bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling and Influence of Machining Parameters on Titanium Aloy
Authors: Saedon J.B. , Jaafar Norkamal , Jaafar Roseleena , Saad Nor Hayati , Kasim Mohd Shahir
Published: March 2014

Wire electrical discharge machining (WEDM) is a material removal process of electrically conductive materials by the thermo-electric source of energy which is extensively used in machining of materials for a highly precision productivity. This work presents the machining of titanium alloy (TI-6AL-4V) using WEDM with a brass wire diameter of 0.25mm.The objective of this work is to study the influence of three machining parameters, namely peak current (IP), feed rate (FC) and wire tension (WT) to cutting speed and surface roughness as a responses. Response Surface Methodology was used to develop second order model in order to predict cutting speed and surface roughness responses. The results showed that the average percentage error between the predicted and experimental value for both models was less than 2%. Effects of each parameter and their interaction with percentage contribution ratios (PCR) are included for each response.
Evaluation of Thermal Gelation of F-127 in a Non-Aqueous Solvent and its Suitability as a Support Material for Additive Manufacturing
Authors: Fahad Muhammad , Khan Maqsood Ahmed , Gilbert Marianne
Published: March 2014

Pluronics are well known for their reverse thermal gel (RTG) formation in aqueous solutions and have been used in a variety of industrial applications. Additive Manufacturing processes that utilize jetting technology require support materials for building parts that comprise holes, cavities and/or overhangs. Currently available support materials include waxes which due to their brittleness, are weak and can lead to accuracy issues during part building via jetting technology. Pluronic F-127 in a non-aqueous solvent (Formamide) have been investigated in this paper for thermal gelation at elevated temperatures and the suitability of this composition as support material for jetting based AM processes have been evaluated.
Thermal Performance on Unglazed Photovoltaic Thermal Polymer Collector
Authors: Rosli Mohamad Afzanizam Bin Mohd , Mat Sohif , Sopian Kamaruzzaman , Sulaiman Mohd Yusof , Salleh Elias Ilias , Sharif Mohd Khairul Anuar
Published: March 2014

In this study, the thermal efficiency of a polymer collector with unglazed photovoltaic thermal (PVT) system was determined. Overall heat loss was estimated using the heat energy balance method. Based on the analysis, the heat removal factor of the PVT system was found to be 0.55. The thermal performance of the system was 47% during the zero reduce temperature. The unglazed PVT polymer collector could replace the conventional PVT collector, which encountered problems such as high cost, weighting issues, and corrosion.
The Effects of Temperature on Rheology Properties and Filtrate after Using Lemongrass as Lost Circulation Materials for Oil Based Drilling Mud
Authors: Ghazali N.A. , Mohd T.A.T. , Alias N. , Shahruddin M.Z. , Sauki Arina , Maliki M.B.F.
Published: March 2014

Lost circulation materials (LCM) are used to combat mud loss to the reservoir formation which can cause problems during drilling operation. Difficulties in handling and costly are those challenges faced by drilling operator. Mostly LCM can work better in water based mud compared to oil based mud due to characteristic of LCM itself. Nowadays, most of operator interested in the ultra-deep water due to the limitation of reservesand deals with high temperature and high pressure conditions.Oil based mud (OBM) is more preferable in high temperature conditions compared to water based mud hence a laboratory study was carried out to investigate the effect of temperature on the performance of lemongrass with different sizes in oil based mud. The oil based mud was formulated and tested with three different temperatures which are 250oF, 275oF and 350oF. The lemongrass LCM was prepared with three different sizes which are 150 microns, 250 microns and 500 microns. The sizes distribution of LCM is one of the main contributors to the success of LCM in the formation. The oil based mud samples were tested using Fann Viscometer to determine rheology properties and HPHT Filter Press to investigate the amount of filtrate. It was found that different temperatures and sizes have great effects on the lemongrass LCM in the oil based mud. The optimum temperature for lemongrass LCM is 275oF and with the sizes of 250 microns.
Platinum-Incorporating Graphene Counter Electrode for In2O3-Based DSSC with Various Annealing Temperatures
Authors: Abdullah Huda , Mahalingam Savisha , Omar Azimah , Razali Mohd Zikri , Shaari Sahbudin , Asshaari Izamarlina
Published: March 2014

Development of platinum incorporating graphene (pt/graphene) thin films was prepared by sol-gel method via chemical bath deposition (CBD). Indium oxide (In2O3) as photoanode and pt/graphene as counter electrode is used to analyse the characteristics and performance of dye-sensitized solar cell (DSSC). Different annealing temperatures of 200 oC, 250 oC and 300 oC were proposed for the counter electrode in this study. The changes in the structural properties were analyzed by means of X-ray Diffraction (XRD) and atomic force microscopy (AFM) analysis. AFM results indicated very rough surface area of graphene sheet where roughness values decreased linearly from 0.65 μm to 0.18 μm by an increment in annealing temperature. The In2O3-based DSSC exhibited good photovoltaic performance with power conversion efficiency (η), photocurrent density (Jsc), open circuit voltage (Voc) and fill factor (FF) of 0.47 %, 5.46 mA cm-2, 0.54 V and 0.36 respectively. The obtained structural and photovoltaic performance analysis was proposed as a suitable benchmark for pt/graphene counter electrode with In2O3-based DSSC.
Characterization and Composition of Oil Extracted from Bastard Poom Beans (Sterculia foetida L) and its Potential as a Biofuel
Authors: Sinthorn C. , Sakkampang C. , Wongwuttanasatian T.
Published: March 2014

