator section of transient conditions (-16.95, 3.12, 30.66, 52.68, 70.65, 85.55and 98.09) for (10, 25, 50, 75, 100,125and150 µm) thicknesses respectively. From these results, maximum enhancement occurred at150 µm coat. Coat process of the evaporator fins can give fast response of nanofluid to absorb the latent heat from the outdoor air and vaporize to start the closed cycle working system so the increasing in the energy saving is investigated.
Abstract: Among the different passive techniques present, surface coating seems to the most effective one. Copper oxide-based materials are of interest on account of their potential uses in many technological fields. Modeling of the nanocoating on fins in Thermosyphon heat exchangers using ANSYS software is introduced. The temperature distribution was invest...
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Determination of Friction Coefficient between Glass Fiber and the Concrete Fri (GF.C)
Issue:
Volume 3, Issue 6, November 2014
Pages:
321-324
Received:
28 September 2014
Accepted:
10 October 2014
Published:
20 October 2014
Abstract: The friction forces between glass fiber and the concrete in the case of Fiber Reinforced Concrete F.R.C are considered as the main factor to generate the bonding between these two building construction materials. In the case of using glass fiber as reinforcement material to improve the resistance capacity of plain concrete under an axial or flexural tension forces, bonding forces at the interface between the glass fiber and the concrete matrix must be satisfactory. Bonding forces between these two materials are generated due to friction forces at the interface; therefore the final evaluation of the bonding forces is related with the real value of the friction forces, consequently the friction coefficient value between glass fiber and the concrete is important to evaluate and calculate the real value of friction forces. This paper is devoted to introduce an experimental studies about the mechanism of glass fiber removing from concrete matrix which are named (pull-out tests) as well as a programming simulations prepared to represent this mechanism too, theses laboratory experiments and computer simulations have been used in determination process of the friction coefficient value between the glass fiber and the concrete matrix Fri(GF.C).
Abstract: The friction forces between glass fiber and the concrete in the case of Fiber Reinforced Concrete F.R.C are considered as the main factor to generate the bonding between these two building construction materials. In the case of using glass fiber as reinforcement material to improve the resistance capacity of plain concrete under an axial or flexura...
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Thermal-Gravimetric, Calorimetric and Chemical Analytical Characterisation of Coal
Misael Silas Nadiye-Tabbiruka,
Wilfred Ddamba,
Kifilwe Tsheko,
Zakarea Kenewang,
Estella Judith Salamula
Issue:
Volume 3, Issue 6, November 2014
Pages:
325-330
Received:
25 September 2014
Accepted:
11 October 2014
Published:
20 October 2014
Abstract: Coal samples from Morupule colliery in Botswana were characterized by bomb calorimetry, thermal-gravimetric analysis, atomic absorption spectrometry and flame photometry. The average heat of combustion of the coal was found to be 27.3 kJ g-1; with a substantial amount of ashes left behind. Thermo-gravimetric analysis showed peaks at 59.40 oC corresponding to loss of surface water, an exothermic peak at 448.54 0C associated with primary devolatilization in which compounds containing carbon, hydrogen and oxygen are released and finally a second exothermic peak at 682.58 0C associated with the secondary degasification in which methane and hydrogen are released. 70.4% of the coal was left after heating to 1000 0C indicating that in its present form, Morupule coal is of low quality but releases plenty of heat on combustion. The determination of the percentage weights of Calcium, Chromium, Copper, Lead, Iron using Atomic Absorption Spectrometry (AAS) and that of Potassium and Sodium using flame photometry showed that Iron (21.0956%) is the dominant inorganic element. The percentage weights of the other elements varied between zero and 7.4301%.
Abstract: Coal samples from Morupule colliery in Botswana were characterized by bomb calorimetry, thermal-gravimetric analysis, atomic absorption spectrometry and flame photometry. The average heat of combustion of the coal was found to be 27.3 kJ g-1; with a substantial amount of ashes left behind. Thermo-gravimetric analysis showed peaks at 59.40 oC corres...
