bluuebunny/crossref_metadata_2025 huggingface dataset:
Static Balancing of Mechanical Systems Used in Medical Engineering Field – Continuous Balancing
Authors: Ciupitu Liviu , Simionescu Ion , Olaru Adrian
Published: February 2012

In medical field are used many categories of mechanical systems, from simple mechanisms to the complex mechatronic systems. Present paper is focused to those mechanical systems that are working in vertical plane by supporting loads or by lifting weights. The targets are both patients and medical workers. Paper is proposing some new devices and mechanisms for supporting the weights that are hanged to the ceiling. These mechanical systems are called too with zero-stiffness because the balancing force does not depend to elongation of elastic system. For all the presented solutions the balancing of the weight forces will be done by using the elastic forces of torsion spiral springs and cylindrical helical springs with straight characteristics. The balancing is made exactly for all positions throughout the work field.
The Application of Learning Impedance Control to Exoskeleton Arm
Authors: Liu Jie , Wang Yu , Tong He Ting , Han Ray P.S.
Published: February 2012

In this paper, we discuss the application of learning impedance control scheme to exoskeleton arm driven by pneumatic artificial muscles (PAM), for assisting in the rehabilitation of patients who suffer from debilitating illness. An iterative learning impedance control problem for robotic manipulators is analyzed, proposed and solved. The target impedance reference modifies a desired trajectory according to the force signals and position signals of the joint. The desired control input of learning impedance control was estimated by radial basis function (RBF) neural network incorporated experience database. The curves of experiment result on the experimental setup show that the algorithm is successful also in the application of exoskeleton arm.
A New PSO-RBF Model for Groundwater Quality Assessment
Authors: Zhang Bi , Wang Jia Yang , Zhang Su Lan
Published: February 2012

There are three adjustable parameters in the radial basis function, the center of the basis function cj, the width parameter and the output unit weight wj. Through optimization the parameters of the radial basis function by Particle swarm optimization algorithm, a neural network model of underground water is generated, which is used to study the grade of underground water in the ten monitoring points of the black dragon hole. By applying the PSO-RBF model to underground water assessment in the ten monitoring points of the black dragon hole, the results of this evaluation, which correspond with the real conditions, are basically in accord with those obtained by other evaluation methods, and also show the practicability to groundwater quality assessment.
A Virtual Geographic Environment for Simulation Analysis of Dam-Break Flood Routing
Authors: Zhu Jun , Li Yi , Hu Ya
Published: February 2012

Dam-break flood affected by highly changing and complex environment, has some characteristics including the sudden of occurrence, the rapid of expansion and the urgency of respond. This paper focuses on how to develop a virtual geographic environment (VGE) system to study the dam-break flood routing and its impact. Unlike existing work, our methods pay attention to the multidimensional and dynamic analysis methods in virtual geographic environment, which make flood routing easily understood to public and officers. Moreover, some GIS spatial analysis and real-time interactive operation with the VGE will also be implemented to support the risk assessment of the dam-break. Finally, a prototype system is developed to construct a virtual geographic environment for impact analysis of dam-break flood routing and dynamic interaction. Experimental results prove that the scheme addressed in the paper is effective and feasible.
Investigation of Radon in Campus Air
Authors: Weng Mi Li
Published: February 2012

Radon concentration in the campus is important for the assessment the pollution level for the people. In this paper, the radon concentration inside the campus, such as in the dormitory, classroom and library were carefully analyzed with the continuous radon analyzer (Sun Nuclear 1027, USA). The results showed all the values were all in safe scope. In the dormitory, the maximum of the concentration of radon was 44.4 Bq/M3, with the minimum value of 33.3 Bq/M3. While in the library, the radon values in the library air were between the 44.4 Bq/M3 and 51.8 Bq/M3. And in the classroom, the results were between the18.5 Bq/M3 and 37.0 Bq/M3 , which were mostly around the 20s value and the average value was 25.6 Bq/M3.
Study of Electronic Structures and Transport Properties on Saturated GaN Nanowires
Authors: Li En Ling , Zhu Peng Fei , Zhao Tao , Ma De Ming , Wang Xue Wen
Published: February 2012

Geometry structure, electronic structure and electronic transport properties of saturated hexagonal single crystalline GaN nanowires in the [001] growth direction have been investigated based on generalized gradient approximation (GGA) of density functional theory (DFT) and non-equilibrium green's function (NEGF) method. The results show, there is a contraction of the bond lengths of the saturated GaN nanowires after optimization; the nanowires have direct band gap, and band gap decreases with the increase of the cross section of nanowires; the electronic density of state and electronic transmission spectra of two-probe system have their own pulse-type sharp peaks with almost the same location of electron energy; the curves of I-V characteristics of the three saturated GaN nanowires are symmetric over the entire bias-voltage range, and they are semiconducting.
Preparation, Electrical Conductivity, Photocurrent and Wettability of Carbon Microcoils
Authors: Sun Bin , Yin Hong Xing , Li Meng Meng , Long Yun Ze , Gu Chang Zhi
Published: February 2012

In this paper, we report on fabrication and physical properties of carbon microcoils, which are prepared by a chemical vapor deposition (CVD) process with Ni-catalyzed pyrolysis of acetylene, and characterized by a scanning electron microscope, a transmission electron microscope and an infrared spectrometer. The dark electrical conductivity of an isolated carbon microcoil is about 81 S/cm at room temperature, and its temperature dependence follows three-dimensional Mott variable-range hopping (VRH) model. Particularly, evident photocurrent is observed in the carbon microcoil upon cameral flash illumination. In addition, it is found that the surface of microcoil film is hydrophobic, showing a large water contact angle of about 135°. These results indicate that carbon microcoils have excellent physical properties, and can be used as optoelectronic and reinforced materials.
The Fabrication and Property of PTFE-NP Liquid Marbles
Authors: Wang Shao Peng , Yu Bing , Cong Hai Lin , Bai Xue
Published: February 2012

