bluuebunny/crossref_metadata_2025 huggingface dataset:
Formulating Nanomedicines: Focus on Carbon Nanotubes as Novel Nanoexcipients
Authors: Foldvari Marianna
Published: June 2010

Many recently designed drug delivery systems have been constructed from nano-sized components that serve as the carrier or targeting ligand for a therapeutic agent. Even though these materials have been regarded previously as inert or non-active components of dosage forms, they are now recognized as sometimes being even more important than the drug itself. Hence, it is becoming increasingly imperative that the pharmaceutically relevant properties, including identity, physicochemical characteristics, purity, solubility and toxicity, of these functional nano-excipients be fully characterized. Carbon nanotubes (CNTs) are novel nanomaterials made of carbon atoms that have wide application potential in many areas of nanomedicine. However, because of their significant potential, CNTs, as building blocks for nanomedicines, need to be characterized more fully. Studies to date indicate that both physical and chemical properties of CNTs play an important role in their interactions with cells. Therefore, a full understanding of the physical properties of CNTs, such as identity, chirality, particle size, aspect ratio, morphology and dispersion state, as well as chemical properties such as purity, defect sites and types and functional groups, will be essential to develop a full characterization panel of these versatile nanomaterials.
Driving Forces and Consequences of the Adsorption of Proteins to Carbon Nanotubes
Authors: Mora María F. , Valenti Laura E. , García Carlos D. , Giacomelli Carla E.
Published: June 2010

Different strategies used to biofunctionalize CNTs with proteins, from direct physical adsorption on pristine CNTs to chemical treatments to achieve covalent interaction, are described. The discussion is focused on the consequences of the adsorption process on the structure and properties of both proteins and CNTs. On this base, recent developments in CNTs-proteins based biosensors (electrochemical and optical) and drug delivery systems are reviewed.
Electrochemical Nanostructuring of Semiconductors by Capillary-Cell Method
Authors: Taurbayev Y.T. , Gonchar K.A. , Zoteev A.V. , Timoshenko Victor , Zhanabayev Z.Zh. , Nikulin V.E. , Taurbayev T.I.
Published: June 2010

Wafers of silicon and compound semiconductors are nanostructured by using electrochemical or chemical etching (stain etching) in etching cell with electrolyte kept by capillary forces. Atomic force microscopy, infrared spectroscopy and Raman scattering methods reveale nanoporous and nanocrystalline structure of the treated surfaces. The formed porous semiconductors demonstrate efficient photoluminescence, which is controlled by etching parameters, i.e. current density, electrolyte content, etc. These results indicate good prospects of the employed capillary-cell method for preparing nanostructured porous materials with desired structure and optical properties.
Tailoring of Multiferroic Properties of BiFeO3 Thin Films by Cation Substitution
Authors: Awan M.S. , Bhatti A.S. , Qing S. , Ong C.K.
Published: June 2010

Mn-doped multiferroic BiFeO3 (BFMO) thin films were deposited on LaNiO3(LNO)/SrTiO3(STO)/Si(100) substrates by pulsed laser deposition (PLD) technique. X-ray diffraction (XRD) showed that films were bicrystalline single phase with (110) preferential orientation. Multiferroic top layer and oxide bottom electrode (LNO) epitaxially followed the buffer layer (STO). Oxygen partial pressure during deposition proved to be critical for phase formation, crystallinity and resistivity of the films. Atomic force microscopic (AFM) studies revealed the smooth, dense and crack free surfaces of the films. Cross-section view of the multilayers by field emission scanning electron microscope (FE-SEM) gave their thickness. Mn substitution resulted in the increase of magnetization saturation, coercive field and clarity of hysteresis loop. The magneto-electric (ME) effect was demonstrated by measuring the dielectric response in a varying magnetic field. Optimally deposited BFMO films show saturated P-E loop.
An Investigation into the Effects of Substrate Temperature on Magnetic Properties of RF Sputtered NiFe Films
Authors: Akhtar Pervez , Ali T.J. , Mahmud R.
Published: June 2010

The paper describes results of investigation on sputtered NiFe Films to determine the sputter deposition condition that could produce magnetic field sensors with the desired magnetic properties. The magnetic materials used in such devices should have a low coercive force, a low anisotropy field and a low magnetization dispersion, α50. .The results of systematic investigation of radio-frequency (RF) sputtered, RF biased, 82-18 % NiFe films showed (i) Improved Kobelev methods were applied to magneto-optic measurement techniques, suppress the magnetization ripples when subjected under the application of dc field. (ii) Anisotropy field results indicated an inverse trend with increasing substrate temperature (iii) the experimental measurements on magnetization dispersion relatively constant up to 200 °C with α50 approximately 1.2°, it then increases more sharply to about 3.5° at 400 °C substrate temperature. The work also provide understanding of the effects on the magnetic properties of sputtered magnetic films that is very limited as current literature is almost entirely limited to evaporated magnetic films.
Synthesis of Multiwall Carbon Nanotube and their Thin Films for Infrared Sensor Applications
Authors: Mansoor M. , Siddique S. , Asim M.M.
Published: June 2010

