Object:Geopolymers mixes were fabricated from Metakaolin (MK) and Blast Furnace Slag (BFS) waste material in the presence of sodium hydroxide and sodium silicate which were used as alkali activators. To optimize the suitable amount of slag, eleven batches were designed, mixed and homogenized for 30 min.Method:To determine the suitable amount of liquid required for pasting, normal consistency and setting time were determined. The physico-mechanical properties at different curing agesi.e. 3, 7, 28 and 90 days, were determined. X-ray diffraction and scanning electron microscope were used to investigate phase composition and microstructure.Result:To guarantee forming geopolymer gel and to check its amount, HCl extraction test was performed. Salicylic acid/methanol extraction was also performed to verify the presence and amount of Calcium Silicate Hydrate (CSH). The results revealed that calcium-rich slag (BFS) accelerated the hardening process and decreased the alkaline liquid consistency. For geopolymer without BFS, two phases, namely; un-reacted metakaolin and geopolymer gel were formed. For geopolymers with BFS, three phases were formed, namely; un-reacted metakaolin, geopolymer gel and CSH with aluminum substitution (CASH) gel. The bulk density was increased with increasing BFS and curing time. The strength was increased with increasing of BFS, reaching its maximum (about 120 MPa) for the specimen containing 70% slag, cured for 28 days.
Objective:Cinnamic acid and its derivatives have a numerous potential applications in many different fields such as pharmacy, organic “building blocks”, and corrosion inhibitors.Method:It is well-known that Verley-Doebner modification is a high efficient method for the preparation of cinnamic acid derivaties, especially with the compounds containing electron-donating subtituents at para position in aromatic ring. In this paper, 4-ethoxy-cinnamic acid was synthesized according to Verley-Doebner reaction with the use of pyrine acting as catalyst and solvent. The effect of the β-alanine concentration on the conversion of the starting material of 4-ethoxy-benzaldehyde was thoroughly investigated using high performance liquid chromatography. The results showed that consuming of 8% of β-alanine would convert 100% of 4-ethoxy-benzaldehyde to 4-ethoxy-cinnamic acid.Result:The structure of the obtained 4-ethoxy-cinnamic acid was also confirmed using Fourier transform infrared spectroscopy, Raman spectroscopy, and Gas chromatography-Mass spectroscopy.Cinnamic acid and its derivatives have numerous potential applications in many different fields such as pharmacy, organic “building blocks”, and corrosion inhibitors. It is well-known that Verley-Doebner modification is a high efficient method for the preparation of cinnamic acid derivaties, especially with the compounds containing electron-donating subtituents at para position in aromatic ring. In this paper, 4-ethoxy-cinnamic acid was synthesized according to Verley-Doebner reaction with the use of pyrine acting as catalyst and solvent. The effect of the β-alanine concentration on the conversion of the starting material of 4-ethoxy-benzaldehyde was thoroughly investigated using high performance liquid chromatography. The results showed that consuming 8% of β-alanine would convert 100% of 4-ethoxy-benzaldehyde to 4-ethoxy-cinnamic acid. The structure of the obtained 4-ethoxy-cinnamic acid was also confirmed using Fourier transform infrared spectroscopy, Raman spectroscopy, and Gas chromatography-Mass spectroscopy.
Objective:The present study is deals with the green synthesis of silver (AgNPs), iron oxide (α-Fe2O3NPs) and core-shell (Ag-α-Fe2O3CNPs) nanoparticles using the aqueous extract ofAlstonia scholariswithout any catalyst, template or surfactant or any intermediate under ultrasound cavitation technique. The purpose was to facilitate the high level of dispersion with increase in rate of reaction. Further AgNPs and α-Fe2O3NPs were used to synthesis Ag-Fe2O3CNPs in aqueous extract ofAlstonia scholarisunder controlled ultrasound cavitation technique.Methods:The size of AgNPs and Ag-Fe2O3CNPs can be tuned by optimizing various reaction parameters. UV-visible, X-ray diffraction spectroscopy (XRD), Transmission electron microscopy (TEM), Field emission scanning electron microscope (FE-SEM) and Fourier transform infra-red spectroscopy has been used for the characterization of silver and core shell Ag@Fe2O3nanoparticles. TEM images clearly show the formation of core shell nanoparticles with spherical morphology.Result:Fourier transform infra-red spectroscopy analysis revealed that carbohydrate, polyphenols, and protein molecules were involved in the synthesis and capping of silver, iron oxide and Ag@Fe2O3CNPs.