Liquid marbles are hydrophilic liquid drops encapsulated with hydrophobic powder materials. The liquid marbles have potential applications in drug delivery, water purification, ferrofluidic device and sensor microfabrication. In this work, a new type of polytetrafluoroethylene nanoparticle (PTFE-NP) liquid marbles were fabricated successfully using mixing method. The morphology of the formed liquid marbles was characterized under different conditions, and novel properties of the PTFE-NP liquid marbles were investigated and demonstrated.
Optical and Structural Properties of Yb-Doped ZnO Thin Waveguide Films with Er+ Ions Implantation
Authors: Qi Jun He , Wang Feng Xiang , Lu Fei , Qin Xin Feng , Liu Zhao Hong , Yang Guang , Li Li Juan , Chen Zhi Hua , Song Hong Lian
Published: February 2012

Yb-doped ZnO optical waveguide thin films were deposited on sapphire substrates by radiofrequency (RF) magnetron sputtering technology, and then Er+ions with the energy of 200 KeV were implanted into the as-deposited films, the implantation dose was 1×1015ions/cm2. Optical waveguide properties and film thicknesses were studied by prism coupling method. Film thicknesses, element components and Er+ions range distrbution were studied by Rutherford backscattering (RBS) technique. The basic structure and phase of the films were studied using X-ray diffraction (XRD). The properties of optical frequency upconwersion were investigated by fluorescence spectrometer. The results demonstrated that the Yb-doped ZnO films with Er-implantation have planar waveguide structure and the waveguide properties were changed compared with the virgin ZnO films. The effective refractive indices of the films decreasing with the amount of Yb-doped concentration increasing. Yb concentration in films associated with targets but more than that in them. The films shown the classic structure of c-axis preferred orientation. The compounds of Yb:Zn and Er:Zn were appeared in the films. Inspired the films by 980 nm laser in room temperature, stimulated optical emission between 300~720 nm was not observed.
Morphology-Controlled Synthesis of SiC Nanowires by Catalyst-Assisted Pyrolysis of Polymeric Precursor
Authors: Feng Wei , Ma Jing Tao , Ai De Sheng , Yang Wei You , Lin Xu Ping
Published: February 2012

Two different types of morphology are observed in synthesis of SiC nanowires by catalyst-assisted pyrolysis of polymeric precursor while Au acts as the catalyst. Both two types of SiC nanowires are well oriented and uniform in diameter. The results indicate that longer (~20 μm) and slimmer (~100 nm) nanowires are tends to be produced in high temperature (1450°C), while shorter (~10 μm) and thicker (200~300 nm) ones are tends to be produced in low temperature (1420°C). Then we make a discussion on the mechanism of the growth of SiC nanowires based on the VLS (Vapor-Liquid-Solid) process.
Solvothermal Synthesis of Nickel Glycolate Polymer and NiO Microtubes and Their Cr(VI) Absorbing Properties
Authors: Guo Chang Fa , Liu Yu , Hu Yong , Guo Hang Ming , Xie Yun Long
Published: February 2012

In this work, nickel glycolate polymer microtubes (NGPMs) were prepared via a facile solvothermal method using hydrous nickel nitrate and anhydrous sodium acetate as starting materials, and ethylene glycol as solvent. Furthermore, nickel oxide (NiO) microtubes were obtained by a high-temperature treatment of NGPMs in air atmosphere. The morphology and phase of the products were characterized by scanning electron microscope (SEM), Transmission electron microscope (TEM) and X-ray diffractometer (XRD). The results show that NGPMs are of hierarchical structure, which are composed of a lot of nanolamellas. The morphology of NiO microtubes directly derived from that of NGPMs. In addition, the experiments were conducted with atomic absorption spectrometer for adsorption of Cr2O72- in ultrapure water using these microtubes obtained as absorbers. The results reveal that NGPMs obviously possess a better ability of chromium absorption with a maximum absorbing value of 14.6 mg/g at pH of 4 than NiO microtubes. Thus, the as-prepared of NGPMs may be promising as a new type of absorber for heavy metal ion for water treatment.
Preparation and Physical Properties of ITO Thin Films by Spray Pyrolysis Method
Authors: Zhou Yang , Wu Guang Ming , Gao De Wen , Xing Guang Jian , Zhu Yan Ying , Zhang Zhi Qian , Cao Yang
Published: February 2012

Indium tin oxide (ITO) films were deposited on glass substrates by using the homemade spray pyrolysis system. Orthogonal test was designed to examine the optimal conditions for preparation of the ITO films. The results showed that the ITO thin films can be prepared by the homemade spray pyrolysis device successfully. The device is simple in structure and easy to use. The substrate temperature is the main factor on the photoelectric properties of the ITO films. The optimal conditions for preparing the ITO thin films were as following: the substrate temperature is 300oC, the carrier gas flow of the air was 1.5 L•min-1, the annealing temperature was 500oC, the proportion of the indium and tin was 10:1, the distance between substrate and nozzle was 8 cm, and the deposition time was 3.5 min. The average optical transmittance in the visible range and sheet resistance of the ITO film were 93% and 2786Ω/□, respectively.
Fabrication of Nano-Strctures on PEDOT:PSS Film by Nanoimprint Lithography
Authors: Li Jian Ying , Yu Hao , Wen Juan Juan , Li Zhi Dong , Xu Zhen Cheng , Zhang Ya Feng , Yu Hang , Lu Bing Rui , Liu Ran , Chen Yi Fang
Published: February 2012