Catalytic synthesis of carbon multiwall nanotubes (MWCNT) was carried out by chemical vapor deposition. Synthesis temperature was 750oC, whereas, iron nitrate and ethanol was used as catalyst and carbonaceous source, respectively. The carbon nanotubes produced were multiwall and tangled in nature with nominal diameter of 50nm and length 2.5µm. These MWCNTs were purified by an acidic treatment and subsequently functionalized by chemical oxidation. After synthesis and functionalizing, a thin film of MWCNT was deposited on quartz substrates which were coated with copper electrodes. Investigations showed that during film preparation a bridging of CNTs was established between the copper electrodes which were further revealed to be semi-conductive by current Vs voltage testing. The discernable characteristics included batter conduction and infrared photocurrent responses.
Structural and Texture Studies of PbS Thin Film
Authors: Mehmood S.K. , Zaman S. , Ahmed K. , Asim M.M.
Published: June 2010

In this study, we report on the structural parameters and texture development which occurred during deposition and annealing of PbS films and their effect on optical properties. The films under study were deposited on glass substrates through chemical bath method. The reactive substances used to obtain the PbS layers were lead accetae trihydrated, thiourea and hydrazine hydrate. The films were prepared with one molar bath concentration and for various deposition times. The data showed that as-prepared and annealed thin films are polycrystalline with cubic structure and predominantly textured along 100. Results showed that thinner films are more prone to post deposition heat treatments as compared to thicker ones. Deposition parameters and thermal treatment strongly influence the optical properties of PbS films.
Laser Surface Alloying of Ni-Co Electroplated Low Carbon Steel
Authors: Hussain A. , Akhter R. , Farooq W.A. , Aslam M.
Published: June 2010

Laser surface alloying of Ni-Co electroplated steel using 900 W CW CO2 laser to develop Fe-Ni-Co alloy on the surface is reported. Fe-Ni-Co alloys of different compositions are produced by varying the working speed from 0.25 m/min to 3m/min and laser spot size from 0.6 mm to 5mm. The development of microstructure in the melted zone is analysed in terms of composition variation and cooling rate. The microhardness of newly formed alloys reported here are three times higher as compared to base metal. Martensite is observed in the laser modified zone.
Effect of Deposition Parameters and Annealing on the Morphology and Optical Properties of Pbs Thin Films
Authors: Zaman S. , Asim M.M. , Siddique S. , Mahmood S.K.
Published: June 2010

Polycrystalline PbS thin films are being potentially used in different optical applications. Optimization of their optical response is always an area of interest. In the current paper, we report on the effect of deposition parameters such as concentration of reactants, dipping time and post deposition heat treatment on the grain size, structure, resistivity and optical response. Spontaneous reaction of lead acetate and thiourea in aqueous hydrazine hydrate was used for depositing PbS thin films on glass substrates. The deposition temperature was kept close to 100°C. Deposition of PbS films at such a high temperature and strong reactant concentrations has not been much emphasized in literature. The characterization of physical and optical properties was done by using XRD, SEM, DSC, dual beam spectrophotometer and two probe methods for resistivity measurement. Mean grain size and surface disorder increased with increasing reactant concentrations and dipping time. However, the effect was less prominent with increasing concentration of reactants than the deposition time. The structural features such as crystallite size, structure and film thickness directly correspond to photosensitivity and optical properties of thin films. Annealing affected the electronic properties considerably and lowered the band gap of material but did not cause any appreciable change in structure except smoothening of the grain boundaries to certain extent.
Effect of Zr Addition on the Mechanical Behavior, Ductility and Wear Resistance of Aluminum Grain Refined by Titanium
Authors: Zaid A.I.O. , Al-Qawabah S.M.A.
Published: June 2010

Aluminum and its alloys are the second most commonly used metal for a variety of engineering applications. They solidify in columnar structure with large grain size which normally affects their mechanical behavior and surface quality. It is now becoming customary in aluminum foundry to grain refine their structure by adding either titanium or titanium + boron to their melt before solidification. In this paper, the effect of addition of Ti on the mechanical properties, ductility and wear resistance of commercially pure aluminum is investigated. Titanium was added at a level of 0.15 % wt. This ratio corresponds to the peritictic limit on the Al-Ti phase diagram and is normally used for grain refining of aluminum. It was found that addition of Ti at this level resulted in grain refinement of aluminum structure whereas addition of Zr alone resulted in grain coarsening of Al structure while it resulted in grain refinement when it is added in the presence of Ti. Regarding the effect of Zr on the wear resistance of aluminum it was found that at small loads and speeds addition of Ti or Zr or both together resulted in deterioration of its wear resistance whereas at higher loads and speeds resulted in pronounced improvement of its wear resistance.
Ultrasonic Surface Mechanical Attrition of Commercially Pure Ti to Induce Nanocrystalline Surface Layer
Authors: Mansoor M. , Lu J.
Published: June 2010