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Can Anodic Aluminium Oxide Nanomembranes Treated with Nanometre Scale Hydroxyapatite be Used as a Cell Culture Substrate
Gerrard Eddy Jai Poinern,
Xuan Le,
Mark O’Dea,
Derek Fawcett
Issue:
Volume 3, Issue 6, November 2014
Pages:
331-338
Received:
28 August 2014
Accepted:
11 September 2014
Published:
30 October 2014
Abstract: In this study we investigate the biomedical potential of composite membranes composed of anodic aluminium oxide (AAO) and nanometre scale hydroxyapatite (HAP). The nano-porous AAO membranes were produced using a temperature controlled two-step anodization technique. The AAO/HAP composite membranes were formed using the solution template wetting technique. The Cercopithecus aethiops (African green monkey) Kidney (Vero) epithelial cell line was used to demonstrate the biocompatibility of the synthesised membranes and composites. Investigating cell adhesion, morphology and proliferation over a 72 h period assessed cellular interactions and responses of the cell line to the various membranes types.
Abstract: In this study we investigate the biomedical potential of composite membranes composed of anodic aluminium oxide (AAO) and nanometre scale hydroxyapatite (HAP). The nano-porous AAO membranes were produced using a temperature controlled two-step anodization technique. The AAO/HAP composite membranes were formed using the solution template wetting tec...
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Gamma Irradiation Inducing the Synthesis of Magnetic Fe3O4 Nanorod Particles in Alkaline Medium
Gracien Bakambo Ekoko,
Joseph Kanza-Kanza Lobo,
Omer Muamba Mvele,
Jérémie Lunguya Muswema,
Jean-Felix Senga Yamambe,
Peter Kimpende Mangwala
Issue:
Volume 3, Issue 6, November 2014
Pages:
339-343
Received:
8 October 2014
Accepted:
25 October 2014
Published:
10 November 2014
Abstract: Gamma irradiation has been employed to produce magnetic nanorod particles of magnetite (Fe3O4) in alkaline medium at pH 13.2, in the presence of polyvinyl alcohol solution used as an organic surfactant molecule in order to stabilize the growth of particles during synthesis. Pure sub micron sized particles with bullet-shaped morphology were prepared at pH 11.3 and well dispersed nanorod particles of Fe3O4 were synthesized at pH 13.2. It has been proven that the morphology of the as prepared oxides is strongly dependent on the pH value of the starting solution before irradiation. It has also been shown that the gamma irradiation can efficiently induce changes in structure and in morphology of the sols prepared before gamma irradiation. The XRD analysis revealed that the sol product prepared before irradiation corresponded to the standard ferric oxyhydroxide, FeO(OH) which was transformed under gamma irradiation to ferriferrous oxide (Fe3O4). The transmission electron microscopy observations indicated that the as-synthesized nanoparticles were single crystals.
Abstract: Gamma irradiation has been employed to produce magnetic nanorod particles of magnetite (Fe3O4) in alkaline medium at pH 13.2, in the presence of polyvinyl alcohol solution used as an organic surfactant molecule in order to stabilize the growth of particles during synthesis. Pure sub micron sized particles with bullet-shaped morphology were prepared...
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Evaluation of the Rheological Behavior of a Semi-Solid Al–SiC Composite using a Parallel-Plate Drop-Forge Viscometer
Yasuyoshi Fukui,
Daisaku Nara,
Kazuyo Fushimi,
Noriyoshi Kumazawa
Issue:
Volume 3, Issue 6, November 2014
Pages:
344-352
Received:
22 October 2014
Accepted:
6 November 2014
Published:
20 November 2014
Abstract: This paper presents of studies performed to assess the effect of rheological behavior on the near-net shape forming of an Al–20 vol% SiC composite of Duralcan F3A.20S and of the mother aluminum alloy A356 for comparison. Isothermal experiments were conducted using results of a parallel-plate drop-forge viscometer in a temperature range from 849 K (576 ºC) to 862 K (590 ºC). Each experiment indicated that the viscosity decreased in the early increasing shear rate stage and subsequently increased with decreasing shear rate. The overall relationship between the viscosity,μ[Pa.s], and the shear rate,γ[s-1], can be described by a power-law model of μ= 3.2 × 107γ-1.5 for Duralcan and μ = 1.6 × 107γ-1.5 for A356. The power-law index was the same for both materials, whereas the power-law constant of Duralcan was two times greater than that of the A356 mother alloy because of the distribution of 20 vol% SiC particles. The decrease in the viscosity that accompanied an increase in the shear rate depended on both the temperature and the applied force. The viscosities of 32 kPa.s for both Duralcan and A356 at the maximum effective duration of deformation, which obtained from the plot as a function of the viscosity, appeared to be the points at which the dominant factor governing the visco-plastic flow process transitions from plastic forming to casting. The viscosity must also represent optimum semi-solid forming conditions, as indicated by the achievement of both a moderate working time and an adequate deformation. The optimum operating temperature for both materials can be ranged from 855 K (582 ˚C) to 857 K (584 ˚C), which is just above the melting point.