The paper describes an investigation of using oil extracted from Bastard Poom beans as a biofuel. Unlike Palm oil, Bastard Poom bean oil is non-edible, therefore using it as a fuel does not create a demand conflict between food and fuel. Bastard Poom are a type of softwood trees and grown quickly. We find that to obtain a liter of oil, approximately 4.29 kg of beans are needed (oil extraction ratio of 21.57 % by weight). The chemical compositions of oil are determined. The oil consists of 40.16 %. Palmitic acid, 15.67 % Cis-11,14-Eicosadienoic acid and approximately 15 % each of Cis-9-Oleic and Cis-9,12-Linoleic acids. The oil heating value is 39,638 kJ/kg. The viscosity tested at 40 °C and densities tested at 15 °C are 44.61 mm2/s and 929.6 kg/m3, respectively. As a result, it has a considerable potential as an alternative to other biofuels among communities and farmers.
Adsorption Capacity of Nickel (II) and Cobalt (II) Ions from Aqueous Solutions by Oil Palm Waste and Sawdust
Authors: Fuadi Farah Aimi , Nor-Azemi Siti Nor Izuera , Syed-Hassan Syed Shatir A.
Published: March 2014

Four types of biomass were characterized to investigate its metal adsorption capacity. The biomass were soaked in with nickel and cobalt solutions to examine the effect of biomass to amount of metal adsorbed. Oil palm mesocarp fibre (OPMF), empty fruit bunch (EFB), palm kernel shell (PKS) and sawdust were used in this study. Among all the biomass studied, oil palm mesocarp fibre shows the highest adsorption capacity with 1.8 mg/g and 1.6 mg/g of nickel and cobalt uptake, respectively. The metals adsorbed on the biomass were found to disperse into nanosize range.
Electrokinetics-Based Microfluidic Technology for the Rapid Separation and Concentration of Bacteria/Cells/Biomolecules
Authors: Cheng I Fang , Chen Tzu Ying , Chang Hsien Chang
Published: March 2014

Conventional techniques for detection of bacteria/cell and assessment of cancer cell typically use DNA techniques, Western blot and ELISA kits that are high cost, complicated processes and long time consuming. Our researches focus on rapid, portable, simple and highly sensitive separation and detection of cells/bacteria/biomolecules for field-use diagnosis. An ideal portable biosensor (molecular or whole cells detections) unit must have several important features: rapid detection time (<10 minutes), high sensitivity (pM level for molecular detection, 103 cells/ml for whole cell detection), high specificity, small and inexpensive instrumentation configuration. Electrochemical impedance/conductance sensing is preferred over optical detection because of cost and portability concerns. Cancer cell detection using heterogeneous medical samples require continuous isolation, sorting, and trapping of the target bioparticles and immunocolloids within a diagnostic chip. We have developed several electrokinetic strategies to rapid separation, concentration and detection of cells/bacteria/biomolecules in a microfluidic chip using such as dielectrophoresis (DEP), traveling-wave dielectrophoresis (twDEP) and electrohydrodynamics (EHD). Several key techniques we done, which on a rapid/simple/label-free detection platform for the highly sensitive on-chip separation/identification/quantification will be introduced in this paper.
Rheological Properties of Hydroxyapatite Synthesized Clamshell Mix with Palm Stearin Binder System
Authors: Subuki Istikamah , Nurul Huda Ali , Ismail Muhammad Hussain
Published: March 2014

This study investigated the flow behavior of feedstock containing hydroxyapatite (HAp) powder with palm stearin (PS) based binder system. The HAp was synthesized via chemical precipitation method with the use of waste of clamshells. The result showed that single phase synthesized HAp was successfully formed at annealing temperature and pH solution of 850°C and 6.5, respectively. The synthesized HAp with a volume fraction of 65% was then mixed with PS and and Polyethylene binder at 160°C to prepare a feedstock. From the rheological test result, it was found that the feedstock exhibited a pseudoplastic behavior with low values of shear sensitivity in comparison with commercial HAp.
Ignition by Thermal Radiation of Polyethylene and Human Feces Combustible Wastes: Time and Temperature to Ignition
Authors: Monhol Filipe Arthur Firmino , Martins Marcio Ferreira
Published: March 2014

Due to the growing energy demands of the world and the rapid depletion of fossil fuels, it is necessary to study new energy sources. The waste have a great potential to be tapped, as besides being a raw material abundant, their use helps in reducing the level of environmental pollution and curbing the volume of waste in cities. However, one should know well the combustion process these waste before using them as fuel. Thus, Ignition behavior of combustible wastes was studied in a built fixed bed reactor. To provide a controlled thermal radiation for the ignition instant, a radiative heat flux is generated by a metal surface called a cone heater calibrated to establish the radiative heat flux density provided by a thermal resistance of 2 kW. The heat flux was 25 to 30 kWm2 over the top surface of the fuels. To validate the process, experiments with charcoal were performed varying the diameter of particles and air flow. After this, the polyethylene and human feces were analyzed. Their effects were investigated on the ignition time.
Influence of Blast Furnace Slag Content on High Performance Concrete Behavior
Authors: Talah Aissa , Kharchi F.
Published: March 2014