In the domain of incremental nanotechnology, surface mechanical attrition treatment is a technique which can transform superficial structure of a material to nanocrystalline without changing the chemical composition. This study is a part of the development and implementation of the technique by using ultrasonic vibrations. The material used is pure titanium in rolled and annealed condition. The nanocrystalline structure is characterized using X-ray diffraction (XRD), and transmission electron microscopy (TEM). The measured grain size is in the order of 5~60 nm. A correlation in the results of XRD and TEM is also discussed.
Impact of Metal-Organic Interface on the Growth Mechanism and Magnetic Properties of Permalloy (Fe : Ni) Films Sputtered on Self-Assembled Monolayers of Polar and Nonpolar Molecules
Authors: Ahmad S.N. , Strouse G.F. , Shaheen S.A.
Published: June 2010

Metal deposition on self-assembled monolayers (SAMs) with different terminal organic functional groups is a growing area of research and the metal-organic interface has been extensively studied in the past two decades. Apart from impacting existing technologies, it may have a profound impact on the emerging future technologies such as molecular electronics. The morphology of the deposited metals is strongly influenced by the nature of the chemical interactions occurring at the interface of the organic functional group (OFG) of the SAM and the deposited metal. Our interest for such studies stems from different perspective, as we are interested in determining the impact of the interface on the morphology and hence the magnetic properties of the deposited magnetic materials. We have sputtered a magnetic material, permalloy (Ni79Fe21), on self-assembled monolayers of polar and nonpolar molecules, and have observed contrasting magnetic behaviors of permalloy on these surfaces. We have observed the formation of uniform film on polar regions and cluster are formed on nonpolar regions. Further investigations reveal that the cluster formation gives rise to superparamagnetism, while the uniform film shows a usual ferromagnetic behavior. The observed contrast in morphology and magnetism of Py is attributed to different growth mechanisms arising from difference in polarity of the SAM surfaces.
Estimation of the Hardness for Laser Surface Hardening of Plain Carbon Steel
Authors: Ashraf M.M. , Hussain A. , Akhter R. , Farooq W.A. , Aslam M.
Published: June 2010

Laser surface hardening of plain carbon steel is simulated and software in Mathematica has been developed. The software estimates the hardness of plain carbon steel under different carbon contents and processing speeds. The flow chart explains the algorithm of the software. Our results show that hardness increases with carbon contents. The hardness increases slightly with processing speed but at the cost of decrease in hardened depth. The results for test material coincide with the experimental values from independent research results.
The Influence of Si Additive on Structural and Microstructural Properties of Cu-Zn Ferrite System
Authors: Uzma Ghazanfar , Abbas G.
Published: June 2010

Mixed Cu-Zn ferrites (for x = 0.66 to 0.99) are prepared by the double sintering ceramic method. Locally available low cost Fe2O3 with 0.5wt% of Si additive is used for this purpose which reduced the process price markedly and improves the properties of the ferrite produced. The chemical phase analysis carried out by X-ray powder diffraction method confirms the major phase of Cu-Zn ferrite structure. Lattice parameters, X-ray density and mass density along with porosity have been investigated to study the effect of composition. Lattice parameters shows a decreasing trend with increasing Cu content, x. whereas, both X-ray density and mass density increases with increasing x, which in turn decreases the porosity due to successive presence of Si in Fe2O3. This decrease in porosity along with chemical homogeneities, distribution of phases and grain formation were also observed from Scanning electron micrographs at different magnifications.
Tuning of Gadolinium Based Compounds for Potential Application in Self-Controlled Hyperthermia Treatment of Cancer
Authors: Ahmad S.N. , Shaheen S.A.
Published: June 2010

We report on the synthesis and investigation of magnetic properties of several new Gd based alloys suitable for their potential use in self-controlled hyperthermia treatment of cancer. Self-controlled hyperthermia is a non-invasive technique that employs heating of magnetic materials (ferromagnetic bulk sized thermo-seeds or magnetic nanoparticles) in a. c. fields to cure cancer cells. Magnetic materials with Curie temperature (Tc) in the range of 40-46oC are desired, as decreased magnetic coupling in paramagnetic regime (above Tc) provides a safeguard against overheating of normal cells. The need for developing such materials was dictated by the lack of existing magnetic materials with magnetic ordering temperature in the suitable range of hyperthermia applications. This study shows that these materials have high magnetization values and their Tc values can be varied linearly over a broad range by adjusting the composition of the constituent elements.
Microstructural and Electrochemical Characterization of Ni/Ti2N Composite Coating for Sintered NdFeB Permanent Magnets
Authors: Ali A. , Ahmad A. , Deen K.M. , Ahmad R.
Published: June 2010