It is very hard to fabricate nano-strctures on PEDOT:PSS film by conventional Nanoimprint Lithography for its non-thermoplastic property. Here we demonstrated a new nanoimprint process to pattern the PEDOT:PSS film at low temperature and low pressure by adding proper amount of Glycerol into PEDOT:PSS solution and pressing the Si-mold into Glycerol-PEDOT:PSS film under a pressure of 6.2Mpa for 45min at 80°C. We also compared our result to L. Tan and co-workers’. They found that positive replica was left on PEDOT:PSS film after pressing the Si-mold into Glycerol-PEDOT:PSS film under a pressure of 10Kpa for 5min at 80°C, but our work showed negative replica formed. Pressing time maybe is the critical reason to explain the different results. Holding the pressure longer gave the PEDOT:PSS enough time to flow into Si-mold and also gave Glycerol enough time to evaporate so that PEDOT:PSS became strong enough when separated the Si-mold from the PEDOT:PSS film. At last, Roman spectra was measured to confirm adding glycerol to PEDOT:PSS will not influence its molecular structure.
The Effect of Nano-SiO2 Addition on Electrical Properties of the Thermoelectric Compound Ca3Co4O9
Authors: Sun Wei Wei , Fan Wen Hao , Chen Shao Ping , Li Yi Yun , Meng Qing Sen
Published: February 2012

Abstract. Ca3CO4O9/x wt.%SiO2 composites were prepared by using field-activated pressure-assisted synthesis(FAPAS) process. The effects of nano-SiO2 addition on the microstructure and thermoelectric properties of the Ca3CO4O9 were investigated. With an increasing of the of SiO2 content, the size of Ca3Co4O9 particles decreased. The Seebeck coefficient decreased after the doping of nano-SiO2. The electrical conductivity firstly increased and then decreased with increasing amount of nano-SiO2 and the highest value belong to the Ca3CO4O9/0.5 wt.% SiO2 - sample. With the highest electric conductivity and slightly decreased Seebeck coefficient, the Ca3CO4O9/0.5 wt.%SiO2-sample achieved the highest power factor of 0.349 mw/mk2 at 800 °C, which is 8% higher than the value of pure Ca3CO4O9 reported in the literature.
Photocatalytic Degradation of Water-Soluble Azo Dyes by LaFeO3 and YFeO3
Authors: Wang Xue Juan , Shen Hai Yun , Tian Hai Yan , Yang Qiu Hua
Published: February 2012

Perovskite-type oxides LaFeO3 and YFeO3 were prepared by the citrate method. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared spectrometer (IR), ultraviolet visible spectrometer (UV). The results show that complex oxides LaFeO3 and YFeO3 have stable perovskite structure. The mean particle diameter of YFeO3 is about 30~40 nm, while LaFeO3 is about 50~60 nm. Photocatalytic degradation experiments of azo dye acid red 3B were done using perovskite-type oxides LaFeO3 and YFeO3 as photocatalysts. Dye Acid Red 3B solution with the LaFeO3 and YFeO3 undergone several degradation stages and the photodegradation rates were respectively 68.2% and 90.0% after irradiating 2 hours. The results show that the perovskite-type oxide YFeO3 has better photocatalytic activity, which mainly relates with the factors of position A such as the negative, the electronic structure, ion radius and so on.
Fast Synthesis of Rutile/Apatite Core/Shell Structured Photocatalyst in Simulated Body Fluid
Authors: Shi Fu Zhi , Li Yao Gang , Wang Hong Zhi , Zhang Qing Hong
Published: February 2012

The core/shell structured rutile/apatite was prepared by soaking rutile TiO2 (R-TiO2) microspheres into a simulated body fluid (SBF) only for 1 day. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) and N2 adsorption measurements. XRD showed that the apatite content increased with prolonging the soaking time or increasing the SBF concentration. TEM and EDX demonstrated that apatite had been coated on the surface of R-TiO2 microspheres successfully. HRTEM indicated that the lattice spacings of 0.27 nm and 0.32 nm were assigned to (211) plane of apatite and (101) plane of R-TiO2, respectively.
Cutoff Frequency Study on Nanocrystalline FeNbB Thin Films
Authors: Jiang Xiao Long , Yao Y.J. , Lai M. , Peng K. , Du Y.W.
Published: February 2012

A series of nanocrystalline FeNbB films were fabricated using ion-beam sputtering technique from FeNbB target. Pieces of these films were annealed for 1 hour at various temperatures up to 5730C. Room temperature soft magnetic properties of these films were measured. The influence of microstructure on magnetic behavior in nanocrystalline FeNbB films is investigated in a series of specimens with different film’s thickness. For the sample 120nm and 5000C annealed, cutoff frequency was found to be 5E7 Hz, which has the μf0=5E10.
Synthesis and Characterization of Y2O3 Nanoflowers
Authors: Zhan Shuang , Li Xia
Published: February 2012