This paper reports an experimental study of influence of finely ground-granulated blast-furnace slag (GGBS) used as partial replacement of Portland cement (PC) on the mechanical properties and durability of high performance concretes. The analysis of the experimental results on concrete at 17.5% content of blast furnace slag with a fineness modulus of 8500 cm2/g, in a chloride environment, showed that it contributes positively to the perfection of its mechanical characteristics, its durability with respect to water absorption and migration of chloride ions. On the basis of the experiments performed, it can be concluded that the GGBS is suitable for formulation of high performance concretes (HPC) and their properties are significantly better compared to the reference concrete (RC).
Investigations of Rubber Dipping by-Product on Bitumen Properties
Authors: Hainin Mohd Rosli , Warid Muhammad Naqiuddin Mohd , Izzul R. , Ruzaini M.K. , Mohd Ibrahim Mohd Yusak
Published: March 2014

Nowadays, there are a lot of damaged of road pavement and it become a very serious issue in Malaysia. To minimise the damage of pavement surface and increase durability of flexible pavement, the conventional bitumen needs to be improved with regards to performance related properties. Thus, this study is to investigate the effect of rubber dipping by-product (RDP) on bitumen properties. In order to achieve this aim, the objectives of this study are; i) to determine of non-modified bitumen and the effect of added RDP in different concentration on bitumen properties; and ii) to compare non-modified bitumen and RDP modified bitumen in terms of physical properties. RDP is waste material from natural rubber industrial and it is in solid forms. Bitumen grade 80/100 PEN was used in this study. Laboratory tests were penetration, softening point, viscosity, rolling thin film oven (RTFO) and pressure aging vessel (PAV) tests. The findings show that addition of RDP causes the modified bitumen harder than before, indicate higher temperature susceptibility and increased viscosity properties. From the study stated that the suggested proportion of RDP to be mixed with bitumen is 10 percent by total weight.
Characterization of Nafion/Silica Hybrid Composite Membranes for Redox Flow Battery (RFB) Applications
Authors: Haryadi Haryadi , Gunawan Y.B. , Mursid S.P. , Haryogi D.
Published: March 2014

Nafion/Silica hybrid membranes were prepared via in situ solgel method for redox flow battery (RFB) system. In this work, a novel Nafion/organically modified silicate hybrids nanocomposite membrane was prepared via in situ solgel reactions for mixtures of tetraethoxysilane (TEOS) and trimethoxyprohanthiol (TMSP). The primary properties of Nafion/Silica hybrids membrane were measured and compared with Nafion and Nafion/SiO2 hybrid membranes. Fourier transform infrared spectra (FT-IR) analysis of the hybrids membranes reveal that the silica and organic modified silica phase is well formed within hybrids membrane. The XRD results indicate thatthe Nafionhybrid membranes are not influenced by SiO2 nanoparticles.Nafion/Silica hybrid membrane shows nearly the same ion exchange capacity (IEC) and slightly greater of proton conductivity as pristine Nafion-117 membrane. The water uptake for Nafion/Organosilica hybrids membrane shows greatly reduced than a pristine Nafion 117, suggesting of low water cross over that is mostly faced in the RFB applications.
Compressive and Flexural Strength of Foamed Concrete Containing Polyolefin Fibers
Authors: Wan Ibrahim Mohd Haziman , Jamaluddin Norwati , Irwan J.M. , Ramadhansyah P.J. , Suraya Hani A.
Published: March 2014

Foam concrete is a lightweight concrete which is produced relatively inexpensively. However, due to its low strength and brittleness the application in building construction is rather limited. A study has been undertaken to investigate the effects of polyolefin fibers at a relatively low volume fraction (0 %, 0.2 %, 0.4 % and 0.6 %) on the compressive and flexural properties of foamed concrete. The foamed concrete was designed to achieve a target strength of 8-10 MPa with a density of 1600 kg/m3 at the age of 28 days. For each mixture, nine 100x100x100 mm cubes and three 100x100x500 mm beam were prepared. The compressive test was performed on cubes and three points loading flexural test on the beams was carried out in accordance to MS 26:Part 2:1991. Test results showed that polyolefin fibers only slightly improved the compressive strength and flexural strength of foamed concrete by 4.3% and 9.3% respectively.
Corrosion of the Pozzolan Concrete in Sulfates
Authors: Merida Ahcene , Kharchi Fattoum
Published: March 2014

Sulfate attack and its effects are important from both scientific and industrial viewpoints. Itis perceived that cements containing pozzolan have better performance in sulfate solutions,since the pozzolanic reactions reduce the quantity of calcium hydroxide and increasecalcium silicate hydrate. This paper investigates the physical and mechanical properties ofconcretes made by blended cement containing Algerian natural pozzolan of volcanic origin, and Portland cement. in order to better determine the pozzolanic effect of the pozzolan addition in the concrete, the analysis of the experimental results of the effect of the partial replacement of the cement by the naturalpozzolana showed that it contributes positively to the improvement of its mechanical characteristics, its durability with respect to the permeability to the chlorine ions, the ultrasonic pulse velocity as well as the sulphate resistance. The present study confirms the pozzolanic reactivity of the natural pozzolans used.
An Empirical Study on Time Lag Phenomenon Regarding Summertime Indoor Thermal Environments in the Domestic Buildings of Different Construction Types in Hot-Humid Climate Zone
Authors: Hsieh Hung Ren , Chen Wun Yuan , Yu Hsin
Published: March 2014