Abstract: This paper presents of studies performed to assess the effect of rheological behavior on the near-net shape forming of an Al–20 vol% SiC composite of Duralcan F3A.20S and of the mother aluminum alloy A356 for comparison. Isothermal experiments were conducted using results of a parallel-plate drop-forge viscometer in a temperature range from 849 K (...
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Plasticity at Absolute Zero as a Fundamental Characteristic of Dislocation Properties
Yuly Milman,
Svitlana Chugunova,
Irina Goncharova
Issue:
Volume 3, Issue 6, November 2014
Pages:
353-362
Received:
29 October 2014
Accepted:
11 November 2014
Published:
20 November 2014
Abstract: Values of a plasticity characteristic H for different materials were determined by the indentation method at cryogenic temperatures. Using the linear dependence H(T) at low temperatures, the value of δH at 0 K, designated by δH(0), was obtained by the extrapolation method. Values of δH(0) for different materials, namely FCC, HCP and BCC metals, intermetallics, metallic glasses, quasicrystals, ceramics and covalent crystals, are discussed. An analytic expression for a dependence of δH(0) on the parameters of thermoactivated movement of dislocations, melting point and Young’s modulus E is obtained. It is shown that any type of hardening of a crystal and an increase in the Peierls–Nabarro stress σS(0) reduce δH(0). Only a rise in E leads to the simultaneous increase in σS(0) and δH(0). δH(0) can be considered as a dislocation plasticity in the absence of thermal vibrations of atoms and should be considered together with strength parameters as an important fundamental characteristic of dislocation properties.
Abstract: Values of a plasticity characteristic H for different materials were determined by the indentation method at cryogenic temperatures. Using the linear dependence H(T) at low temperatures, the value of δH at 0 K, designated by δH(0), was obtained by the extrapolation method. Values of δH(0) for different materials, namely FCC, HCP and BCC metals, ...
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Proposed Cross-Linking Model for Carboxymethyl Cellulose /Starch Superabsorbent Polymer Blend
Auda Jabbar Braihi,
Sihama Issa Salih,
Fadhel Abbas Hashem,
Jaleel Kareem Ahmed
Issue:
Volume 3, Issue 6, November 2014
Pages:
363-369
Received:
5 November 2014
Accepted:
12 November 2014
Published:
17 November 2014
Abstract: Superabsorbent polymer (SAP) blend has been synthesized from Carboxymethyl Cellulose (CMC) , starch, and aluminum sulfate octadecahydrate cross-linker. Water Absorption Capacity (WAC), FTIR, SEM, DSC, CHO, Flame Photometer and ignition tests are carried out to determine the used CMC formula, investigate the cross-linking process, and suggest a cross-linking model. Flame Photometer results showed there are two sodium acetate groups in the CMC molecule. This result confirmed by theoretical calculations and CHO test . To investigate which of Al3+ and SO42- ions causes the cross-linking : the extraction of the cross-linked CMC/starch tested with BaCl2solution(showed dense white precipitate ; sulfate group not share for blend formation), NaOH solution( showed white precipitate of aluminum hydroxide; Al3+ ion present (i.e. Al3+ ion share in the blend structure). These results confirmed by flame test for sodium ion, which showed high Na emission energy (5.75); there is an exchange between Al and Na ions. To check that aluminum is a part of the structure, sample of the cross-linked CMC ignited. A white precipitate appear for aluminum oxide ,which confirms the presence of Al. Based on that there are three CMC molecules connected to each Al atom, theoretical calculations about the amount of Al in the cross-linked CMC molecule showed a good agreement with the CHO results (5.613% Vs. 5.739 % respectively). FTIR spectrum of the cross-linked CMC/starch blend showed that there is a reaction between CMC and starch molecules; i.e. the new repeating unit contains three starch molecules. This conclusion confirmed by theoretical calculations and results of EDX, CHO, and ignition tests. Al% in the new mer appeared a good agreement between theoretical calculations (4.32%) and CHO results (4.512%). Ignition test calculations confirmed that the new mer contains three Al atoms. Evidences of the occurrence of the cross-linking process were obtained from FTIR, morphology, DSC and absorbency results. Absence of the primary hydroxyl alcohol band in the CMC/starch blend spectrum, indicates that this site is active and the reaction between starch and CMC molecules occurs through it. Morphologies studies showed that the sample after crosslinking is more compact than before as well as show one piece for after cross-linking comparing with different pieces before cross-linking.Optimum cross-linking ratio appeared to be 2wt% corresponded to WAC equal to 58 g/g.in distilled water and DSC results indicates that CMC/starch is a miscible blend.