Sintered NdFeB magnets have complex microstructure that makes them susceptible to corrosion in humid or moist environments. The paper presents the anticorrosion characteristics of a novel Ni/Ti2N composite coating applied through electrodeposition and cathodic arc physical vapour deposition (CAPVD) to sintered NdFeB permanent magnets. The performance of composite coating was evaluated in simulated marine environment with the help of dc polarization techniques. The rate of coating degradation was also determined by employing ac electrochemical impedance spectroscopy (EIS). The coating morphology and surface chemistry were studied with scanning electron microscope (SEM). X-ray diffraction (XRD) was used for identification of component phases in the coating-substrate system. The results showed that the composite coating provided an adequately improved corrosion protection to the sintered NdFeB magnets in the simulated marine environment compared to the earlier reported ceramic and metallic coatings. The composite coating did not damage the magnetic properties of coating-substrate system that remained at par with the ceramic and nickel coating having copper interlayer.
Diffusion Bonding of Austenitic Stainless Steel 316L to a Magnesium Alloy
Authors: Elthalabawy W. , Khan T.I.
Published: June 2010

Dissimilar metal combinations are often necessary when manufacturing a component in order to meet particular functional and engineering requirements or protect against environmental degradation. Stainless steels are used in a diverse range of applications due to their excellent corrosion resistance, formability and strength. The 316L stainless steel also shows good crashworthiness due to its high strain rate sensitivity which makes it suitable for the transportation industry. The joining together of the 316L steel and AZ31 magnesium alloy cannot be achieved using conventional fusion welding methods and therefore, diffusion bonding using interlayers was used to overcome the differences in their physical properties. The results show that Cu and Ni interlayers form a eutectic with the magnesium which enhances wettability and bond formation through isothermal solidification. The effect of hold time on the microstructural developments across the joint region was studied at a bonding temperature of 530oC and 510oC for the Cu and Ni interlayers respectively using a bonding pressure of 0.2 MPa. This preliminary investigation shows that by increasing the bonding time from 5 to 60 minutes results in a Cu-Mg and Ni-Mg eutectic phase structure forming along the bond interface. By holding the joint at the bonding temperature for 15 minutes initiates isothermal solidification of the joint and this was confirmed by DSC analysis. However, the movement of the solid/liquid interface on solidification pushes intermetallic phases into the center of the bond during the solidification stage. The intermetallics increase the hardness value of the bond interface and lower final bond strengths.
Fatigue Crack Growth Behavior in a Rolled Plate of Aluminum Alloy
Authors: Ejaz N. , Muhammad W. , Salam I.
Published: June 2010

Aluminum alloys generally contain constituent particles. The population density and size these particles are important while considering fatigue performance. In present study, the crack growth process in stage II in the rolled plate of a high strength aluminum alloy AA 2219 was studied on samples prepared along the rolling direction. A three fold approach was adopted to understand the fatigue crack growth process: i) microstructural analysis ii) fatigue testing iii) post-fracture analysis. Microstructural analysis revealed a high density of constituent particles in the material. EDS analysis showed that the particles were mainly of CuAl2 type. However, particles with high concentration of Fe and Mn were also present in the material. Fatigue crack propagation tests were performed by using middle tension (MT) specimens prepared in rolling direction under constant amplitude loads. The da/dN vs ΔK plot on log-log scale showed a sigmoidal shape with a sharp increase of crack growth rate in the steady state regime.
Topographical features were studied to understand the interaction of fatigue crack with the microstructural features. Post fracture analysis revealed that the macro fracture appearance changed with the change of stress level. However, the general mechanism of crack growth, in all the stress levels studied, was by formation of striations. At lower stress levels almost flat region with striations is present upto the final fracture. The crack growth surface showed crystallographic features with crack propagation almost perpendicular to the loading direction. However, a comparatively tortuous fatigue region was evident in the sample tested at high level of stress. The observation of crack path surface at high magnification did not reveal any influence of particles on the crack growth process. However, in sections taken from the fractured samples cracking and debonding of the constituent particles was observed near the fatigue crack path.
Effect of Cu on Structural and FF-Behavior of NiTi Shape Memory Alloy
Authors: Rani S. , Awan M.S. , Qureshi I.N. , Yasmin F. , Farooque M.
Published: June 2010