In the empirical case studies of the seven detached house buildings situated in Yilan, Taiwan in a hot and humid climate, this research conducted the actual measurements and analysis of the Summertime Indoor and Outdoor thermal environment parameters in order to accomplish the research of Time Lag Phenomenon of Summertime Indoor Temperature and Humidity in the Buildings of Light (Composite) Constructions and Heavy (Reinforced Concrete) Constructions. Firstly, it indicated that given the condition of doors and windows in closed positions, there would be Time Lag Phenomenon for both of the indoor Temperature and Humidity measurements in domestic buildings. The Temperature Time Lag for Heavy Construction Buildings had a duration of around three hours, almost as twice that of the figure for Light Construction Buildings. There was a significant correlation between Quantity of Interior Finishes and Humidity Time Lag inside domestic buildings, whereas the bigger the Quantity of Interior Finishes, the longer the Humidity Time Lag. Secondly, it also showed that given the condition of doors and windows in opened positions, there was almost zero Time Lag for both of the domestic indoor Temperature and Humidity measurements. Last but not least, generally speaking, the Ratio of Indoor/Outdoor Diurnal Temperature Range of Light Construction Buildings were higher than that of Heavy Construction Buildings. In particular, given the condition of doors and windows in opened positions with natural ventilation in summertime, it was slightly cooler inside the Light Construction Domestic Buildings than the Heavy Construction Domestic Buildings.
Calculating of the Relative Preference of Criteria Affecting Electroless Coating of Alumina Nano Particles on Ni-B by Analytic Hierarchy Process (AHP) Method
Authors: Towhidi Nasser , Allahkaram Saeed Reza , Hekmat Amir , Alivand Reza Faezi
Published: March 2014

In metallurgical engineering, there are different criteria affected on coating on surface of the material such as physical, chemical, mechanical, electrical and economical properties. In this study, using the Analytic Hierarchy Process (AHP) to calculation the performance of criteria for priority by addition of different concentration alumina (Al2O3)nanoparticles in Electrolyte and heat treatment on substrate nickel-borne electroless method has been calculated. The alumina particles with an average grain size of 50nm in different concentrations were added to a solution electroless Ni-B plating which were coated on conventional steel sample. The AHP determined that the most favorable concentration of alumina particles is 1gr/lit .
Laser Cladding of Wear Resistant Stellite 6 Coating on P22 Steel Substrate with Two Different Energy Inputs
Authors: Kusmoko Alain , Dunne Druce , Li Hui Jun , Nolan David
Published: March 2014

Stellite 6 was deposited by laser cladding on a P22 steel substrate with energy inputs of 1 kW (P22-1) and 1.8 kW (P22-1.8). The chemical compositions and microstructures of these coatings were characterized by atomic absorption spectroscopy, optical microscopy and scanning electron microscopy. The microhardness of the coatings was measured and the wear mechanism of the coatings was examined using a pin-on-plate (reciprocating) wear testing machine. The results showed less cracking and pore development for Stellite 6 coatings applied to the P22 steel substrate with the lower heat input (P22-1). Further, the Stellite coating for P22-1 was significantly harder than that obtained for P22-1.8. The wear test results showed that the weight loss for P22-1 was much lower than for P22-1.8. It is concluded that the lower hardness of the coating for P22-1.8, markedly reduced the wear resistance of the Stellite 6 coating.
Grasshopper Knee Joint – Inverse Kinematic Modeling and Simulation of Ionic Polymer Metal Composites (IPMC) Actuators
Authors: Farid Muhammad , Gang Zhao , Khuong Tran Linh , Sun Zhuang Zhi , Ur Rehman Naveed
Published: March 2014

Biomimetic is the field of engineering in which biological structures and functions are analyzed and are used as the basis for the design and manufacturing of machines. Insects are the most populated creature and present everywhere in the world and can survive the most hostile environmental situations. IPMC is a smart material which has exhibited a significant bending and tip force after the application of a low voltage. It is light-weighted, flexible, easily actuated, multi-directional applicable and requires simple manufacturing.In this paper,five different contributions are made. Firstly, a two link grasshopper knee joint physical model is presented in which the actuation force required for moving the knee is provided by the IPMC material. This material constitutes one link of the linkage. Secondly,inverse kinematic modelhas been developed for the linkage. Thirdly, the system of equations is solved by proposing solutions to the known transcendental functions with unknown coefficients. Fourthly, wolfram mathematica is employed for thesimulationof the model. Finally,angles, velocity and accelerationof the links are analyzed based on the simulation results. The simulation results show that the tibia is displaying a lag in time from the femur verifying that it is operated by the force provided by the femur (IPMC). Also, it verified the flexible nature of the IPMC material through multiple peaks and troughs in the graphs. The angles range of the tibia is found quite admirable and it is believed that the IPMC material can add a new horizon to the manufacturing of small biomimetic equipment and low force actuated manipulators.
Grasshopper Knee Joint - Torque Analysis of Actuators Using Ionic Polymer Metal Composites (IPMC)
Authors: Farid Muhammad , Gang Zhao , Khuong Tran Linh , Sun Zhuang Zhi
Published: March 2014