The novel Y2O3 nanoflowers were synthesized through a facile hydrothermal method without using any catalyst or template. The phase composition and the microstructure of as-prepared products were characterized by field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD) as well as Fourier transform infrared spectrum. The formation mechanism for the Y2O3 flowers has been proposed.
Preparation of Sandwich-Like TiO2/Graphene/TiO2 Films and its Application in Photocatalysis
Authors: Wu Hong Peng , He Da Wei , Wang Yong Sheng , Yang Bing Yang , Xu Hai Teng , Li Jing Feng , Wang Hai Teng , Wang Ji Gang , Fu Ming
Published: February 2012

Anatase nano-TiO2 film was prepared by sol-gel method and graphene oxide nanosheets synthesized by Hummers method were deposited on this TiO2 thin film. Another nano-TiO2 film was then deposited on the graphene film forming sandwich-like to avoid graphene layer peeled off. Scanning electron microscope shows that TiO2 particles layer with a diameter of about 20 nm were densely and uniformly deposited on both surfaces of the graphene layer to form a sandwich-like composite structure. The composite films exhibit excellent photocatalytic degradation to methyl orange and remains chemically stable in the whole process without anything exfoliation.
Biodegradable Magnesium Alloys: A Review of Material Development and Applications
Authors: Persaud-Sharma Dharam , McGoron Anthony
Published: February 2012

Magnesium Based Alloys Possess a Natural Ability to Biodegrade due to Corrosion when Placed within Aqueous Substances, which Is Promising for Cardiovascular and Orthopaedic Medical Device Applications. these Materials Can Serve as a Temporary Scaffold when Placed in Vivo, which Is Desirable for Treatments when Temporary Supportive Structures Are Required to Assist in the Wound Healing Process. the Nature of these Materials to Degrade Is Attributed to the High Oxidative Corrosion Rates of Magnesium. in this Review, a Summary Is Presented for Magnesium Material Development, Biocorrosion Characteristics, as Well as a Biological Translation for these Results.
Effect of Biomimetic Nanocrystalline Apatite Surface on Bone Ingrowth
Authors: Gelber Jonathan , Hermida Juan C. , Patil Shantanu , Colwell Clifford W. , D'Lima Darryl D.
Published: February 2012

The Success of Hydroxyapatite-Coated Acetabular Components Has Not Been Consistent. Plasma-Sprayed Hydroxyapatite Coatings Work Well on Nonporous Substrates but Do Not Coat the Inner Surfaces of Open-Porous Substrates. Solution Deposition Can Generate Consistent Bioceramic Coats on Porous Surfaces that More Closely Mimic the Trabecular Pattern and Biochemistry at the Bone Interface. we Compared Bone Response to the Following Implants: Porous-Coated Ti6al4v Cylinders with 1 of 3 Treatments: Plasma Sprayed with Hydroxyapatite (HA), Coated with a Solution-Deposited Biomimetic Apatite Coating (BA), and Untreated (Control). Bilateral Femurs in 36 Rabbits Were Implanted with One of the above Implants. Bone Ingrowth for HA and BA Surfaces Was Significantly Higher than that for Control Surfaces. No Fragmentation or Debris Production Was Evident in the Apatite Coat of the BA Group. A Biomimetic Coat of Solution-Deposited Apatite May Be Resistant to Coating Delamination and Particle Generation.
Synthesis and Characterization of Sol-Gel Derived Hydroxyapatite-Bioglass Composite Nanopowders for Biomedical Applications
Authors: Adibnia S. , Nemati Ali , Fathi Mohammad Hosseien , Baghshahi S.
Published: February 2012

The main purpose of this study is to prepare and characterize hydroxyapatite (HA)–10%wt bioglass (BG) composite nanopowders and its bioactivity. Composites of hydroxyapatite with synthesized bioglass are prepared at various temperatures. Suitable calcination temperature is chosen by evaluating of the phase composition. X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM) techniques are utilized to characterize the prepared nanopowders. The bioactivity of the prepared composite samples is evaluated in an in vitro study by immersion of samples in simulated body fluid (SBF) for predicted time. Fourier transformed infrared (FTIR) spectroscopy and inductively coupled plasma (ICP) are used for evaluation of apatite formation and the bioactivity properties. Results show that HA-BG composite nanopowders are successfully prepared without any decomposition of hydroxyapatite. The suitable temperature for calcination is 600°C and the particle size of hydroxyapatite is about 40-70 nm. The apatite phase forms after 14 days immersing of the samples in SBF. It could be concluded that this process can be used to synthesize HA-BG composite nanopowders with improved bioactivity which is much needed for hard tissue repair and biomedical applications.
An Investigation of the Carriage Rate of Methicillin-Resistant Staphylococcus aureus in Pigs in the Western Province of Vietnam
Authors: Vo Thi Diem Thi , Mai Huynh An Doan , Ngo Hoa Thi , Nguyen Duong Thuy , Tran Thi Minh Tam
Published: February 2012

Methicillin-resistant Staphylococcus aureus (MRSA) transmission between pigs and humans can be a dangerous infection source for the community. To control and prevent such disease, MRSA research in healthy pigs has been conducted in the US and Holland. This paper reports the first such study in Vietnam. This study aims to optimize the method for investigating MRSA carriage in tonsil and nasal swabs of healthy pigs. Potential samples were selected rapidly by Multiplex PCR (M-PCR) assay with 3 primers (Staph 756, mecA, Sa442) and then combined with conventional methods to detect and pick up MRSA strains. These strains were grouped based on genome pattern by pulsed field gel electrophoresis (PFGE). This study showed that we successfully isolated MRSA and the rate of MRSA carriage samples was 3.63%, much lower than that reported in the USA (49%) and Holland (39%), however the USA and Holland studies investigated pigs from industrial scale piggeries, whereas our study investigated pigs from small farms, which is the usual approach to pig farming in Vietnam. The MRSA patterns identified and associated MRSA strains were different from identified MRSA strains in other countries. This research provides important information about the carriage rate of MRSA in pigs in the Western province of Vietnam and demonstrates the importance of ongoing investigations in this area.
Synthesis and Characterization of ZnO-SiO2/Epoxy Nanocomposite Coating by Sol-Gel Process
Authors: Farhadyar Nazanin , Sadjadi Mirabdullah Seyed
Published: February 2012