Objective:In this study, electrochemical measurements were used to characterize Anhydrous Tricalcium Phosphate (ATP) as a corrosion inhibitor for mild steel in 1.0 M HCl.Method:The potentiodynamic polarization curves indicated that the ATP reacts as an anodic type inhibitor. In addition, it has been found that the electrochemical impedance confirms the inhibitor character of ATP obtained by the potentiodynamic polarization curves where the inhibition efficiency increases by its concentration to reach a maximum of 93.79 % at 10-4M. The temperature solution influence indicated that the corrosion rate increases with temperature while the inhibitor acts actively. Thermodynamic adsorption and activation parameters indicated that the ATP acts by physical adsorption on the metallic surface with an endothermic process of metal dissolution.Result:Additionally, it was found that the adsorption of ATP molecules obeyed to the Langmuir isotherm. Surface analyses via scanning electron microscopy (SEM) was used to investigate the morphology of mild steel before and after immersion in 1.0 M HCl solution without and with 10-4M of ATP. It is revealed that the ATP acted by the formation of a protective layer on the mild steel.
Background:The increasing use of composite structures with a high stiffness-to-weight ratio in commercial vehicles has brought about a reduction in fuel consumption but, on the other hand, has significantly increased noise transmission particularly in case of thin and lightweight structures. Noise is a primary issue for commercial vehicles, such as airplanes, helicopters and cars. The present research deals with the use of smart materials, as Shear-Thickening Fluids (STF, or dilatants) in view of manufacturing elements with increased sound insulation properties.Methods:The response of a sandwich material with the STF core was investigated both experimentally and numerically, by choosing the Sound Transmission Loss (STL) of the composite structure as the figure of merit.The experimental investigation was focused on the manufacturing of a sandwich structure made of metallic skins and a STF core that was successively characterized by sound insertion loss measurement.The numerical investigation was carried out by using a Generalized Transfer Matrix Method (GTMM) and a Statistical Energy Analysis (SEA) in view of selecting the fluid capable of granting the highest acoustic transmission loss.Results:Finally, the test results were compared to the numerical results, showing a noticeable agreement. The used STF showed increasing viscosity at increasing shear rates.
Aim and Objectives The ultrafine powders of the perovskite-like layered AII3LaM3O12 (AII = Sr, Ba; M = Nb, Ta) compounds have been synthesized by heat treatment of co-precipitated hydroxy-carbonates. The luminescence of these compounds is reported for the first time. Methods: Luminescence spectra of all studied compounds are complex and contain two main wide bands with maxima near 2.9 and 2.5 eV. These luminescence bands were assigned to radiation electron transitions in the MoO67- molecular groups of different symmetry located in the various lattice positions. Conclusion: The energy levels scheme of the MoO67- group and related radiation and absorption transitions had been proposed.
With the advent of the new year 2018, the Open Access Journal of Materials Science has begun new adventures in expanding its horizons in forever widening fields of important academic and industrial interests.Material Science, has over the last few years been one major targets with solar materials, graphenes, fullerenes, superconductors and energy sources being some of the growing specialisations in the field.In 2017, the Journal also revitalised its Editorial Board membership with a more integrated and active participation in expanding its worldwide coverage of topics by appointing many new highly active and prestigious scientists from across the Globe.Within this context, the Board has also acquired many new and young highly active professionals to explore many of the new and growing topical fields in energy, environmental, oil, gas, new plastics, metals and crystallography, ceramics and cement and medical materials.These are, but a few of the many expanding specialisations and Industries which the Open Access Journal is aiming to be the foremost runners.I welcome our new board members and authors, industries, societies and academic institutions to join us in this new venture and look forward to your co-operation with any new positive ideas.
Objective:This research aims to determine corrosion behavior of SS316L biomaterial metals after plasma nitriding process. Methods:The plasma nitriding process on the surface of SS316L was performed at 350oC, 400oC, 450oC, 500oC, 550oC and 1.8 mbar nitrogen gas pressure for 3 hours.The surface Nitrogen concentration level distribution from the surface was examined using Energy Dispersive X-ray Spectroscopy, the phases formed after nitriding process were determined using X-ray Diffraction.The corrosion resistance was investigated using three-electrode cell polarization method. Result:The results showed that the percentage of nitrogen concentration atoms on the surface of the SS316L after plasma nitriding process was in range of 7.61-21.73%, in which the highest number 21.73% occurred at 500oC.Metal nitride formed on the surface of SS316L for all temperature variations are Fe4N, CrN and β-Cr2N phases were formed after nitriding process.Optimum corrosion resistance (8.21 x 10-4 mm/yr) occurs at 350oC.
