Advances in Materials Science and Engineering http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Reduced-Pressure Boiling Extraction of Oleuropein Coupled with Ultrasonication from Olive Leaves (Olea europaea L.) Thu, 03 Sep 2015 12:01:36 +0000 http://www.hindawi.com/journals/amse/2015/719485/ Oleuropein was extracted from Frantoio olive leaves using reduced-pressure boiling extraction coupled with ultrasound-assist (URPE). Four important factors, extraction temperature, ultrasonic power, ethanol concentration, and the ratio of solid to liquid, were selected to carry out the response surface methodology (RSM) for seeking optimal conditions on high oleuropein extraction yield at different levels. Box-Behnken design was employed to investigate the effects of the four factors on it. The results showed that the ratio of solid to liquid was the most significant factor of all on oleuropein yield. The optimal operation conditions were obtained as follows: ethanol concentration 75% (v/v), extraction temperature 53°C, ultrasonic power 600 W, and the ratio of solid to liquid 1 : 31. Under these optimal conditions, oleuropein extraction yield was 7.08%, which was close to the predicted value 7.121%. The scanning electron microscope (SEM) images of olive leaves after extraction were provided as well. It was seen that, compared with the untreated leaves, URPE could effectively break cells within the olive leaves. Pu-jun Xie, Li-xin Huang, Cai-hong Zhang, Feng You, Cheng-zhang Wang, and Hao Zhou Copyright © 2015 Pu-jun Xie et al. All rights reserved. Microwave Assisted Hydrolysis of Holocellulose Catalyzed with Sulfonated Char Derived from Lignin-Rich Residue Thu, 03 Sep 2015 09:47:02 +0000 http://www.hindawi.com/journals/amse/2015/106137/ A microwave assisted green process has been developed for production of sugars through liquefying holocellulose catalyzed with sulfonated char derived from the lignin-rich residue produced during pretreatment of lignocellulose. Various reaction parameters including the hydrolysis temperature, hydrolysis time, catalyst content, and the ratio of water to feedstock were evaluated. The maximum sugars yield of 82.6% (based on the dry mass of holocellulose) was obtained under the optimum reaction conditions. The sulfonated char showed superior catalytic performance to that of dilute sulfuric acid in converting holocellulose into sugars under microwave irradiation. Kui Wang, Xinfeng Xie, Zhan Si, Jianchun Jiang, and Jingxin Wang Copyright © 2015 Kui Wang et al. All rights reserved. Effect of Heating at Oven-Dry State on Steam Treated Bamboo Powder Thermal Fluidity Thu, 03 Sep 2015 09:29:53 +0000 http://www.hindawi.com/journals/amse/2015/579659/ In hot molding processes of woody material, it is important to understand the effect of oven-dry heating on the property of woody biomass material, such as thermal fluidity. In this study, thermal flow tests of untreated and steam treated bamboo powder were conducted to investigate the effects of heating at an oven-dry state on thermal fluidity. The test temperature was set to 200°C. Before the thermal flow test, powder was dry-heated in a capillary rheometer at 200°C with a variable heating time. Thermogravimetry was conducted to understand the thermal changes of the powder during an increasing temperature and constant temperature. Fluidity of untreated powder was improved with a short dry-heating but decreased with a long dry-heating. In contrast, steam treated powder fluidity was high compared to untreated one, but its fluidity did not improve from dry-heating. From these thermogravimetry results, the chemical changes associated with component volatilization relate with the thermal fluidity. Therefore, the decrease in fluidity from dry-heating occurred because fluidity related components escape from the powder through volatilization. S. Kajikawa and T. Iizuka Copyright © 2015 S. Kajikawa and T. Iizuka. All rights reserved. Effects of Screen Size on Biochemical Conversion of Big Bluestem Biomass for Biofuel Production Thu, 03 Sep 2015 08:52:33 +0000 http://www.hindawi.com/journals/amse/2015/947350/ Biomass size reduction is the first step for biofuel production from cellulosic biomass through biochemical pathway, and it is usually performed on a mill with screen installed to control the size of the produced particles. The absence of in-depth knowledge about the effects of screen size throughout the biochemical conversion of cellulosic biomass makes it difficult to choose the screen size to conduct biomass size reduction to minimize the energy consumption on mills, maximize the cellulose recovery rate after pretreatment, and maximize the enzymatic hydrolysis efficiency. The objective of this work is to address this issue by generating new knowledge on the effects of screen size in these three processes: size reduction, pretreatment, and enzymatic hydrolysis in conversion of big bluestem biomass for biofuel production. Four screen sizes used in this study were 1, 2, 4, and 8 mm. It was found that using a larger screen size saved energy in biomass size reduction on a knife mill. Moreover, particles produced with larger screen sizes achieved