Biomimetic is the field of engineering which involves analyzing the biological beings and incorporating their designs and systems for manufacturing mechanical systems. An Ionic Polymer metal composite (IPMC) is a smart material that displays a significant bending and tip force after the application of a low voltage. It is light-weighted, flexible, easily actuated, multi-directional applicable and requires simple manufacturing. In this paper, a two-link biomimetic knee joint mechanism of a grass hopper is presented. Secondly, an IPMC pair of strips is proposed as a link that enables the actuating force which is modeled on the basis of the grass hopper's leg. Thirdly, dynamic model is developed for the proposed mechanism through Lagrangian mechanics. Fourthly, power series is utilized for the solution of the non-linear transcendental model. Wolfram mathematica is employed for the simulation of the model. Finally, the effect of torque is analyzed by varying the actuating torque. It is concluded that actuating torque is directly proportional to the angles moved and inversely proportional to the potential energies of the linkage. Furthermore, a stiffer and more vibrant linkage is observed as per simulation results. These results are validated theoretically. Our simulation results indicate that the proposed IPMC has the potential for utilization in small biomimetic applications like insects robots joints activation, underwater fish fins, surgical grippers, synthetic ventricular muscles and human catheter system for endoscopic surgery and diagnostics etc.
Effect of Unilateral Non-Rhythmical Stimulation on Bilateral Cerebral Cortex and Muscle Activation in People
Authors: Sui Jian Feng , Liu Ya Li , Ji Lin Hong
Published: March 2014

Effects of conventional exercise training of robot to stroke patients are not too satisfying, and efficient methods of training are unclear. To test how the non-rhythmical load stimulation affects cerebral cortex by analyzing the coherence between electroencephalographic signals (EEGs) and electromyographic signals (EMGs). Ten healthy subjects, all subjects have no history of neurological diseases (6 men and 4 women, mean age: 24.5 years, range: 22-28). Subjects lay on the experimental platform 75°with respect to the ground, feet on support plates and close to the ground. When non-rhythmical stimulation was performed randomly, one hinge was released and the respected braced force between the foot and support plate disappeared, which caused the corresponding ankle to extend suddenly without relative displacement between the foot and the support plate. Surface EMG signals from tibialis anterior (TA) muscles and EEG signals from cerebral cortex area Cz were recorded, and coherence between them were analyzed. The mean maximum EEG-EMG coherence of the non-rhythmical stimulation side of the ten subjects was consistent across all (9 of 10) within β range (13-30 Hz), and the average value of all in the stimulated side was 23.581Hz. While the mean maximum EEG-EMG coherence of the still side were consistent across all (9 of 10) within α range (8-13 Hz). Our findings suggest that non-rhythmical stimulation to lower limb can stimulate effectively the corresponding area of the cerebral cortex, and this idea could be applied in rehabilitation of central nervous system diseases like stroke.
Advances on Biomedical Titanium Surface Interactions
Authors: Bousnaki Maria , Koidis Petros
Published: March 2014

When used as an implanted material, titanium (Ti) surface controls the subsequent biological reactions and leads to tissue integration. Cells interactions with the surface, through a protein layer that is being formed from the moment Ti surface comes in contact with blood and its components, and indeed this protein layer formation, are regulated by surface properties such as topography, chemistry, charge and surface energy. Currently, the implementation of nanotechnology, in an attempt to support mimicking the natural features of extracellular matrix, has provided novel approaches for understanding and translating surface mechanisms whose modification and tailoring are expected to lead to enhanced cell activity and improved integration. Despite the fact that there has been extensive research on this subject, the sequence of interactions that take place instantly after the exposure of the implanted material into the biologic microenvironment are not well documented and need further investigation as well as the optimization of characteristics of Ti surface. This review, including theoretical and experimental studies, summarizes some of the latest advances on the Ti surface concerning modifications on surface properties and how these modifications affect biomolecular reactions and also attempts to present the initial adsorption mechanism of water and protein molecules to the surface.
Effects of Cell Density on Mechanical Properties of Alginate Hydrogel Tissue Scaffolds
Authors: Tian Xiao Yu , Chen Xiong Biao
Published: March 2014

Cell-seeded hydrogel scaffolds have been widely used in various tissue engineering applications due to their excellent biocompatibility and biomimetic properties. One of the critical issues in successful use of hydrogel scaffolds is their mechanical properties. Since cells and hydrogels are physically different materials, the cells encapsulated in the hydrogels can change profoundly the mechanical properties of the hydrogel scaffolds. In this research, the effects of Schwann cell density on mechanical properties of alginate hydrogel scaffolds were investigated. It was found that increase of cell density decreases the strength of the scaffolds. It was also found that the Ogden model can best describe the mechanical properties of the scaffolds under the strain of 45% at varying cell densities. Based on the cell density-dependant mechanical properties, a simulation was performed to study the local stresses of on cells when cells are subjected to loading. Simulation shows that at the same strain, the stress concentration on cells decreases as the cell density increases. The experimental and simulation results obtained in this paper will allow one to rigorously design scaffolds with desired mechanical properties and provide a clue to avoid mechanical cell injury.
Damping Micromechanisms for Bones above Room Temperature
Authors: Lambri Osvaldo A. , Pérez-Landazábal José Ignacio , Bonifacich Federico G. , Recarte Vicente , Lambri Melania L. , Zelada Griselda I. , Tarditti Federico , Gargicevich Damián
Published: March 2014