Objective and Method: In this paper,the experiment proved that shot noise is suppressed by Fermi and Coulomb interaction correlation. Meanwhile, the establishment of shot noise suppression factor (Fano) in ballistic transport nano-MOSFETs the Coulomb interaction correlation and the combination of the two effects are derived from separately considering the Fermi interaction correlation. And on this basis the variation of Fano with voltage, doping concentration and temperature are investigated. Result: The result we obtained which considered the combination of the two effects is in good agreement with experimental studies in the research papers, thus getting a theoretical explanation for the variation of the suppression factor with the bias voltage. Meanwhile, the suppression factor model is suitable for nano-MOSFET.
Objective: To develop more green polymer composites and further know the performance of green composites, the composites based on green poly(L-lactic acid) (PLLA) and starch were fabricated by a counter-rotating mixer. And effect of starch on the fluidity and nucleating performance of PLLA was investigated using melt index instrument, optical depolarizer and wide angle X-ray diffraction instrument, respectively. Method and Conclusion: The fluidity of PLLA/starch composites showed that, compared to the neat PLLA, the addition of starch made the fluidity of PLLA increase significantly and the melt mass flow rate of PLLA/5%starch sample had the maximum value 13.36 g/10min. In addition, the introduction of starch could also increase the crystallization rate of PLLA through isothermal crystallization measurement and x-ray diffraction analysis, the maximum value of crystallization rate of PLLA/starch composites appeared in low crystallization temperature zone, and 10 wt% starch could make the t1/2 of PLLA decrease from 3999.4s to 421.4s.
It is easy for composite laminates to be damaged by relative lower velocity impact which could give rise to internal delamination that will strongly weaken the compressive strength of laminates. In order to predict the occurrence of matrix failure, the elastic-brittle behaviors of fiber-reinforced composites were modeled constitutively by an anisotropic damage model. The dynamic tensile testing was performed at a constant velocity of 2 mm/min until the sample broke to achieve the mechanical parameters of E-glass reinforcements. The elastic constitutive equation and the constitutive damage model were obtained on basis of the fundamental theory of mechanics about the orthotropic constitutive of reinforcements. The methodology for this constitutive model which is developed by Hashin considered both the effect of fiber and matrix failure. Then, the developed constitutive equations were incorporated into the FE (finite element) codes, ABAQUS, through the user subroutine module to simulate the process of projectile impacting GFRP composite laminates. The results show that the material deformation reaches a maximum at 24 μs, then occurs rebound with the increase of the time. The stress of reinforcements traverse section linearly increases outward from 0 MPa to 509.8 MPa. Material damage area increases with the prolonging of time, and for a fixed time, material damage gradually increases from the edges to the center and reaches a constant value of 1, which means the rupture of the damage process.
A facile and efficient method was developed for the synthesis of highly active palladium nanoparticles (PdNPs) by microwave-assisted chemical reduction. The PdNPs with different morphology were prepared with or without KBr (capping agent) using ethylene glycol (EG) and citric acid (CA) as reducing agent in the presence of polyvinylpyrrolidone (PVP), respectively. The as-prepared PdNPs were characterized by (UV-Visible Spectrophotometer) UV-Vis, transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The results showed that the PdNPs reduced by EG without KBr (PdNPs-EG) has smaller particle size than other PdNPs. The remarkable catalytic activity of the PdNPs catalysts are obtained using a low amount of PdNPs (0.1 mmol‰) using K2CO3 as base and EtOH/H2O as solvent toward Suzuki coupling reactions of aryl bromides and phenylboronic acid for 15 min.