higher cellulose recovery rate after pretreatment, higher enzymatic hydrolysis efficiency, and higher total sugar yield. Xiaoxu Song, Meng Zhang, Ke Zhang, Z. J. Pei, and Donghai Wang Copyright © 2015 Xiaoxu Song et al. All rights reserved. Effect of Keratin Structures from Chicken Feathers on Expansive Soil Remediation Mon, 31 Aug 2015 13:32:56 +0000 http://www.hindawi.com/journals/amse/2015/907567/ Chicken feathers are composed mainly of avian keratin, a fibrillar protein with a complex structure, and important properties such as durability, hydrophobicity, being chemically unreactive, and depending on the specific function can change its morphological and inner structure. This study takes advantage of these features and for the first time the use of keratin from chicken feathers to modify characteristics on expansive soils is reported. Swelling characteristics of remolded expansive soil specimens were studied through varying the percentage of keratin fiber content using 0.25, 0.50, 1.00 and 3.00 wt%. One-dimensional swell-consolidation tests were conducted on oedometric specimens, specific surface area was determined using methylene blue, and degree of saturation was also analyzed. Finally random distribution and interaction between keratin structures and soil were studied by scanning electron microscopy. The results show that randomly distributed fibers are useful in restraining the swelling tendency of expansive soils. The maximum reduction of pressure (43.99%) due to swelling is achieved by reducing the void ratio, which can be reached with the addition of chicken feather keratin structures to the expansive soil. Finally, the mechanism by which discrete and randomly distributed fibers reduce swelling pressure of expansive soil is explained. Elda Montes-Zarazúa, Arturo Colín-Cruz, María de la Luz Pérez-Rea, Miguel de Icaza, Carlos Velasco-Santos, and Ana Laura Martínez-Hernández Copyright © 2015 Elda Montes-Zarazúa et al. All rights reserved. Experimental Study on Unconfined Compressive Strength of Basalt Fiber Reinforced Clay Soil Thu, 27 Aug 2015 11:49:22 +0000 http://www.hindawi.com/journals/amse/2015/561293/ In order to study the mechanism and effect of basalt fiber reinforced clay soil, a series of unconfined compressive strength tests conducted on clay soil reinforced with basalt fiber have been performed under the condition of optimum water content and maximum dry density. Both the content and length of basalt fiber are considered in this paper. When the effect of content is studied, the 12 mm long fibers are dispersed into clay soil at different contents of 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0.30%, and 0.35%. When the effect of length is researched, different lengths of basalt fibers with 4 mm, 8 mm, 12 mm, and 15 mm are put into soil at the same content of 0.05%. Experimental results show that basalt fiber can effectively improve the UCS of clay soil. And the best content and length are 0.25% and 12 mm, respectively. The results also show that the basalt fiber reinforced clay soil has the “poststrong” characteristic. About the reinforcement mechanism, the fiber and soil column-net model is proposed in this paper. Based on this model and SEM images, the effect of fiber content and length is related to the change of fiber-soil column and formation of effective fiber-soil net. Lei Gao, Guohui Hu, Nan Xu, Junyi Fu, Chao Xiang, and Chen Yang Copyright © 2015 Lei Gao et al. All rights reserved. Effect of Relative Humidity on the Tribological Properties of Self-Lubricating H3BO3 Films Formed on the Surface of Steel Suitable for Biomedical Applications Wed, 26 Aug 2015 07:11:45 +0000 http://www.hindawi.com/journals/amse/2015/436597/ The effect of environmental humidity on the self-lubricating properties of a thin film of boric acid (H3BO3) was evaluated. H3BO4 films were successfully formed on the surface of AISI 316L steel. The study was conducted on AISI 316L steel because of its use in biomedical applications. First, the samples were exposed to boriding to generate a continuous surface layer of iron borides. The samples were then exposed to a short annealing process (SAP) at 1023 K for 5 min and cooled to room temperature while controlling the relative humidity (RH). Five different RH conditions were tested. The purpose of SAP was to promote the formation of a surface film of boric acid from the boron atoms present in the iron boride layers. The presence of the boric acid at the surface of the borided layer was confirmed by Raman spectroscopy and X-ray diffraction (XRD). The self-lubricating capability of the films was demonstrated using the pin-on-disk technique. The influence of RH was reflected by the friction coefficient (FC), as the samples cooled with 20% of RH exhibited FC values of 0.16, whereas the samples cooled at 60% RH showed FC values of 0.02. E. Hernández-Sanchez, A. Chino-Ulloa, J. C. Velazquez, H. Herrera-Hernández, R. Velázquez-Mancilla, and R. Carrera-Espinoza Copyright © 2015 E. Hernández-Sanchez et al. All rights reserved. Effect of Eu3+ Concentration on the Luminescent Properties of SrTiO3 Phosphors Prepared by Pressure-Assisted Combustion Synthesis Tue, 25 Aug 2015 12:06:35 +0000 http://www.hindawi.com/journals/amse/2015/291230/ This work presents the structural, morphological, and luminescent characterization of pure SrTiO3 and SrTiO3:Eu3+ powders doped with different europium atomic concentrations from 3.0 to 7.0 a.t.