The wide damping maximum which is reported to appear in bones, involving both cortical and cancellous parts, between around 280 K and 420 K; has been determined to be a composition of different processes taking place at different temperatures in cancellous and cortical parts. In fact, in the present work the mechanical response of cow ribs bones has been analysed by coupling mechanical spectroscopy, differential scanning calorimetry, thermogravimetry and scanning electron microscopy studies. Cancellous part develops two damping maxima at around 320 K and 350 K. Cortical part exhibits a wide maximum in damping between around 310 K and 410 K and another damping relaxation between 390 K and 410 K. The physical-chemical driving force giving rise to the above relaxation processes are discussed.
Effects of Annealing Ambient on Electrical Properties of LaBaCo2O5+δ Thin Films
Authors: Liu Ming , Ma Chun Rui , Enriquez Eric , Xu Xing , Bao Shan Yong , Chen Chong Lin
Published: March 2014

Highly epitaxial LaBaCo2O5+δthin films are successfully fabricated and annealed in different ambient conditions. The LaBaCo2O5+δthin films under O2and N2annealing atmosphere arec-axis oriented with the interface relationship of [100]LBCO//[10LAOand (001)LBCO//(001)LAO. Annealing the film in N2ambient significantly increases the resistivity and magnetoresistance comparing to the films annealed in O2ambient. The magnetoresistance after annealing in N2is almost more than twice of the magnetoresistance after annealing in O2. The result revealed that the electrical properties of the film are highly influenced by annealing atmosphere, indicating that the physical properties can be controlled by adjusting the post annealing atmosphere.
Physical and Antimicrobial Characterization of Self Assembled Silver Nanoparticle/Chitosan onto Low Density Polyethylene Film as Active Packaging Polymer
Authors: Jokar Maryam , Rahman Russly Abdul , Abdullah Luqman Chuah
Published: March 2014

Colloidal Silver nanoparticles with a size of 5 nm produced by chemical reduction using poly ethylene glycol (PEG 200). Layers of silver nanoparticles and chitosan were deposited onto low density polyethylene (LDPE) substrate by layer by layer (LBL) self-assembly technique. Silver nanocomposite films were built by sequential dipping of LDPE film in either anionic silver nanoparticles or cationic chitosan. Silver nanoparticles and chitosan led to the formation of nanocomposite films possessing antimicrobial properties with the thickness of 2, 4, 8, 12 and 20 layers. Silver nanocomposite films were characterized by atomic force microscopy (AFM). Thermal, mechanical and barrier properties of LBL deposited nanocomposite films were investigated. Results showed that the LBL deposition of silver nanoparticles and chitosan increased the crystallinity of the composites and also improved mechanical and barrier properties of LDPE film significantly (p<0.05). Antimicrobial activity of silver nanocomposites againstEscherichia coliandStaphylococcus aureuswas evaluated. Growth kinetic parameters ofE.coliandS.aureusaffected by silver nanocomposites were calculated by modeling of absorbance data according to Gomperz equation. LDPE-silver nanocomposite affected bacterial growth parameters significantly (p<0.05). The specific growth rate reduced from 0.30 to 0.11 h-1forE. coliand decreased 0.27 to 0.06 h-1forS. aureus.
Antheraea pernyi Silk Fibroin Nanoparticles for Drug Delivery
Authors: Lu Shen Zhou , Wang Juan , Mao Li , Li Gui Jun , Jin Jian
Published: March 2014

Silk nanoparticles were easily obtained from regenerated Antheraea Pernyi Silk Fibroin (ASF). The morphology and average size of the silk particles was sensitive to pH value of fibroin solution. The diameter of nanoparticles prepared was in the range of 30 nm to 1000 nm with a narrow size distribution. On this process, the molecular conformation of regenerated ASF changed from α-helix to β-sheet structure. The shape of prepared nanoparticles were regular spherical structure when the pH value was about 4.3 (pI) in ASF solution. Doxorubicin hydrochloride (DOX) was loaded in the ASF particles as drug release model and the drug-loading ratio was 3.4 %. The release rate of DOX from ASF nanoparticles was pH sensitive. After 23 days release, there was still 84% DOX in the ASF nanoparticles. The result suggested that the ASF nanoparticles might be suitable microcarriers for drug delivery.
PEG Functionalized Gold Nanoparticle Loaded PLGA Films for Drug Delivery
Authors: Dixon D. , Meenan B.J. , Manson J.
Published: March 2014