The functional fatigue behavior of Ti50Ni30Cu20 (at. %) shape memory alloy was investigated after subjecting to cold working and heat-treatment. Copper addition modified the phase transformation behavior with the introduction of B19-phase in the binary NiTi alloy. It was observed that aging after annealing and thermal cycling (-60 to 100)°C significantly effect the transformation temperatures. Observations in optical microscope and scanning electron microscope reveal inhomogeneity in the composition in the form of coarse Cu+Ti-rich precipitates. Investigations under transmission electron microscope showed growth of internally twined martensitic plates in solution treated sample. The phase transformation temperatures were determined with differential scanning calorimeter. The transformation temperatures were shifted towards lower side. Dislocations introduced during cold working and fine precipitation after aging, may be responsible for this change in the transformation characteristics of the material.
A Novel Fabrication Method for Nitinol Shape Memory Alloys
Authors: Rizvi S.A. , Khan T.I.
Published: June 2010

Nitinol (NiTi) shape memory alloys are widely used in a variety of biomedical applications, such as dental implants, cervical and lumbar vertebral replacements, joint replacements and stents. In this study, commercially pure Ti and Ni foils ~100 um thick were diffusion bonded in vacuum. The experimental conditions were optimized to achieve a near equiatomic composition to produce NiTi SMA thin foil of approx. 5-8 micron thick. The cross-sectional surfaces of joint were subjected to metallographic investigation using optical microscope after grinding, polishing and etching. Scanning electron microscope equipped with EDX system was utilized to characterize the bonded layer and compositional analysis. Differential scanning calorimetry (DSC) technique was employed to determine the shape memory effect. The samples were subjected to X-ray diffraction analysis in order to establish phase structures formed during the diffusion bonding stage. An ultra fast femto-second laser facility was utilized to ensure the production of complex shapes or patterns within micron scale.
Evaluation of Phase Transformation in Manganese Steels by Eddy Current Method
Authors: Khan S.H. , Khan Aamer Nusair , Mahmood K.
Published: June 2010

An investigation was conducted to explore the applicability of eddy current nondestructive evaluation technique for the characterization of manganese steels. Specimens of two different types of manganese steels were subjected to various compression loads. The specimens were then evaluated by mechanical and eddy current testing. The hardness and eddy current values were increased due to conversion of austenite to martensite. In this study the correlation between eddy current parameters and compression load was discussed.
The Effect of Sn on the Impedance Behaviour of Al-Zn Alloys in Natural Chloride Solution
Authors: Isa M.C. , Ahmad M.Y. , Daud Abdul Razak , Daud M.
Published: June 2010

Electrochemical behaviour of cast Al-Zn alloys in natural chloride solution were investigated by potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). Results from open circuit potential (OCP) measurement against immersion time showed a stable free corrosion process was achieved after 15 kiloseconds and alloys with more Sn contents had shifted OCP value towards more negative direction. Potentiodynamic polarisation curves showed that the corrosion potential (Ecorr) of aluminium alloys with Sn addition were much active compared to alloy without Sn. The anodic curves were characterized by no sign of passive current due active dissolution on the surface of the Al-Zn-Sn alloy. SEM images show that the presence of Sn in Al-Zn alloys produces better and uniform dissolution morphology. EIS results confirm that the presence of Sn is beneficial in improving anodic dissolution of Al-Zn alloys by reducing resistance to polarization (Rp). The presence of 0.1%wt. Sn in Al-Zn alloy has been found to be useful in activating electrochemical reaction at alloy-solution interface based on inductive loop in EIS diagram.
Effect of the Fillers Contents on the Chemical, Mechanical and Thermal Properties of Polymer Composites
Authors: Quddos A. , Hussain S.M. , Hafiz-ur-Rehman  , Abbas T.
Published: June 2010

Polymer composites are used in numerous applications. In spite of this fact, new developments are still under way to explore in other field of application of these materials and to tailor their properties for more extreme condition. A particular emphasis is focused on fillers content is summarized. Some steps towards the functionally graded materials are illustrated. The FT-IR spectroscopic studies revealed the information about curing of epoxy with fillers. It was observed that mechanical properties like tensile strength, hardness etc get enhanced up with filler contents. The effect of the different formulations were investigated and discussed for optimum process condition.
Thermal and Electrical Conductivities of Carbon Fibers and Carbon Nanotubes Incorporated Polyurethanes Composites
Authors: Abdullah Shahrul A. , Frormann Lars , Saleem Anjum
Published: June 2010

Single filler polyurethane composites with carbon fibers (CFs) and multi-walled carbon nanotubes (MWNTs) were prepared by melt mixing methods and its thermal as well as electrical resistivity characteristics were investigated. The influences of fillers and mixing methods on thermal and electrical conductivity of CF/- and MWNT/polyurethane composites were investigated and the result shows that the addition of carbon fillers improved the thermal conductivity of the polyurethane composites. Higher filler concentration results in better thermal conductivity because better formation of thermally conductive networks along polymer matrix to ensure the thermal was conducted through the matrix and the network along the polymer composites. The presence of carbon additives improves the electrical resistivity of the materials as well. The present study revealed the potential of carbon as agent for better thermal and electrical conductivities and their properties depend strongly on the dispersion and distribution of the fillers in the polymer matrix.
Investigation of Electrical Properties of Polyaniline Nanocomposites by Impedance Spectroscopy
Authors: Afzal A.B. , Akhtar M. Javed , Nadeem M. , Masood-ul Hassan M.
Published: June 2010