Abstract: Superabsorbent polymer (SAP) blend has been synthesized from Carboxymethyl Cellulose (CMC) , starch, and aluminum sulfate octadecahydrate cross-linker. Water Absorption Capacity (WAC), FTIR, SEM, DSC, CHO, Flame Photometer and ignition tests are carried out to determine the used CMC formula, investigate the cross-linking process, and suggest a cro...
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A Review on Influence of Thermal Studies of Nanomaterials
Suresh Sagadevan,
B. Janarthanan
Issue:
Volume 3, Issue 6, November 2014
Pages:
370-377
Received:
24 July 2014
Accepted:
20 August 2014
Published:
1 September 2014
Abstract: Nanomaterials are defined as engineered materials with at least one dimension in the range of 1-100 nm. Particles of “nano” size have been shown to exhibit enhanced and novel properties including reactivity, greater sensing capability, and increased mechanical strength. The nanotechnique offers simple, clean, fast, efficient, and economic method for the synthesis of a variety of organic molecules, which has to provide the momentum for many chemists to switch from traditional method. To optimize the utilization of thermal conversion systems, it is essential to integrate them with thermal energy storage. In addition, study of the thermal properties of nanostructure materials against important grain growth is both scientific and technological interest. A sharp increase in grain size during consolidation of nanocrystalline powders to obtain full dense material may consequently result in the loss of some unique properties of nanocrystalline materials. The present review paper is aimed at understanding the thermal properties and its applications of nanostructure materials.
Abstract: Nanomaterials are defined as engineered materials with at least one dimension in the range of 1-100 nm. Particles of “nano” size have been shown to exhibit enhanced and novel properties including reactivity, greater sensing capability, and increased mechanical strength. The nanotechnique offers simple, clean, fast, efficient, and economic method fo...
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Numerical Simulation of Grain Size Distribution in Two-Phase Polycrystalline Materials
Rifa J. El-Khozondar,
Dana Zӧllner,
Klaus Kassner
Issue:
Volume 3, Issue 6, November 2014
Pages:
381-390
Received:
16 November 2014
Accepted:
28 November 2014
Published:
2 December 2014
Abstract: Numerical simulations based on the Monte Carlo Potts model are used to study the temporal change of the grain size distribution of two-phase polycrystalline materials, where both phases grow simultaneously. After a sufficiently long time, grain growth in such two-phase systems can be characterized by a self-similar scaled grain size distribution function and an associated growth law. In particular, the grain size distribution is analyzed for a broad range of second phase volume fractions and found to vary with the volume fraction such that the size distribution becomes narrower and higher peaked with decreasing volume fraction of the second phase, where particularly the normal distribution function describes the simulation results very well. On the other hand, for one-phase systems the grain size distribution is in excellent agreement with an analytical grain size distribution function based on a statistical mean-field theory of grain growth that is completely compatible with the principal physical condition of total volume conservation.
Abstract: Numerical simulations based on the Monte Carlo Potts model are used to study the temporal change of the grain size distribution of two-phase polycrystalline materials, where both phases grow simultaneously. After a sufficiently long time, grain growth in such two-phase systems can be characterized by a self-similar scaled grain size distribution fu...