A novel composite of poly (ethylene glycol) (PEG) functionalized gold nanoparticles (AuNP-PEG) dispersed within Poly (lactic-go-glycolic) (PLGA) films, were prepared to demonstrate the concept of a combined targeted and sustained implant material. This technology offers the promise of improved therapies for difficult to treat tumors such as Gliomas. Gold nanoparticles (AuNPs) synthesized via a modified Turkevich method, were functionalized with thiol terminated polyethylene glycol (PEG), washed using centrifugation, dried, re-suspended in a solution of PLGA in dichloromethane and finally vacuum dried to produce the solvent cast films. The degradation and nanoparticle release profile of these films were studied by immersion in PBS media at 37 °C over periods of up-to 58 days. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was conducted. The release of the AuNPs-PEG nanoparticles during degradation was studied using inductively coupled plasma mass spectroscopy (ICP-MS). It was observed that the AuNP-PEG nanoparticles were individually dispersed within the PLGA and that their addition extended the degradation time of the PLGA film, but did not appear to alter the nature of degradation. The nanoparticle release from the composite films displayed an approximately zero-order release profile.
Modeling and Measurement of the Effective Young Modulus of Porous Biomedical Materials Manufactured via SLM
Authors: Joguet David , Danlos Yoann , Bolot Rodolphe , Montavon Ghislain , Coddet Christian
Published: March 2014

Selective Laser Melting (SLM) has become a widely used process for manufacturing metal part prototypes. This process, also known as additive manufacturing or rapid prototyping, allows the production of complex pieces using a layer by layer technology. Each layer is build by a laser irradiation providing a local melting (and resolidification) of a thin powder bed presenting a thickness of a few tens of microns. In the present work, two different materials used in biomedical applications were processed by SLM (namely pure titanium and Co28Cr6Mo alloy). The process parameters were set in order to adjust the materials porosity levels. The influence of the porosity level on the material effective mechanical properties was then quantified by experimental measurements using a two point bending test and by applying numerical modeling. The numerical model is based on the use of cross-sectional SEM micrographs of the material. These micrographs were used as meshes (each pixel is a FEM element) and the ANSYS software was then used to perform virtual loadings on the material with the objective to provide its effective mechanical properties. A comparison of the predicted and measured Young modulus was then performed. The provided results confirm that the process parameters may be adjusted in order to control the porosity level of the material and subsequently to adjust its effective mechanical resistance.
Relationships between Microstructural and Mechanical Properties of Plasma Sprayed AlSi-Polyester Composite Coatings: Application to Abradable Materials
Authors: Duramou Yann , Bolot Rodolphe , Seichepine Jean Louis , Danlos Yoann , Bertrand Pierre , Montavon Ghislain , Selezneff Serge
Published: March 2014

Abradable coatings are widely used within aeroengines. These materials are applied onto the inner surface of compressor and turbine shroud sections using thermal spray processes, coating the periphery of the blade rotation path. The functionality of an abradable seal is to wear preferentially when rotating blades come into contact with it, while minimizing the over-tip clearance, and improving the overall efficiency of the engine. This study is concerned with the relationships between the microstructure and mechanical properties of atmospheric plasma sprayed AlSi-Polyester composite coatings.
Microstructure and Mechanical Properties of Al-Mn Sheets with Zr Addition
Authors: Vronka Marek , Karlík Miroslav
Published: March 2014

The aim of the experiments was to study the influence of the rolling reduction in thickness on the size and distribution of secondary particles and recrystallization behaviour of Al-Mn sheets with Zr addition prepared by twin-roll casting (TRC) in the industrial conditions. Samples, cold rolled on a laboratory mill, were subjected to a one and two-step precipitation annealing. Their microstructure (grain structure, phase composition, particle analysis) and mechanical and physical properties (microhardness, electrical conductivity) were then characterized. Quantitative particle analysis was carried out on field-emission gun scanning electron microscope (FEG-SEM) micrographs.
Structural, Electrical and Dielectric Properties of DC Reactive Magnetron Sputtered ZrO2 Films for Metal-Oxide-Semiconductor Devices
Authors: Kondaiah P. , Uthanna S.
Published: March 2014

Thin films of zirconium oxide (ZrO2) were deposited by DC magnetron sputtering of metallic target of zirconium on to quartz and p-Si (100) substrates at various oxygen partial pressures in the range 2x10-2 - 6x10-2 Pa. The crystallinity, surface morphology and optical absorption of the films were influenced by the oxygen partial pressure. X-ray photoelectron spectroscopic studies revealed that the films formed at oxygen partial pressure of 4x10-2 Pa were of stoichiometric ZrO2. X-ray diffraction profiles indicated that the grown films were of nanocrystalline with crystallite size increased from 5 nm to 9 nm with increase of oxygen partial pressure from 2x10-2 Pa to 6x10-2 Pa. The optical band gap of the films increased from 5.65 to 5.80 eV and the refractive index increased from 2.02 to 2.08 with the increase of oxygen partial pressure from 2x10-2 to 6x10-2 Pa respectively. The fabricated MOS structure with the configuration of Al/ZrO2/p-Si showed the dielectric constant of 22 and leakage current density of 1x10-6 A/cm2.
Modeling and Simulation of Plasmonic Nanoparticles Using Finite-Difference Time-Domain Method: A Review
Authors: Rajeswari R. , Jothilakshmi R.
Published: March 2014

In recent years, plasmonic nanoparticles are widely used in a wide range of applications including, biomedicine, spectroscopy, catalysis and energy harvesting. The properties of these particles are due to the interaction of these particles with electromagnetic irradiation that gives rise to the localized surface plasmons that are collective oscillations of their surface conduction electrons. This interaction influences its light absorption and scattering and thus, the particle color. Simulation of particle plasmons can be done by solving Maxwells equations for metallic nanoparticles embedded in a dielectric environment. One of the approaches to solve Maxwells equation is by Finite Difference Time Domain (FDTD) approach. Since FDTD is a time domain approach, the response for a wide range of frequencies can be obtained with a single simulation. In this paper we propose to review the application of FDTD in the simulation and modeling of various plasmonic nanoparticles.
Synthesis, Surface Acidity and Photocatalytic Activity of WO3/TiO2 Nanocomposites – An Overview
Authors: Prabhu S. , Nithya A. , Mohan S. Chandra , Jothivenkatachalam Kandasamy
Published: March 2014