Polyaniline (PANI) nanocomposites were synthesized by incorporating separately synthesized metal nanoparticles in 1-methyl-2-pyrrolidinone (NMP) solution of polyaniline. PANI was prepared by oxidative reduction of aniline using chemical method. Silver nanoparticles were produced by inert gas condensation; whereas gold nanoparticles were synthesized by the reduction of gold salt. FTIR confirmed the formation of PANI in all samples. The electrical properties of the nanocomposites were determined by impedance spectroscopy. The conductivity relaxation analysis suggested microphase separation of NMP plasticized films into phases of reduced and oxidized repeat units. The conductivity of PANI films increases with the increase in concentration of embedded nanoparticles. Incorporation of metal nanoparticles in PANI causes considerable decrease in the real part of impedance.
Deposition and Characterization of CdSe Nanoparticles in Polymeric Materials
Authors: Quddos A. , Khan Mohammad Bilal , Wadood A. , Malik M.A. , O’Brien Paul
Published: June 2010

Cadmium selenide nanoparticles coated with zinc sulphide CdSe/ZnS were prepared using dual source method. The composites were fabricated by stabilizing chemically synthesized semiconductor CdSe/ZnS into Laurylmethacrylate (LMA) and ethyleneglycol dimethacrylate (EGDMA) matrices in the presence of tri-n-octylphosphine (TOP). CdSe/ZnS were dispersed in toluene as a compatible medium for the polymerization and cross-linking of poly Laurylmethacrylate (LMA) networks. Transparent, fluorescent and flexible nano composites (NCs) materials resulted. The nano size particles and polymer composites were characterized by XRD, TG-DTA, IR, TEM and SEM.
Charge Transport Mechanism and the Effects of Device Temperature on Electrical Parameters of Au/ZnPc/N-Si Structures
Authors: Hussain A. , Akhter P. , Bhatti A.S.
Published: June 2010

Gold/Zinc Phthalocyanine/n-Si metal semiconductor contact with organic interfacial layer have been developed and characterized by Current–Voltage-Temperature (I-V-T) measurements, to study its junction and charge transport properties. The junction parameters, of diode ideality factor (n), barrier height (b) and series resistance (R¬S), of the device are found to shift with device temperature. The barrier height and the diode ideality factor are found to increase and the series resistance is found to decrease with increasing device temperature. The activation energy of the charge carriers is found to be 44 meV and the peak of interface state energy distribution curves is found to shift in terms of Ess-Ev value from 0.582 eV to 0.776 eV with increasing device temperature. The data analysis implies that the Fermi level of the organic interfacial layer shifts as function of device temperature by 100 meV in the device temperature range of 283K to 343K. In terms of dominant conduction mechanism, the I-V-T data analysis confirms the fit of data to the relationship log (IV4)  V1/2 for higher device temperatures and the Poole-Frenkel type is found to be the dominant conduction mechanism for the hybrid device.
DLTS Studies of Al Diffused n-Si
Authors: Siddique S. , Asim M.M. , Saleemi F. , Naseem S.
Published: June 2010

We have studied the electrical properties of Si p-n junction diodes by deep level transient spectroscopy (DLTS) measurements. The p-n junctions were developed on a Phosphorus doped Si by depositing Al and annealing at various temperatures. In order to confirm junction formation, current-voltage and capacitance-voltage measurements were made. Two deep levels at Ec-0.17 eV (E1) and Ec-0.44 eV (E2) were observed in the DLTS spectrum. These traps have been characterized by their capture cross-section, activation energy level and trap density. On the basis of these parameters, level E1 can be assigned as V-O complex and E2 as P-V complex. These traps are related to the growth of n-Si wafer and not due to Al diffusion.
Processing, Characterization and Properties of Specially Constituted Zr-Based Bulk Amorphous Alloys
Authors: Iqbal Muhammad , Akhter J.I.
Published: June 2010