%. Those phosphors were prepared by pressure-assisted combustion synthesis using titanium oxide as precursor and were subjected to postannealing at 1200°C. XRD measurements indicated that undoped and Eu3+ doped samples presented a single cubic crystalline phase and SEM images demonstrated that we have particles with sizes in the range of 0.2 µm–1.0 µm. Moreover, the size of the grains increases as the content of Eu3+ dopant increases. A strong red emission from Eu3+ ions was obtained by photoluminescence under excitation at 396 nm and confirmed by cathodoluminescence. All those results indicate that our red phosphors could be useful for potential applications in solid state lighting and field emission displays. C. R. García, J. Oliva, M. T. Romero, R. Ochoa-Valiente, and L. A. Garcia Trujillo Copyright © 2015 C. R. García et al. All rights reserved. Effect of Nitrogen Content on Hot Deformation Behavior and Grain Growth in Nuclear Grade 316LN Stainless Steel Tue, 25 Aug 2015 10:34:34 +0000 http://www.hindawi.com/journals/amse/2015/427945/ 316LN stainless steel with 0.08%N (08N) and 0.17%N (17N) was compressed at 1073–1473 K and 0.001–10 s−1. The hot deformation behavior was investigated using stress-strain curve analysis, processing maps, and so forth. The microstructure was analyzed through electron backscatter diffraction analysis. Under most conditions, the deformation resistance of 17N was higher than that of 08N. This difference became more pronounced at lower temperatures. The strain rate sensitivity increased with increasing temperature for types of steel. In addition, the higher the N content, the higher the strain rate sensitivity. Hot deformation activation energy increased from 487 kJ/mol to 549 kJ/mol as N concentration was increased from 0.08% to 0.17%. The critical strain for initiation of dynamic recrystallization was lowered with increasing N content. In the processing maps, both power dissipation ratio and unstable region increased with increasing N concentration. In terms of microstructure evolution, N promoted dynamic recrystallization kinetic and decreased dynamic recrystallization grain size. The grain growth rate was lower in 17N than in 08N during heat treatment. Finally, it was found that N favored twin boundary formation. Ming-wei Guo, Zhen-hua Wang, Ze-an Zhou, Shu-hua Sun, and Wan-tang Fu Copyright © 2015 Ming-wei Guo et al. All rights reserved. Mechanical Parameters Effects on Acoustic Absorption at Polymer Foam Sun, 23 Aug 2015 14:04:05 +0000 http://www.hindawi.com/journals/amse/2015/896035/ Polymer foams have acoustic absorption properties that play an important role in reducing noise level. When the skeleton is set to motion, it is necessary to use generalized Biot-Allard model which takes into account the deformation of the skeleton and the fluid and the interactions between them. The aim of this work is to study the quality of acoustic absorption in polyurethane foam and to show the importance of the structural vibration of this foam on the absorption by varying mechanical parameters (Young’s modulus , Poisson’s coefficient , structural damping factor , and the density ). We calculated the absorption coefficient analytically using classical Biot formulation (, ) and numerically using Biot mixed formulation (, ) in 3D COMSOL Multiphysics. The obtained results are compared together and show an excellent agreement. Afterwards, we studied the effect of varying each mechanical parameter independently on the absorption in interval of ±20%. The simulations show that these parameters have an influence on the sound absorption around the resonance frequency . Lyes Dib, Samia Bouhedja, and Hamza Amrani Copyright © 2015 Lyes Dib et al. All rights reserved. Analysis Technique on Water Permeability in Concrete with Cold Joint considering Micro Pore Structure and Mineral Admixture Thu, 20 Aug 2015 13:12:54 +0000 http://www.hindawi.com/journals/amse/2015/610428/ Cold joint in concrete due to delayed concrete placing may cause a reduced shear resistance and increased water permeation. This study presents an analytical model based on the concept of REV (Representative Element Volume) to assess the effect of water permeability in cold joint concrete. Here, OPC (Ordinary Portland Cement) concrete samples with cold joint are prepared and WPT (Water Permeability Test) is performed on the samples cured for 91 days. In order to account for the effect of GGBFS (Granulated Ground Blast Furnace Slag) on water permeability, concrete samples with the same W/B (Water to Binder) ratio and 40% replacement ratio of GGBFS are tested as well. Utilizing the previous models handling porosity and saturation, the analysis technique for equivalent water permeability with effective cold joint width is proposed. Water permeability in cold joint increases to 140.7% in control case but it decreases to 120.7% through GGBFS replacement. Simulation