In this paper, we report preparation of hydrophilic hybrid nanocomposite coatings on glass substrates using Zinc acetate solutions based on 3-glycidoxypropyltrimethoxysilane (GPTMS), epoxy resin, aromatic amine (HY850), polyethylene glycol (PEG) and surfactant (polyoxyethylene(4)laurylether) by the sol-gel process. Furthermore, the effects of PEG addition to the precursor solutions on the hydrophilic property and microstructure of the resultant coating film were studied. The hydrophilic behavior study of the synthesized hybrid was performed by adding different amounts of polyethylene glycol precursor to the hybrid solution. Experimental results show that, among different amounts of PEGs, the best results are obtained by addition of PEGs (400) to the hybrid solution which can decrease the water contact angles down to 16 and using surfactant down to 0, and increase the free surface energy. Coated glass exhibits a higher strength than uncoated glass. Attenuated total reflectance infrared spectroscopic (ATR-IR) technique was used to characterize the structure of the hybrid films. The chemical structure of obtained network affects morphology of the coating. The morphology of the hybrid coatings was examined by transmission electron microscopy (TEM). The hybrid systems have a unit form structure and the inorganic phases were in the nanosize scale,
Synthesis and Characterization of Cu-10-20wt%Ni Nanopowders by a Chemical Precipitation Route
Authors: Roohibakhsh R. , Rezaie Hamid Reza , Razavizadeh Hekmat
Published: February 2012

In this research Cu-Ni nanostructure powders were prepared by using a chemical procedure including initial precipitating, calcining the precipitates and reducing the calcined powders. The influence of nickel contents on the characteristics of the synthesized powders was investigated. Copper and nickel sulfate and sodium hydroxide were used as raw materials. CuSO4.3Cu(OH)2, NiOOH and Ni(OH)2 precipitates were obtained by addition of sodium hydroxide into aqueous copper and nickel sulfate solution. Oxide powders were produced by calcinations of precipitates. Considering the information obtained from the TGA test, calcination was done on precipitates. Copper-nickel nanostructure powders were synthesized by reduction of calcined powders in a hydrogen atmosphere. Eventually powders were characterized by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Crystallite size of final synthesized powders was in the range of 30 to 33 nm.
Fabrication and Characterization of Si Nano-Columns by Femtosecond Laser
Authors: Ghalehbeygi Omid Tayefeh , Kara Vural , Trabzon Levent , Akturk Selcuk , Kizil Huseyin
Published: February 2012

We fabricated Si Nano-columns by a femtosecond laser with various wavelengths and process parameters, whilst the specimen was submerged in water. The experiments were carried out by three types of wavelengths i.e. 1030 nm, 515nm, 343nm, with 500 fs laser pulses. The scales of these spikes are much smaller than micro spikes that are constructed by laser irradiation of silicon surface in vacuum or gases like SF6, Cl2. The Si nano-columns of 300 nm or less in width were characterized by SEM measurements. The formation of these Si Nano-columns that were revealed by SEM observation, indicates chemical etching with laser ablation occurred when surface exposed by laser beam. We observed 200 nm spikes height at the center of laser beam profile and the ones uniform in height at lateral incident area.
In Situ Fabrication and Characterization of (NiCr)Al-Al2O3 Nanocomposite by Mechanical Alloying
Authors: Shirani-Bidabadi Amir Reza , Shokuhfar Ali , Enayati Mohammad Hossein , Biglari Mazda
Published: February 2012

In this research, the formation mechanisms of a (NiCr)Al-Al2O3 nanocomposite were investigated. The structural changes of powder particles during mechanical alloying were studied by X-ray difractometry (XRD) and the morphology and cross sectional microstructure of powder particles were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The methodology involved mechanical alloying of NiO, Cr, and Al with molar ratios of 3:3:8. During mechanical alloying, NiO was first quickly reduced by aluminum atoms to produce NiAl nanocrystalline and Al2O3. Subsequently, and when a longer milling time was applied, chromium atoms diffused into the NiAl lattice. The heat treatment of this structure led to the formation of the (NiCr)Al intermetallic compound as well as Al2O3 with crystalline sizes of 23 nm and 58 nm, respectively.
Synthesize and Characterization of Multifunctional Silica Coated Magnetic Nanoparticles Using Polyvinylpyrrolidone (PVP) as a Mediator
Authors: Sadjadi Mirabdullah Seyed , Fathi F. , Farhadyar Nazanin , Zare K.
Published: February 2012