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Machining Variables Influence on the Fatigue Life of End-Milled Aluminium Alloy
Sunday J. Ojolo,
Ifeoluwa J. Orisaleye,
Nnaemeka Obiajulu
Issue:
Volume 3, Issue 6, November 2014
Pages:
391-398
Received:
25 November 2014
Accepted:
4 December 2014
Published:
8 December 2014
Abstract: Machining involves the thermal, elastic and plastic deformations of the surface layer which result in strain hardening, structural changes and development of residual stresses. These cause surface irregularities which may increase the risk of fatigue failure of material during usage. This study involves the investigation of the influence of cutting speed, feed rate and tool geometry on the fatigue life of end-milled specimens of 2024-aluminium alloy using a design of experiment approach. The experimental design constructed was such that the specimens were subjected to different machining conditions. Data analysis was carried out with Relia Soft OfficeTM 7 DOE++ software and Analysis of Variance (ANOVA). The study showed that by decreasing the feed rate (from 60mm/min to 7mm/min) and increasing the cutting speed (from 3.77m/min to 48.25m/min) significantly resulted in a higher fatigue life (from 1.93x103 cycles to 2.53x103 cycles). Whereas, the rake angle had the least significant effect on the fatigue life, it was discovered that the feed rate was found to be the most influential factor.
Abstract: Machining involves the thermal, elastic and plastic deformations of the surface layer which result in strain hardening, structural changes and development of residual stresses. These cause surface irregularities which may increase the risk of fatigue failure of material during usage. This study involves the investigation of the influence of cutting...
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Solid Electrolyte Function of a Polyethylene Porous Membrane Filled with Side-Chain Crystalline Block Co-Polymer by Using Its Crystalline Supramolecular Interaction
Yusuke Sano,
Ryoko Nakano,
Hiroshi Sekiguchi,
Shigeru Yao
Issue:
Volume 3, Issue 6, November 2014
Pages:
399-403
Received:
25 November 2014
Accepted:
4 December 2014
Published:
16 December 2014
Abstract: Side-Chain Crystalline Block Co-Polymer (SCCBC), which is composed of a side-chain crystalline monomer unit and a functional monomer unit (which can confer solvent-compatibility, polarity, etc.), can be adsorbed to a polyethylene crystal through crystalline supramolecular interaction. By using this interaction, we can modify not only the surface but also the inner pores of a porous polyethylene membrane to give various properties. In this study, we used a monomer with ethylene oxide repeating units as a functional unit, and evaluated its potential as a solid electrolyte for use in a Li ion secondary battery. The properties of the solid electrolyte were excellent compared to those of a non-modified porous membrane at low temperature. In addition, the solid electrolyte did not show temperature-dependence, and the Li+ ion conductivity remained nearly constant throughout the temperature range of 30°C to 60 ºC. However, at high temperature (above 70 ºC), the conductivity began to decrease. This characteristic may make it useful for sensing temperature and for self-controlling thermal runaway.
Abstract: Side-Chain Crystalline Block Co-Polymer (SCCBC), which is composed of a side-chain crystalline monomer unit and a functional monomer unit (which can confer solvent-compatibility, polarity, etc.), can be adsorbed to a polyethylene crystal through crystalline supramolecular interaction. By using this interaction, we can modify not only the surface bu...
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Variation of Structural and Surface Properties of RF Sputtered Aluminum Oxide (Al2O3) Thin Films Due to the Influence of Annealing Temperature and Time
Lim Wei Qiang,
Mutharasu Devarajan
Issue:
Volume 3, Issue 6, November 2014
Pages:
404-409
Received:
5 November 2014
Accepted:
21 November 2014
Published:
18 December 2014
Abstract: Aluminum oxide (Al2O3) thin films were deposited on Si (111) substrates by using RF magnetron sputtering of Al2O3 target in Ar atmosphere. The synthesized films were annealed in the temperature range of 200 to 600°C in nitrogen (N2) environment for 2 and 4 hours. Variations in these structural and surface properties of the films were investigated using X-ray diffraction (XRD) and atomic force microscope (AFM). XRD analysis reveals that the synthesized films are in polycrystalline form with preferential orientation along (111) plane. By increasing the annealing temperature, the crystallite size of films was found to increase, whereas the micro-strain and dislocation density were decreased. The decrease in micro-strain and dislocation density was ascribed to the reduction in the lattice strain. The surface roughness of the films was increased with the increase of the annealing temperature, which was attributed to the films’ grains growth and also with the increase in RF sputtering power.