results agree reasonably well with experimental data gathered for sound and cold joint concrete. Se-Jin Choi, Suk-Pyo Kang, Sang-Chel Kim, and Seung-Jun Kwon Copyright © 2015 Se-Jin Choi et al. All rights reserved. A Study of Isothermal Curing of PMI Using DMA Wed, 19 Aug 2015 10:41:45 +0000 http://www.hindawi.com/journals/amse/2015/695286/ The isothermal curing of polymethacrylimide (PMI) is studied through the use of dynamic mechanical analysis (DMA). Based on the growth rate of measured dynamic mechanical property, the relative conversion is defined to investigate the evolution of storage modulus at different curing temperatures. Hsich’s nonequilibrium thermodynamic fluctuation theory, Avrami equation, and isoconversional methods are used to analyze isothermal cure kinetics of PMI. The results show that there are different increase modes of at low temperature range and high temperature range, respectively. In low temperature range, the relative conversion curves include a transitional stage which is found to be strongly frequency-dependent, but this stage is not observed in the relative conversion curve in high temperature range. During the isothermal curing process, the relative evolution of can be described by Hsich’s nonequilibrium thermodynamic fluctuation theory and Avrami equation. Moreover, the values and evolutions of activation energy are different in two temperature ranges, which suggest that the curing mechanism probably has changed. Jing Zhang, Rui Ye, Jun Zou, Jijun Tang, and Hongliang Wang Copyright © 2015 Jing Zhang et al. All rights reserved. Influence of Indentation on the Fatigue Strength of Carbonitrided Plain Steel Tue, 18 Aug 2015 12:22:42 +0000 http://www.hindawi.com/journals/amse/2015/492693/ To study the influence of indentation on the fatigue strength of untreated and carbonitrided specimens of S38C steel, the fatigue limit of specimens with and without indentations was tested. Fracture surfaces were observed using scanning electron microscopy (SEM). The results show that the fatigue strength of the untreated specimen decreases with increasing dimension of indentation, without significant difference compared to the predicted results. Compared to the fatigue limit of the untreated specimen, those of the carbonitrided specimen and the carbonitrided specimen whose compound layer was polished were improved by 12% and 40%, respectively. The fatigue strength of the carbonitrided specimen decreased sharply with increasing indentation size because of the presence of microcracks in the compound layer. When the compound layer was removed, the fatigue limit was observed to be less sensitive to indentation than that of the carbonitrided specimen. Jiewei Gao, Guangze Dai, Junwen Zhao, Hengkui Li, Lei Xu, and Zhenyu Zhu Copyright © 2015 Jiewei Gao et al. All rights reserved. The Sheet Metal Formability of AA-5083-O Sheets Processed by Friction Stir Processing Tue, 18 Aug 2015 06:42:20 +0000 http://www.hindawi.com/journals/amse/2015/716165/ The aim of this study is to determine the sheet metal formability of AA-5083-O sheets processed by the Friction Stir Processing (FSP). The FSP process was studied and a FSP tool was built. Processing quality was verified by the metallography in the processing region, which established the voids presence. Tensile tests were carried out on FSP and non-FSP specimens, and the results showed that FSP specimens have 30% greater resistance than non-FSP ones. The formability of FSP sheets was produced in MSC-MARC and Abaqus and these software products were compared by using the nonlinear FEM code. The Forming Limit Diagram was built with the results from both software products. A device to process FSP sheet metals was developed and the sheets were processed to validate the results from the software. The tools made for the bulge tests were circular and ellipse-shaped. After the bulge tests, the commercial sheets showed close approximation to those obtained from the software. The FSP sheets broke when inferior pressure was applied because of the defects in the FSP process. The results of the FSP presented the same formability of commercial sheets, however, with 30% greater strength. G. F. Miori, E. C. Bordinassi, S. Delijaicov, and G. F. Batalha Copyright © 2015 G. F. Miori et al. All rights reserved. Influence of Diatomite and Mineral Powder on Thermal Oxidative Ageing Properties of Asphalt Thu, 13 Aug 2015 13:17:17 +0000 http://www.hindawi.com/journals/amse/2015/947834/ Ageing of asphalt affects the performances of asphalt pavement significantly. Therefore, effects of diatomite and mineral powder on ageing properties of asphalt were investigated systematically in order to improve the antiageing property of mixture. Thin film oven test (TFOT) was used to conduct the short term ageing in laboratory. Softening points, penetrations, force ductility, low temperature creep properties, and viscosities of asphalt mastics were tested before and after TFOT, respectively. Results indicated that percent retained penetration (PRP) increased with the increasing of fillers. Increment of softening point (), ductility retention rate (DRR), deformation energy ageing index (JAI), and