Bulk metallic glasses (BMGs) are an emerging class of materials. The amorphous alloys have very attractive properties. There is potential for applications. The quaternary and pentanery (ZrCuAlNi)100-xTix (x = 0, 2 and 5 at. %) alloys were synthesized by melting 2-3N pure metals in an arc furnace. Amorphous ingots were produced using Cu mold casting technique. The alloys showed wide supercooled liquid region Tx, high thermal stability and good glass-forming ability (GFA). Many thermal parameters like Trg, , , β and  were measured employing high temperature differential scanning calorimetry (DSC). Structural characterization was carried out by X-ray diffraction (XRD) technique. Microstructural characterization was conducted using high resolution field emission scanning electron microscopy (FESEM) and elemental analysis was done using energy dispersive spectroscopy (EDS). Crystallization behavior and phase formation was studied. Activation energy for crystallization was calculated using Kissinger and Ozawa equations. The alloys show double stage crystallization. Mechanical properties were measured. Compression test was carried out and fracture strength and strain were determined. The fracture behavior was studied which showed veins like patterns, shear bands formation and liquid droplets.
Influence of Atmospheric Annealing on the Conductivity of Mn-Doped PZT Ceramics
Authors: Shuaib M. , Hall D.A.
Published: June 2010

Conductivity measurements were carried out on Mn-doped PZT ceramics in order to investigate the changes in defect chemistry with annealing, by identifying the charge carriers such as lead or oxygen vacancies. PZT compositions were prepared by sol-gel method in rhombohedral region Pb(Zr0.56 Ti0.44)O3 with Mn contents 0.4, 0.8, 1.5 and 2 wt.%. Nano-sized powder (~21nm) was obtained after calcination and bulk density values of >98% were achieved upon sintering. It was found that nitrogen annealing reduced the electrical conductivity strongly as compared to oxygen and air annealing and the possible charge carriers were single ionised oxygen vacancies along with and vacancies.
Crack Bridging in Stress Corrosion Cracking of Duplex Stainless Steels
Authors: Sarwar M. , Ahmad E. , Manzoor T.
Published: June 2010

Wedge open loaded (WOL) specimens of age hardened Zeron 100 duplex stainless steel were tested in 3.5 wt % NaCl solution with cathodic polarizes applied at-900mV/SCE to investigate stress corrosion cracking mechanism in duplex stainless steel. The interaction between microstructure and mechanism of stress corrosion cracking was studied. Fracture mechanism was studied by using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The material was found cracked by ferrite cleavage, austenite tearing and austenite dissolution by environment. The ferrite cleavage took place along {100} planes and {112} twin habit planes. The austenite grains appear to act as crack bridging & crack arrester and failed by tearing & stress corrosion cracking.
Software Development for Shear Stress Distribution in Multicell Beams of Isotropic Materials
Authors: Tariq Muhammad Mushtaq , Ahmed Malik Nazir
Published: June 2010

Main purpose of this work is to present the constrained torsional loading of multicell beam of isotropic materials in a user friendly format, using the computer programming. This computer program has been written in Microsoft Visual Basic, and its source code consists of 593 lines. Distribution of Saint Venant shear stresses in multicell beam of isotropic material has been calculated. Importance of shear stress in processing of materials has been discussed. The design and development of this software has also been enlightened by providing Algorithm and flow chart in paper. Although this software is restricted to multicell beam of three cells, yet future versions can have ability to address more complicated shapes and cases of multicell beams. Software also describes nomenclature and mathematical formulas applied to help user understand the theoretical background. The geometry of multicell beam is defined for three cells. Four main sections of software are; input data, intermediate calculations, numerical results and graphical output. The results of this software have been verified using MATLAB. Different contour displays indicating magnitude and direction of stress and displacement are plotted in MATLAB for multicell beam of isotropic material. MSC Patran has also been utilized to get the results for multicell beam of isotropic materials for comparison and validation. Development and use of this software provides inspiration to highlight new areas of consideration and research.
Effect of Heat Sinks on Visco-Elastic & Mechanical Properties of EPDM Based Ablative Composites
Authors: Bashir M.A. , Ahmad H. , Ahmed R. , Alvi R.A. , Khan Mohammad Bilal
Published: June 2010

Ablative composites are heat shielding, protective materials that are being used in aerospace industry to protect inner hardware and sensitive devices. The aero dynamic vehicles have to face high stresses, ultra high temperature and adverse conditions of air friction. It is required to develop the materials with light weight and high modulus. EPDM, being heat and ozone attack resistant is the best candidate for the preparation of ablative composites by introducing different heat sinks such as silica, glass fiber, carbon fiber, asbestos, carbon and their combinations have been studied in this work. The prepared materials were tested and it was found that visco elastic behavior of the composites affected by the addition of reinforcing filler (carbon, silica), semi-reinforcing filler (carbon fiber, glass fiber) and non-reinforcing filler (asbestos powder). Mechanical properties tested at different rates, revealed the improvement in tensile strength and % elongation in case of reinforcing and semi-reinforcing fillers but showed adverse effect in case of non-reinforcing fillers. Rheological investigations of these novel composites shows that moony viscosity of the materials containing glass fiber, carbon fiber, silica decreases in the order glass fiber > carbon fiber > silica.
Transient Liquid Phase Bonding of High Strength Low Alloy Steel Coiled Tubing
Authors: Javadzadeh A. , Khan T.I.
Published: June 2010