Abstract: Aluminum oxide (Al2O3) thin films were deposited on Si (111) substrates by using RF magnetron sputtering of Al2O3 target in Ar atmosphere. The synthesized films were annealed in the temperature range of 200 to 600°C in nitrogen (N2) environment for 2 and 4 hours. Variations in these structural and surface properties of the films were investigated u...
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Influence of Calcined Clay Pozzolana on Strength Characteristics of Portland Cement Concrete
Eric Opoku Amankwah,
Mark Bediako,
C. K. Kankam
Issue:
Volume 3, Issue 6, November 2014
Pages:
410-419
Received:
12 December 2014
Accepted:
24 December 2014
Published:
6 January 2015
Abstract: The paper presents results of a study on concrete mixes containing two types of calcined clay pozzolanas obtained from Mankranso and Tanoso for structural application. Mankranso sample is labeled Type I whilst Tanoso also labeled as type II.Both clay samples were analysed to determine their physical and geotechnical properties whilst the chemical composition of the calcined clay samples analysed. Portland cement was replaced with 0%-25%Type I and 0-30% of Type II pozzolanas to formulate binder pastes and concretes. Setting times and normal consistency test were determined on the formulated binder paste. Three grades of concrete (25N/mm2, 30N/mm2 and 40N/mm2) containing pozzolana were prepared and their workability, density, compressive strength and flexural strength investigated against the plain concrete. Concretes with clay pozzolana had delayed setting times and lower densities. They also exhibited a reduction in compressive and tensile strength development at early age (7 days), with an average drop of 6 percent in compressive strength for all grades. However, the compressive and tensile strengths beyond 28 days notably exceeded the control un-blended mixes. This study recommends up to 20% clay pozzolana content of both Types I and II for concrete grades of 25N/mm2, 30N/mm2 and 40N/mm2.
Abstract: The paper presents results of a study on concrete mixes containing two types of calcined clay pozzolanas obtained from Mankranso and Tanoso for structural application. Mankranso sample is labeled Type I whilst Tanoso also labeled as type II.Both clay samples were analysed to determine their physical and geotechnical properties whilst the chemical c...
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An Experimental Study on the Mechanical Characteristics of Low Alloy Carbon Steels for Better Performance of Traditional Farm Implements in Ethiopia
Belete Kefarge,
Adhena Ayaliew Werkneh,
Asmamaw Tegegne,
Fikadu Gashaw
Issue:
Volume 3, Issue 6, November 2014
Pages:
420-430
Received:
3 January 2015
Accepted:
10 January 2015
Published:
21 January 2015
Abstract: For most developing countries, including Ethiopia Agriculture is the backbone of their economy. Due to lack of effective farm implements, theses country’s population has been suffering on food shortage. Hence, the major objective the study is to improve the mechanical properties and abrasion resistance of traditional farm implements. To achieve the intended objectives of the study, Investigation was conducted on the mechanical and wear characteristics of steel samples for better performance of farm implements subjected to packed carburization treatment using wood coal as the carburizer, carburized at 850 °C, 900 °C and 950 °C, soaked at the carburizing temperature for 1:50 hrs followed by quenched with water. At the first the test specimen for analysis of different mechanical and wear characteristics of various local farming tools like abrasive wear, toughness, tensile strength, abrasive wear and hardness were prepared as per ASTM standard. The test specimens that was prepared for this purpose was subjected to destructive mechanical test before and after carburization process. From the data obtained, ultimate tensile strength, percent elongation, percent reduction in area, modulus of elasticity, Rockwell hardness, impact toughness, and abrasive wear were calculated. The destructive mechanical test results are compared before and after carburization process in order to see the impact of pack carburization and carburizing temperature on the performance (life cycle )of the traditional farm implements. It was observed that the mechanical properties of steel samples were found to be strongly influenced by the process of carburization, carburizing temperature and soaking time at carburizing temperature. It was concluded that the sample carburized at 950 °C soaked for 1:50 hrs followed by water quenching gives best result than the other samples. Since pack carburizing enhance the hardness, tensile strength, abrasion resistance, the farm implement manufacturing company has been recommended to carburize these farm implement.
Abstract: For most developing countries, including Ethiopia Agriculture is the backbone of their economy. Due to lack of effective farm implements, theses country’s population has been suffering on food shortage. Hence, the major objective the study is to improve the mechanical properties and abrasion resistance of traditional farm implements. To achieve the...
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