viscosity ageing index (VAI) of asphalt mastics nonlinearly decreased with the increasing of fillers. Ageing of asphalt was reduced by diatomite and mineral powder. And the antiageing effect of diatomite was better than that of mineral powder as a result of its porous structure. It is suggested that the mineral powder could be reasonably replaced by diatomite in order to reduce thermal oxidative ageing of asphalt mixture. The optimal content of diatomite 12.8% is also suggested for engineering. Yongchun Cheng, Jinglin Tao, Yubo Jiao, Qinglin Guo, and Chao Li Copyright © 2015 Yongchun Cheng et al. All rights reserved. Room-Temperature Synthesis of Ni Nanoparticles as the Absorbent Used for Sewage Treatment Thu, 13 Aug 2015 09:54:38 +0000 http://www.hindawi.com/journals/amse/2015/973648/ The magnetic Ni nanoparticles of 10–30 nm in size were synthesized by the reduction of Ni2+ by NaBH4 at room temperature. The amount of added water in the formation of Ni nanoparticles is a significant factor, which ensures that Ni nanoparticles are not oxidized by oxygen. XRD patterns and FESEM micrographs showed the constituent and structure and micromorphology. Congo red was used as adsorbate to quantitatively examine the adsorption capability of Ni nanoparticles for the organic dyes in industry wastewater. The magnetic hysteresis measurement indicated that the Ni nanoparticles presented ferromagnetic properties. The experimental results showed the as-obtained Ni nanoparticles might be a potential adsorbent in sewage treatment process. Genhua Zhang, Jianchen Li, Guangshu Zhang, and Lijun Zhao Copyright © 2015 Genhua Zhang et al. All rights reserved. An Analytical Gate-All-Around MOSFET Model for Circuit Simulation Wed, 12 Aug 2015 07:34:45 +0000 http://www.hindawi.com/journals/amse/2015/320320/ A generic charge-based compact model for undoped (lightly doped) quadruple-gate (QG) and cylindrical-gate MOSFETs using Verilog-A is developed. This model is based on the exact solution of Poisson’s equation with scale length. The fundamental DC and charging currents of QG MOSFETs are physically and analytically calculated. In addition, as the Verilog-A modeling is portable for different circuit simulators, the modeling scheme provides a useful tool for circuit designers. Kuan-Chou Lin, Wei-Wen Ding, and Meng-Hsueh Chiang Copyright © 2015 Kuan-Chou Lin et al. All rights reserved. Durability and Shrinkage Characteristics of Self-Compacting Concretes Containing Recycled Coarse and/or Fine Aggregates Wed, 12 Aug 2015 07:01:49 +0000 http://www.hindawi.com/journals/amse/2015/278296/ This paper addresses durability and shrinkage performance of the self-compacting concretes (SCCs) in which natural coarse aggregate (NCA) and/or natural fine aggregate (NFA) were replaced by recycled coarse aggregate (RCA) and/or recycled fine aggregate (RFA), respectively. A total of 16 SCCs were produced and classified into four series, each of which included four mixes designed with two water to binder (w/b) ratios of 0.3 and 0.43 and two silica fume replacement levels of 0 and 10%. Durability properties of SCCs were tested for rapid chloride penetration, water sorptivity, gas permeability, and water permeability at 56 days. Also, drying shrinkage accompanied by the water loss and restrained shrinkage of SCCs were monitored over 56 days of drying period. Test results revealed that incorporating recycled coarse and/or fine aggregates aggravated the durability properties of SCCs tested in this study. The drying shrinkage and restrained shrinkage cracking of recycled aggregate (RA) concretes had significantly poorer performance than natural aggregate (NA) concretes. The time of cracking greatly prolonged as the RAs were used along with the increase in water/binder ratio. Mehmet Gesoglu, Erhan Güneyisi, Hatice Öznur Öz, Mehmet Taner Yasemin, and Ihsan Taha Copyright © 2015 Mehmet Gesoglu et al. All rights reserved. Analysis of the Hybrid Power System for High-Altitude Unmanned Aircraft Tue, 11 Aug 2015 07:00:49 +0000 http://www.hindawi.com/journals/amse/2015/380708/ The application of single solar array on high-altitude unmanned aircraft will waste energy because of its low conversion efficiency. Furthermore, since its energy utilization is limited, the surface temperature of solar array will rise to 70°C due to the waste solar energy, thus reducing the electrical performance of the solar array. In order to reuse the energy converted into heat by solar array, a hybrid power system is presented in this paper. In the hybrid power system, a new electricity-generating method is adopted to spread the photovoltaic cell on the wing surface and arrange photothermal power in the wing box section. Because the temperature on the back of photovoltaic cell is high, it can be used as the high-temperature heat source. The lower wing surface can be a low-temperature cold source. A high-altitude unmanned aircraft was used to analyze the performances of pure solar-powered aircraft and hybrid powered aircraft. The analysis result showed that the hybrid system could reduce the area of wing by 19% and that high-altitude unmanned aircraft with a 35 m or less wingspan could