Titania has been studied to be one of the best photocatalysts for the decomposition of many organic pollutants present in aqueous medium. Because of the wide band gap energy of TiO2 (3.2 eV) it can be activated only under UV light region which is present 4 % in the solar light spectrum. The photocatalytic activity of TiO2 was enhanced by means of several methods. TiO2 coupled with other semiconductor has gained additional importance, owing to improving the efficient charge separation by trapping the photogenerated electrons. WO3 is a better semiconductor having relatively lower band gap energy (2.8 eV) and absorb broad solar light spectrum. The formation of WOx monolayer on TiO2 notably increases the surface acidity of TiO2. This increasing the surface acidity of WO3/TiO2 photocatalyst facilitates the adsorption of the more hydroxyl group in addition to more organic reactants on its surface which obviously facilitate the enhancement of photocatalytic activity. In this review, the synthesis methods and photocatalytic activity of some selected and unique results related to WO3/TiO2 photocatalyst were discussed. The efficient charge separation, increased absorption of the reactants by increasing the surface acidity and high aspect ratio structures of WO3/TiO2 are also reviewed.
Effect of Substrate Temperature on the Structural and Electrochromic Properties of Mo Doped WO3 Thin Films
Authors: Madhavi V. , Kondaiah P. , Uthanna S.
Published: March 2014

Thin films of Mo (1.3 at.%) doped WO3 films were deposited on glass and ITO coated glass substrates held at substrate temperatures in the range 473 673 K by RF magnetron sputtering technique. The effect of substrate temperature on the structural and morphological, and electrochromic properties of the deposited films were investigated by X-ray diffraction, scanning electron microscope, Raman spectroscope and with electrochemical cell. X-ray diffraction profiles showed that the films formed at substrate temperature of 473 K consisted of weak (020) reflection related to the orthorhombic phase of WO3 in the amorphous matrix. The films formed at substrate temperatures 473 K were of polycrystalline in nature. The crystallite size of the films increased from 12 to 43 nm with increase of substrate temperature from 473 to 673 K. The scanning electron microscope images of the films formed at 473 K showed the leaf like structure with grain size of 1.2 μm. When substrate temperature increased to 573 K the size of the grains enhanced to 2.4 μm. Raman spectra of the films confirmed the presence of characteristic vibration modes of W = O, W - O - W and O - W - O. The optical band gap of the films increased with increase of substrate temperature. The electrochromic property, that is the color efficiency increased from 42.5 to 50.5 cm2/C with the increase of substrate temperature from 473 to 673 K respectively. The structural and electrochromic properties of the Mo doped WO3 films will be correlated with the substrate temperature maintained during growth of the films.
Simulation of Electron Injection and Charging Processes in Ferroelectrics Modified with the SEM-Techniques
Authors: Maslovskaya Anna , Sivunov Anton V.
Published: March 2014

The paper presents results of a computer simulation of dynamic processes caused by electron injection and charging-up effects in ferroelectrics irradiated by electron bunches with average energy. The implementation of electron transport simulation in ferroelectrics was performed by Monte-Carlo method to express the initial volume charge distribution. The calculation of charging characteristics was based on solution of Poisson equation using finite element method. The calculated distribution of potential as well as field intensity electron beam-induced for model sample were analyzed at given experimental parameters.
Nonlinear Optics with Backward Waves: Extraordinary Features, Materials and Applications
Authors: Popov Alexander K. , Slabko Vitaly V. , Shalaev Mikhail I. , Nefedov Igor. S. , Myslivets Sergey A.
Published: March 2014

Extraordinary properties of nonlinear-optical propagation processes are investigated that involve electromagnetic or elastic waves with negative group velocity. Nanostructured materials that support such waves and prospective unique photonic devices are described.
Syntheses and Structural Control of Silicide, Oxide and Metallic Nano-Structured Materials
Authors: Tatsuoka Hirokazu , Li Wen , Meng Er Chao , Ishikawa Daisuke , Nakane Kaito
Published: March 2014

The structural control and morphological modification of a series of silicide, oxide and Ag metal nanostructures have been further discussed with reviews of nanostructure syntheses, such as CrSi2 nanowire bundles dendrites, MoSi2 nanosheets, α-Fe2O3 nanowires nanobelts, CuO/Cu2O nanowire axial heterostructures, ZrO2/SiOx and CrSi2/SiOx core/shell nanowires. In addition, the syntheses of Ag three-dimensional dendrites, two-dimensional dendrites, two-dimensional fractal structures, particles and nanowires also were discussed. Moreover, the structural and morphological properties of the nanostructures were examined. The structural control and morphological modifications of the nanostructures have been successfully demonstrated by the appropriate thermal treatments with specific starting materials. A large volume of silicide nanowire bundles, large area of oxide nanowire arrays and large area Ag nanostructure coatings were successfully fabricated.