Magnetic iron oxide nanoparticles with proper surface coatings are increasingly being evaluated for clinical applications such as hyperthermia, drug delivery, magnetic resonance imaging, transfection and cell/protein separations. In this work, silica coated iron oxide magnetic nanoparticles, which are very useful for delivering chemotherapeutic drugs, has been prepared by precipitation in an aqueous solution of iron (II) and iron (III) chlorides under basic condition. In this process, polyvinylpyrrolidone (PVP) has been used as a stablizer. Surface modifications of the as-prepared Fe3O4 Nps have been carried out by using tetraethoxysilane (TEOS). Silica coated nanoparticles have been characterized by Fourier transform infrared (FTIR) spectroscopy, Powder X- ray diffraction (XRD), Transmission electron microscopy (TEM) and Infrared (IR) spectroscopy
AgNPs Included GC/Poly [3, 4-Ethylenedioxythiophene] Modified Electrode Toward Electrochemical Detection of H2O2
Authors: Rad Ali Shokuhi , Ardjmand Mehdi , Jahanshahi Mohsen , Safekordi Ali-Akbar
Published: February 2012

An Ag nanoparticle included Glassy carbon (GC)/poly [3, 4-ethylenedioxythiophene] (PEDOT) modified electrode was organized by a straightforward electrochemical method without using any stabilizer or reducing agent. The obtained working electrodes showed a high conductivity when compared to the bare electrode. It also shows superior ability of electrochemically sensing towards the electroreduction of H2O2 with no need for an enzyme or mediator immobilized in the electrode. Under optimum condition the detection limit using chronoamperometry response was estimated to be 0.61 M based on the criterion of signal-to-noise ratio of 3 (S/N of 3).
Synthesis and Characterization of Si Nanoparticles Obtained on Sonication of Porous Silicon Multilayer Films
Authors: Kale Paresh G. , Pratibha Sharma , Solanki Chetan S.
Published: February 2012

Synthesis of Si quantum dots (QDs), useful for multi-junction crystalline Si solar cells, using porous Silicon (PS) is presented in this paper. Four types of freestanding PS structures are fabricated by anodization method with modulation of current density between two levels. The level-1 current density is kept constant at 20 mA/cm2 (for reference monolayer structure - sample A) and 10 mA/cm2 (for all multilayer structures samples B, C, D). The level-2 is varied between 0 to 50 mA/cm2 (0, 20, 30, 50 mA/cm2 as sample A, B, C and D respectively). In order to obtain Si QDs from PS films, the films are subjected to sonication (120 W, 42 kHz) for 6 hours. HRTEM images confirm presence of Si nanoparticles in the range of 2 to 8 nm. Various spectroscopic analyses of Si nanoparticles are performed in order to evaluate quantum confinement behavior and surface modification observed during sonication. Analysis of de-convoluted Raman peaks shows frequency downshift and increase in full width half maximum due to formation of QDs. After sonication, PL spectroscopy indicates blue shift from 2.54 eV (sample A) to 2.85 eV (sample D_6HR), similar to the observations made by UV-Vis spectroscopy. FTIR spectra show oxidation of Si QDs during sonication. Spectroscopic and microscopic results are explained using quantum confinement and surface modification phenomenon.
Al-Free Nanolayered Metallization Systems for Sub-Micron HEMTs
Authors: Kolaklieva Lilyana , Chitanov V. , Kakanakov Roumen
Published: February 2012

Al-Free Nanolayered Metallizations Based on the Transition Metals Ti, Mo, Ni and Pd, with Varied Ti Content, Have Been Developed as an Alternative of the Al-Based Contacts for Sub-Micron Hemts. the Electrical, Morphological and Thermal Properties of the Metallization Schemes Have Been Studied with the Aim of Obtaining the Most Suitable Combination of Low Resistivity, a Smooth Surface and an Acute Edge. the Lowest Resistivity of 8.8x 10-6 Ω.cm2 Has Been Determined with the Ti/Mo/Ti/Au Contact, while the Lowest Surface Roughness of 6 Nm Has Been Measured for the Ti/Ni/Ti/Au Metallization. these Contact Schemes Have Shown much Better Edge Acuity in Comparison to the Al-Based Metallizations.
Effects of Strain Rate and Grain Size on Behavior of Nano Crystalline Materials
Authors: Jafari Nedoushan Reza , Farzin Mahmoud , Mashayekhi Mohammad
Published: February 2012

Recent Experiments on Nano-Crystalline Materials Show an Increase of Strain-Rate Sensitivity in Contrast to the Conventional Coarse-Grained Materials. these Materials Also Show a Different Grain Size Dependency as Compared to Coarse-Grained Materials. to Explain these Issues, a Constitutive Equation Is Proposed which Considers Dominant Deformation Mechanisms Including Grain Interior Plasticity, Grain Boundary Diffusion and Grain Boundary Sliding. the Stresses Obtained from these Constitutive Equations Match Well with the Experimental Data for Nanocrystalline Copper at Different Strains and Strain Rates. the Model Also Well Predicts Variation of Strain Rate Sensitivity Parameter. this Variation Can Be Explained with Regard to the above Mentioned Effective Deformation Mechanisms. Deviation from the Hall-Petch Law and Inverse Hall-Petch Effect Are Also Well Illustrated by the Model.
Preparation and Characterization of Intermetallic Nanoparticles for Lithium Ion Batteries
Authors: Nwokeke Uche G. , Nacimiento Francisco , González José R. , Alcántara Ricardo , Tirado José L. , Pérez-Vicente Carlos
Published: February 2012