raise the utilization rate of solar energy per unit area after adopting the hybrid power system. Kangwen Sun, Ming Zhu, Lifeng Wang, and Hu Liu Copyright © 2015 Kangwen Sun et al. All rights reserved. Obtaining Martensitic Structures during Thixoforming of Hypoeutectic Gray Cast Iron Mon, 10 Aug 2015 12:11:51 +0000 http://www.hindawi.com/journals/amse/2015/170562/ The control of parameters such as liquid fraction, holding time, and cooling rate during thixoforming can help control the final microstructure of the thixoformed part, thus improving its mechanical properties. This study intended to investigate conditions required to obtain martensite in hypoeutectic gray cast iron at 3.1% CE (carbon equivalent) deformed in the semisolid state. Samples heated up to 1130, 1135, and 1145°C (liquid fractions of 10, 30, and 45%) were compressed into platens without any holding time (0 s). If a sample presented a martensitic structure for 0 s holding time, new samples were retested at the same temperature for 30, 60, and 90 s holding times. The die casting process was simulated by allowing the platens to become locked after hot compression. Samples that cooled in the locked platens were submitted to higher cooling rates than samples that cooled with the platens open and presented martensite instead of the conventional ferrite and pearlite. Thus, the factor that had the greatest influence on the formation of martensite was the cooling rate rather than stress. The thixoforming process presented good morphological stability, which is highly desirable for industrial applications. Lucas Bertolino Ragazzo, Davi Munhoz Benati, Rodolfo Lopez Nadal, and Eugênio José Zoqui Copyright © 2015 Lucas Bertolino Ragazzo et al. All rights reserved. Genipin Cross-Linked Chitosan-Polyvinylpyrrolidone Hydrogels: Influence of Composition and Postsynthesis Treatment on pH Responsive Behaviour Thu, 06 Aug 2015 12:38:28 +0000 http://www.hindawi.com/journals/amse/2015/621289/ Understanding the factors that influence the pH responsive behaviour of biocompatible cross-linked hydrogel networks is essential when aiming to synthesise a mechanically stable and yet stimuli responsive material suitable for various applications including drug delivery and tissue engineering. In this study the behaviour of intelligent chitosan-polyvinylpyrrolidone-genipin cross-linked hydrogels is examined as a function of their composition and postsynthesis treatment. Hydrogels are synthesised with varying amounts of each component (chitosan, polyvinylpyrrolidone, and genipin) and their response in a pH 2 buffer is measured optically. The influence of postsynthesis treatment on stability and smart characteristics is assessed using selected hydrogel samples synthesised at 30, 40, and 50°C. After synthesis, samples are exposed to either continuous freezing or three freeze-thaw cycles resulting in increased mechanical stability for all samples. Further morphological and mechanical characterisations have aided the understanding of how postsynthesis continual freezing or freeze-thaw manipulation affects network attributes. Chinyelumndu Jennifer Nwosu, Glenn Adam Hurst, and Katarina Novakovic Copyright © 2015 Chinyelumndu Jennifer Nwosu et al. All rights reserved. Modeling and Analysis of Mechanical Properties of Aluminium Alloy (A413) Processed through Squeeze Casting Route Using Artificial Neural Network Model and Statistical Technique Wed, 05 Aug 2015 13:47:38 +0000 http://www.hindawi.com/journals/amse/2015/714762/ Artificial Neural Network (ANN) approach was used for predicting and analyzing the mechanical properties of A413 aluminum alloy produced by squeeze casting route. The experiments are carried out with different controlled input variables such as squeeze pressure, die preheating temperature, and melt temperature as per Full Factorial Design (FFD). The accounted absolute process variables produce a casting with pore-free and ideal fine grain dendritic structure resulting in good mechanical properties such as hardness, ultimate tensile strength, and yield strength. As a primary objective, a feed forward back propagation ANN model has been developed with different architectures for ensuring the definiteness of the values. The developed model along with its predicted data was in good agreement with the experimental data, inferring the valuable performance of the optimal model. From the work it was ascertained that, for castings produced by squeeze casting route, the ANN is an alternative method for predicting the mechanical properties and appropriate results can be estimated rather than measured, thereby reducing the testing time and cost. As a secondary objective, quantitative and statistical analysis was performed in order to evaluate the effect of process parameters on the mechanical properties of the castings. R. Soundararajan, A. Ramesh, S. Sivasankaran, and A. Sathishkumar Copyright © 2015 R. Soundararajan et al. All rights reserved. Effect of the Change of Deposition Time on the Secondary Direction and Abnormal Shape of Grains Growth of SnO2 Thin Films Tue, 04 Aug 2015 13:43:22 +0000 http://www.hindawi.com/journals/amse/2015/350196/ SnO2 thin films were grown