The goal of this work was to study the non isothermal and isothermal crystallization behavior of Poly(L-lactic acid) (PLLA) with melamine (TP) through differential scanning calorimeter and optical depolarizer. The study of the crystallization behavior of PLLA/TP composites indicated that TP could promote the crystallization of PLLA. The half time of overall crystallization of PLLA with 1.5 wt% TP, compared with the neat PLLA, gave rise to a decrease from 3999.44 s to the minimum value 228 s at 100 °C. In addition, the cooling rate also affected significantly the crystallization behavior of PLLA. The melting behavior of PLLA/TP composites exhibited a complicated and different melting process after cooling crystallization, and the increasing of TP content made melt mass flow rate of PLLA firstly decrease, then increases.
Cobalt, nickel and iron-based alloys containing 25wt.%Cr and strengthened either by chromium carbides or by HfC were oxidized at 1000, 1100 and 1200°C to obtain external oxide scales. The spallation of these oxides during the post-oxidation cooling was studied by exploiting the cooling part of the thermogravimetry curves. The best resistant alloys against scale spallation were the iron-based alloys which did not lose oxide. The nickel-based alloys well behaved too. The worst alloys were the cobalt alloys, principally due to the complex composition of the oxide scales. Beside the base element, the thickness of the oxide was also identified as a major parameter. The presence of Hf with contents much higher than usual was also beneficial for the resistance against spallation.
In this paper, the mechanical structure of an underactuated end-effector manipulator for apple-picking is presented. The structure is consisted of three identical fingers which are driven by one motor. Each finger is formed by three joints which are connected with connecting bar and gears. With operation of grasp and twist executed by the driven fingers, apple-picking action completed. Mathematical model of the mechanical structure is proposed. Kinematics simulation & optimization software which have a Human-Computer Interaction interface is developed with Visual Basic visualization platform. Parameters which affect enveloping space mostly are analyzed. With processing and analyzing data which get from the software, a set of optimum structure parameters are obtained. A sample machine of the End-effector Manipulator which is used for testing purpose is designed according to the optimum structure parameters.
In the paper, the folded-cascode low-noise operational amplifier (LNA) with constant-gm is proposed and analyzed. The channel-length split technique adopted to expand ratio of W/L of the differential pair transistor to improve the performance of LNA for the gain bandwidth product, noise and offset voltage. The channel-length split method is separated differential input transistor into 2 transistors in series. The area of the transistor (W, L) can be properly increased to effectively decrease the flick noise. The double indirect-frequency compensation technique and the clamping circuit are adopted in amplifier to increase the bandwidth. The proposed two sets input differential pair can be provided a constant-gm value and rail-to-rail swing during the operating region. The floating-point structure is used to reach rail-to-rail swing at output stage. Simulation results show that the gain, constant-gm in input stag, noise, offset-voltage, PSRR, CMRR and ICMR of amplifier are improved. The characteristics of LNA are successfully verified by the TSMC 0.35um 2P4M CMOS technology. There have a great potential in the VLSI implementation used in the portable electronic and bio-medicine product applications.
We investigate the longitudinal and transverse polarized cross-sections of the leptoproduction of the ρ meson in the high energy limit. Our model is based on the computation of the impact factor γ (λγ )→ ρ(λρ ) using the twist expansion in the forward limit which is expressed in the impact parameter space. This treatment involves in the final stage the twist 2 and twist 3 distribution amplitudes (DAs) of the ρ meson and the dipole scattering amplitude. Taking models that exist for the DAs and for the dipole cross-section. We get a phenomenological model for the helicity amplitudes. We compare our predictions with HERA data and get a fairly good description for large enough virtualities of the photon. PACS number(s): 13.60.Le, 12.39.St, 12.38.Bx.
Nanocontact printing using hydrogen silsesquioxane (HSQ) soft stamps is studied for nanobio device fabrications in this work. The stamps with designed linewidth 80-200 nm were fabricated by low-dose e-beam lithography on HSQ films. The contact printing technique by using aminosilane as the ink on O2plasma treated HSQ/Si substrates was developed. The plasma treatment, stamping force and stamping time were manipulated, and afterwards the transferred patterns were examined by the utilization of atomic force microscope and scanning electron microscope. Experimental results demonstrate that the nano-features on the HSQ stamps can be successfully transferred onto the substrates and passed a 3M tape peeling test under specific conditions in the range of 100-200 W O2plasma treatment for 30 s. Nanolines with printed linewidth 97-205 nm were obtained. The nanopatterning of an antibody affinipure goat anti-mouse IgG(H+L) was also demonstrated onto the transferred aminosilane pattern surfaces for bio-device fabrication.