Nanoparticles based on tin compounds and alloys have been prepared by using the polyol and/or sonochemical methods. Thus, nanoparticulated Fe1-xCoxSn2 solid solutions were prepared by using the polyol method or, alternatively, a combination of the polyol and the sonochemical methods, and the Rietveld refinements of the XRD patterns confirm the formation of the solid solutions solutions. Pure or pyrolyzed polyacrylonitrile (PAN) can be used to create a matrix that encapsulate the metallic particles and improve the electrochemical cycling behavior. Thus, MSn2@PAN (where M=Fe or Co) have been prepared by using dimethylformamide like solvent of PAN and applying high-intensity ultrasonication to achieve small particle size, poor crystallinity and high dispersion. The very small particles of MSn2 exhibit higher tendency to be oxidized in air atmosphere than the larger particles. The very small particle size of the alloy and the organic phase (PAN) contribute to stabilize the interfaces and the contacts in the electrode, as is evidenced by the electrochemical cycling and the impedance spectra. A model is proposed for the electrochemical behavior of the MSn2@PAN electrode materials. MSn2@C materials can be prepared throughout the pyrolysis of the PAN molecules matrix.
Deposition of ITO Thin Films onto PMMA Substrates for Waveguide Based Biosensing Devices
Authors: Azevedo Sofia , Diéguez L. , Carvalho P. , Carneiro J.O. , Teixeira Vasco , Martínez E. , Samitier J.
Published: February 2012

Biosensors’ research filed has clearly been changing towards the production of multifunctional and innovative design concepts to address the needs related with sensitivity and selectivity of the devices. More recently, waveguide biosensors, that do not require any label procedure to detect biomolecules adsorbed on its surface, have been pointed out as one of the most promising technologies for the production of biosensing devices with enhanced performance. Moreover the combination of optical and electrochemical measurements through the integration of transparent and conducting oxides in the multilayer structures can greatly enhance the biosensors’ sensitivity. Furthermore, the integration of polymeric substrates may bring powerful advantages in comparison with silicon based ones. The biosensors will have a lower production costs being possible to disposable them after use (“one use sensor chip”). This research work represents a preliminary study about the influence of substrate temperature on the overall properties of ITO thin films deposited by DC magnetron sputtering onto 0,5 mm thick PMMA sheets.
Synthesis, Structural, Electrical, Magnetic and Dielectric Spectroscopic Characterization of C-Er2Si2O7
Authors: Ameer Shahid , Faraz Ahmad , Maqsood Asghari , Ahmad Nasir M.
Published: February 2012

The Polymorphic Er2Si2O7 Is Synthesized by Solid State Double Sintering Method. Structural and Morphological Characterizations Have Been Performed Using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The Electrical Characterization Has Been Performed by Two Probe Method as a Function of Temperature. the Dielectric Spectroscopic Measurements of Polymorphic Er2Si2O7 Are Performed in the Temperature Range 300-555 K and Frequency Range 3 kHz to 1 MHz. the dc Electrical Transport Data Are Analyzed According to Mott’s Variable-Range Hopping. The ac Conductivity σac(ω) Is Obtained through the Dielectric Spectroscopic Measurements. the ac Conductivity Obeys Power Law which Can Be Expressed as σac (ω) = B ωs, where S Is Slope and it Determines the ac Electrical Transport Phenomenon. the ac Electrical Transport Data and its Variation with Temperature in this Rare Earth Formulation Are Well Discussed. the Magnetic Behavior of Synthesized Material Is Analyzed and Confirmed that Material Have Non-Magnetic Behavior with Coercivity (Hc) 842 Oe. while the Values of Magnetic Saturation (MS) and Remanace (Mr) Were Found in Range 3.90emu/g and 1.07emu/g.
High Pressure Waterjets – An Innovative Means of Alpha Case Removal for Superplastically Formed Titanium Alloys
Authors: Chillman A. , Ramulu Mamidala , Hashish M. , Cantrell A.
Published: February 2012

Ultra high-pressure waterjets (WJ) have gained consideration as a viable alternative to conventional material removal and cleaning methods such as chemical milling, grit blasting, and grinding. Waterjets have often been considered for the stripping of unwanted coatings, but they also exhibit an inherent ability for the controlled milling of metallic materials. The waterjet material removal process poses a secondary benefit – the material erosion occurs due to the repetitive impact of droplets within the waterjet stream, which also serve to induce compressive residual stresses in the shallow sub-surface layers of the work piece. An experimental study was conducted to explore the removal of the alpha case layer on Superplastically Formed conventional and fine grain Ti-6Al-4V specimens. The resulting surface roughness parameters and completeness of alpha layer removal were characterized. Based on the experimental results, waterjet removal processes may serve as an alternate method for the post-processing of Superplastically Formed titanium alloys.
Superplastic Forming and Diffusion Bonding: Current Cost, Value and Future Trends
Authors: Wilson Paul , Couzins-Short Christopher , Chesterton Howard , Jocelyn Alan
Published: February 2012

Superplastic Forming and Diffusion Bonding (SPF/DB) have provided some of the lightest, strongest, corrosion resistant, elegant and complex structures ever produced. Thus “At Boeing, SPF is now considered as a baseline design option for many large assemblies” (Dan Sanders, 2000). However, in an ever increasingly cost conscience world, will the process flourish or decline?

Cost is the element most scrutinised by society, and is often considered more important than achieving a required specification or delivery of a project on time. In this paper an analysis of the global value of SPF and SPF/DB products will be provided by industrial sector and material type. The cost of the current technology, such as capital plant, consumable materials and labour overheads, will be compared to the current price of SPF products and the degree of ‘market pressure’ to reduce such costs will be assessed. Such pressures may arise from potential threats from competing technologies, fuel costs or environmental considerations.