on Si substrate using the low pressure chemical vapor deposition method. Observations made through electron microscopy indicate that thin films tend to grow with a constant direction when deposited at a temperature of 420°C for 5, 10, 20, or 30 min. However, when the deposition time increases, the particles forming the thin films are subject to a secondary growth. Observations made under a high-resolution transmission electron microscope reveal the lattice shape characteristic of thin films, with an overlapped or wrinkled flower form, and indicate that thin films growth takes place in different directions during the secondary growth. Measurements of the Hall effect show that the carriers mobility in the thin films increases linearly with the deposition time, whereas the carrier density decreases. The Hall Rh value increased linearly until 20 min deposition time, whereas for thin film grown for 30 min it decreased rapidly, showing a relatively similar behaviour to the carrier density. This is because as the deposition time becomes longer, the second growth and atypical shape occurs, leading to an increase of the thin films Rh value. This phenomenon indicates that the deposition time of thin films affects their carrier density and atypical overlapped or wrinkled flower form. Jin Jeong Copyright © 2015 Jin Jeong. All rights reserved. Trend and Development of Semisolid Metal Joining Processing Tue, 04 Aug 2015 12:00:47 +0000 http://www.hindawi.com/journals/amse/2015/846138/ The semisolid metal joining (SSMJ) process or thixojoining process has recently been developed based on the principles of SSM processing, which is a technology that involves the formation of metal alloys between solidus and liquidus temperatures. Thixojoining has many potential benefits, which has encouraged researchers to carry out feasibility studies on various materials that could be utilized in this process and which could transform the production of metal components. This paper reviews the findings in the literature to date in this evolving field, specifically, the experimental details, technology considerations for industrialization, and advantages and disadvantages of the various types of SSMJ methods that have been proposed. It also presents details of the range of materials that have been joined by using the SSMJ process. Furthermore, it highlights the huge potential of this process and future directions for further research. M. N. Mohammed, M. Z. Omar, Z. Sajuri, M. S. Salleh, and K. S. Alhawari Copyright © 2015 M. N. Mohammed et al. All rights reserved. Numerical Study on Crack Propagation by Using Softening Model under Blasting Sun, 02 Aug 2015 16:05:24 +0000 http://www.hindawi.com/journals/amse/2015/108580/ A mixed failure criterion, which combined the modified maximum principal stress criterion with the damage model of tensile crack softening, was developed to simulate crack propagation of rock under blasting loads. In order to validate the proposed model, a set of blasting models with a crack and a borehole with different incident angles with the crack were established. By using this model, the property of crack propagation was investigated. The linear equation of state (EOS) was used for rock, and the JWL EOS was applied to the explosive. In order to validate the numerical simulation results, experiments by using PMMA (polymethyl methacrylate) with a crack and a borehole were carried out. The charge structure and incident angle of the blasting experimental model were the same as those in the numerical models. The experiment results agree with the numerical simulation results. Rong Hu, Zheming Zhu, Jun Xie, and Dingjun Xiao Copyright © 2015 Rong Hu et al. All rights reserved. Effects of Nano-TiO2 on the Toughness and Durability of Cement-Based Material Thu, 30 Jul 2015 08:43:29 +0000 http://www.hindawi.com/journals/amse/2015/583106/ The effects of nano-TiO2 (NT) on microstructures and mechanical properties of cement mortars were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and mercury intrusion porosimetry (MIP). Results show that 3% NT can remarkably increase the tensile/flexural strengths (i.e., the toughness is improved) and promote the precipitation of AFt crystal. The flexural and tensile strengths have significant positive correlation to the formation amount of AFt. The pores of mortars can be significantly refined and shift to harmless pores by controlling the growth of CH crystal and increasing the hydration reaction rate. The durability of cement-based materials is discussed by testing their water absorption and water-vapour permeability. Results show that the addition of 3% NT can decrease the water absorption ratio by 40–65%, water absorption coefficients by more than 40%, and water-vapour permeability coefficients by 43.9%, indicating that 3% NT can effectively improve the compactness and durability of cement-based materials. Baoguo Ma, Hainan Li, Junpeng Mei, Xiangguo Li, and Fangjie Chen Copyright © 2015 Baoguo Ma et al. All rights reserved. Preparation, Characterization, and Photocatalytic Properties of Modified Red Mud Wed, 29 Jul 2015 08:38:22 +0000 http://www.hindawi.com/journals/amse/2015/907539/ Solid waste red mud was modified by HCl leaching. The structure property and composition of modified red mud were investigated by X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET). Under UV irradiation, methyl orange (MO) aqueous solution was photodegraded by modified red mud. The obtained results showed that the specific surface area of modified red mud was 317.14 m2/g, which was about 40 times higher than that of the normal red mud. After UV irradiation for 50 min, the removal percentage of MO reached 94.2%. The study provided a novel way for the application of red mud to the photocatalytic degradation of organic wastes. Mingjie Ma, Guanyu Wang, Zhengpeng Yang, Shanxiu Huang, Weijie Guo, and Yuxia Shen Copyright © 2015 Mingjie Ma et al. All rights reserved. Application of Biomaterials and Inkjet Printing to Develop Bacterial Culture System Tue, 28 Jul 2015 11:45:40 +0000 http://www.hindawi.com/journals/amse/2015/290790/ We created an automated bioassay system based on inkjet printing. Compared to conventional manual bacterial culture systems our printing approach improves the quality as well as the processing speed. A hydrophobic/hydrophilic pattern as a container supporting a culture medium was built on filter paper using a toluene solution of polystyrene for hydrophobization, followed by toluene printing to create several hydrophilic areas. As culture media we used a novel poly(vinyl alcohol) based hydrogel and a standard calcium alginate hydrogel. The poly(vinyl alcohol) hydrogel was formed by physical crosslinking poly(vinyl alcohol) with adipic acid dihydrazide solutions. The conditions of poly(vinyl alcohol) gelation were optimized for inkjet printability and the optimum mixture ratio was determined. The calcium alginate hydrogel was formed by chemical reaction between sodium alginate and CaCl2 solutions. Together with nutrients both hydrogel solutions were successfully printed on paper by means of the modified inkjet printer. The amount of each solution was demanded simply by outputting CMYK values. In the last step bacterial cells were printed on both hydrogel media. For both media we achieved a stable bacteria growth which was confirmed by microscopical imaging of the developed bacterial colonies. Tithimanan Srimongkon, Shusaku Mandai, and Toshiharu Enomae Copyright © 2015 Tithimanan Srimongkon et al. All rights reserved. Physical and Thermal Characterization of Alkali Treated Rice Husk Reinforced Polypropylene Composites Mon, 27 Jul 2015 13:27:17 +0000 http://www.hindawi.com/journals/amse/2015/907327/ Rice husk (RH) reinforced polypropylene- (PP-) based composites were prepared by compression molding. The RH was treated with sodium hydroxide solution (1 wt%); then composites were prepared using varying percentages of RH (5 to 20 wt%). The thermomechanical, spectroscopic, and morphological properties of the prepared composites (RH-PP) were investigated. The scanning electron microscopic (SEM) analysis showed better interfacial adhesion between alkali treated RH and the matrix PP. The Fourier Transform Infrared (FTIR) spectra confirmed the chemical bonding.The results revealed that physical properties as well as thermal stability of the composites improved significantly with the addition of alkali treated RH in PP matrix. Ismat Zerin Luna, Krishna Chandra Dam, A. M. Sarwaruddin Chowdhury, Md. Abdul Gafur, Nuruzzaman Khan, and Ruhul A. Khan Copyright © 2015 Ismat Zerin Luna et al. All rights reserved. Asphalt Mixture for the First Asphalt Concrete Directly Fastened Track in Korea Mon, 27 Jul 2015 09:02:03 +0000 http://www.hindawi.com/journals/amse/2015/701940/ The research has been initiated to develop the asphalt mixtures which are suitable for the surface of asphalt concrete directly fastened track (ADFT) system and evaluate the performance of the asphalt mixture. Three aggregate gradations which are upper (finer), medium, and below (coarser). The nominal maximum aggregate size of asphalt mixture was 10 mm. Asphalt mixture design was conducted at 3 percent air voids using Marshall mix design method. To make impermeable asphalt mixture surface, the laboratory permeability test was conducted for asphalt mixtures of three different aggregate gradations using asphalt mixture permeability tester. Moisture susceptibility test was conducted based on AASHTO T 283. The stripping percentage of asphalt mixtures was measured using a digital camera and analyzed based on image analysis techniques. Based on the limited research results, the finer aggregate gradation is the most suitable for asphalt mixture for ADFT system with the high TSR value and the low stripping percentage and permeable coefficient. Flow number and beam fatigue tests for finer aggregate asphalt mixture were conducted to characterize the performance of asphalt mixtures containing two modified asphalt binders: STE-10 which is styrene-butadiene-styrene (SBS) polymer and ARMA which is Crum rubber modified asphalt. The performance tests indicate that the STE-10 shows the higher rutting life and fatigue life. Seong-Hyeok Lee, Dae-Wook Park, Hai Viet Vo, and Samer Dessouky Copyright © 2015 Seong-Hyeok Lee et al. All rights reserved.