However, if lowering the ‘carbon footprint’ of the process, and its cost, could be achieved, together with the production of components and structures of improved weight to strength ratio, SPF technology could be elevated to the first, and principal, choice of designers worldwide.
Contact Sensors for Accurate Monitoring and Prediction of Sheet Deformation during Hydro/Pneumatic Forming Operations
Authors: Abu-Farha Fadi K. , Nazzal Mohammed A. , Rawashdeh O. , Michael R.
Published: February 2012

In spite of the numerous advantages of hydro/pneumatic forming operations over the conventional mechanical ones, the inability to accurately monitor the progress, and determine the end point, of the process represents a major setback. Therefore, this effort presents a simple technique for providing a direct feedback on the sheet’s advancement during the process by implanting contact sensors across the surface of the forming die at selected locations. The technique is shown to be instrumental in providing a means of control over the process particularly for constant pressure forming practices and thus eliminating the need for any trial-and-error runs. More importantly, the light is shed on how the technique can be utilized to validate and improve the constitutive and Finite Element (FE) models of the unique class of lightweight alloys often formed by hydro/pneumatic operations; a matter essentially needed for constant strain rate forming practices.
Superplastic Behavior and Microstructure of Titanium (Ti-6Al-4V) Friction Stir Welds Made under a Variety of Processing Conditions
Authors: Edwards Paul , Ramulu Mamidala , Sanders Daniel G.
Published: February 2012

Friction Stir Welding of Ti-6Al-4V was performed on 5 mm thickness plate in order to assess the affect of welding conditions on the resulting microstructure and superplastic forming behavior of the joints. A variety of welding conditions were tested and all welds were subsequently Superplastically formed. It was found that the weld parameters do influence the microstructure and degree of superplastic performance of the joints. Spindle speed was found to have the most dominant affect on the resulting microstructure and superplastic forming behavior. Low spindle speed welds lead to fine grained microstructures and highly superplastic welds, relative to the base material, while high spindle speed welds larger grained microstructures and less superplastic welds.
Finite Element Modeling of Superplastic Forming of Tubular Shapes
Authors: Nazzal Mohammed A. , Abu-Farha Fadi K.
Published: February 2012

Most of the work done on superplastic forming is related to sheet metal forming. Very limited studies have been directed toward investigating the superplastic tube forming process. In this work, Finite Element (FE) simulations are carried out in order to simulate the superplastic tube forming process. The analysis is conducted for the superplastic magnesium alloy AZ31 at 400°C. The results clearly demonstrate that there is a significant difference between tube forming and sheet metal forming in terms of forming pressure profiles. In addition, the effects of tube radius, free forming length, and contact on the tube forming process are investigated.
High-Temperature Forming of a Vehicle Closure Component in Fine-Grained Aluminum Alloy AA5083: Finite Element Simulations and Experiments
Authors: Hector Louis G. , Krajewski Paul E. , Taleff Eric M. , Carter Jon T.
Published: February 2012

Fine-grained AA5083 aluminum-magnesium alloy sheet can be formed into complex closure components with the Quick Plastic Forming process at high temperature (450oC). Material models that account for both the deformation mechanisms active during forming and the effect of stress state on material response are required to accurately predict final sheet thickness profiles, the locations of potential forming defects and forming cycle time. This study compares Finite Element (FE) predictions for forming of an automobile decklid inner panel in fine-grained AA5083 using two different material models. These are: the no-threshold, two-mechanism (NTTM) model and the Zhao. The effect of sheet/die friction is evaluated with five different sheet/die friction coefficients. Comparisons of predicted sheet thickness profiles with those obtained from a formed AA5083 panel shows that the NTTM model provides the most accurate predictions.
New Developments in Superplastic Forming Simulation and Industrial Applications
Authors: Li Shun Ping , Chabin Mathilde , Heath Andrew
Published: February 2012

In this paper, the authors presented the material models and numerical algorithms adopted in PAMSTAMP 2G for superplastic forming simulation. The improvements in strain rate control, automatic stop criteria, velocity scaling and shell element formulation to include normal stress can improve the accuracy and efficiency of superplastic forming simulation.
The Role of the Numerical Simulation in Superplastic Forming Process Analysis and Optimization
Authors: Sorgente Donato , Tricarico Luigi
Published: February 2012

Numerical simulation took root in the last few decades in the superplastic forming field as one of the most dominant tools for process analysis and optimization. The big role of the simulation can be found in many areas concerning the study and the implementation of the forming process. The purpose of this paper is to outline some of the main applications of the numerical simulation in superplastic forming that can be found in the material characterization phase, in the simulation of forming tests and in the optimization of the process. A brief overview of results that can be found in literature is given with special regard to Finite Element numerical simulation of metal sheet Superplastic Forming.
Superplasticity in Friction Stir Processed AZ80 Magnesium Alloy
Authors: Takayama Yoshimasa , Takeda Itsuki , Shibayanagi Toshiya , Kato Hajime , Funami Kunio
Published: February 2012

Superplasticity in an AZ80 magnesium alloy subjected to friction stir processing (FSP) has been investigated. FSP was carried out at two traveling speeds of 150mm/min and 300mm/min for grain refinement. Optical microscopy on cross section to processing direction revealed obvious differences in size and feature between the stir zones at the two traveling speeds. The hardness of FSPed sample at the room temperature was about 30HV higher than that of as-received one. The maximum stress of the FSPed sample was reduced remarkably at lower strain rates compared with those of the as-received one at 573K and 673K. On the other hand, the elongation to failure of the FSPed sample showed ten to thirteen times larger than that of the as-received one at 573K and low strain rates. Further surface morphology near the fracture tip was observed by scanning electron microscopy to discuss deformation mechanism at high temperatures.