The oil and gas industry of Alberta, Canada use coiled tubing made from high strength low alloyed steel (HSLA) to extract oil from reservoirs deep beneath the earth’s surface. The repeated use of the coiled tubing in down-hole wells results in fatigue failure of the tube material. In order to repair the coiled tube, a section of tubing is fusion welded using tungsten inert gas welding onto the remaining tube steel. However, the fusion weld often fails within the weld region and therefore, alternative joining methods need to be explored to minimize detrimental changes at the joint region. In this study transient liquid phase (TLP) bonding is used with the aid of metal interlayers based on the Ag-Cu and Ni-P systems. These interlayers form a liquid at the melting point and the gradual diffusion of alloying elements into the joint and the diffusion of elements out of the joint region induces isothermal solidification whilst the joint is held at the bonding temperature. The TLP bonding behaviour of the HSLA steel as a function of bonding parameters was investigated and the quality of the joint region determined using metallurgical techniques (light and scanning electron microscopy, energy dispersive spectroscopy) and mechanical testing.
Microstructural Characterization of Silicon Added Titanium Aluminide
Authors: Khan Aamer Nusair
Published: June 2010

Titanium aluminides intermetallic compounds have received great attention during the past decade, since they have the potential, in aircraft and automotive engines, to replace the high density Ni-base superalloys However, these intermetallics possess poor oxidation properties at high temperatures. Previous studies showed that protective alumina scale formation on γ-TiAl can be obtained by small additions (around 2 at.%) of Ag. In the present study, a number of cast Ti–Al–Si alloys were investigated in relation to transient oxide formation in air at 1300°C. After various oxidation times the oxide composition, microstructure and morphology were studied by combining a number of analysis techniques. The TiAl–Si alloys appear to form Al Ti and Si oxides. However, the formation of silicon oxide at the interface of base metal and scale slows down the oxidation rate significantly.
Role of Combustion Energy in Laser Cutting of Austenitic Stainless Steel
Authors: Rauf A. , Hussain A. , Akhter R. , Farooq W.A. , Aslam M.
Published: June 2010

Cutting of austenitic stainless steel of 0.5mm and 2mm thickness with CO2 laser has been carried out using oxygen, nitrogen and compressed air as assist gases. It has been observed that when oxygen is used as assist gas, the contribution of combustion energy was found to be 60 to 80 % more as compared to the other two types of assist gases. The cutting speed for 0.5 mm sheet was about 11 times where as for 2 mm stainless steel it was around 16 times. The role of combustion energy were theoretically calculated and compared with experimental results and found to be in good agreement.
To Study the Mechanical Properties of Unidirectionally and Cross Rolled Ni-Cu Alloy Produced in VIM
Authors: Afzal M. , Ajmal M. , Butt T.Z.
Published: June 2010

Ni-Cu alloy was developed by melting in a vacuum induction furnace using pure elements i.e., Ni, Cu, Fe, Si, Mn and Cr. Four heats of approximately 4 kg each were prepared. All the heats have been casted in an ingot of 10 cm long and 5 cm in diameter in vacuum. These ingots were hot forged at a temperature of 900°C to break down the cast dendritic structure. All forged plates were cut into two halve. One half was rolled in unidirectional while other was rolled in multiple directions (cross rolling). During rolling after every 25 % reduction, the cold rolled samples were annealed at a temperature of 900°C for one hour. Each plate was cold rolled to a final thickness of 0.345 mm. Half of these rolled plate produced either by cross rolling or unidirectional rolling were annealed at 900°C for 20 minutes. The mechanical properties of each rolled plate in cold reduction and in annealed were also measured.
Unidirectional rolling and cross rolling has almost similar mechanical properties. The annealing of cross rolled and unidirectional rolling drastically reduced the yield strength. It was observed that the Ni-Cu alloy produced has slightly lower yield and ultimate tensile strength compared to the values reported in standards of Monel-400. However, it is within the acceptable range to be used for the various applications.
Deformation Behavior of Ultra-Thin Metal Foils in Strip Drawing Friction Test
Authors: Shimizu Tetsuhide , Manabe Kenichi , Yang Ming
Published: June 2010

This study focuses on the surface deformation of thin metal foils caused by friction. To clarify the effect of the relative ratio of surface plastic region to the foil thickness on global deformation behavior, strip drawing tests for ultra thin metal foil with 20μm and 100μm thickness were conducted As a result, different surface deformation and elongation behavior under the same friction condition were observed in different thicknesses. Aided by finite element analysis of the friction test, the contribution of the deformation caused by friction to the foil elongation was investigated and the importance of the friction on material deformation in metal foil forming was demonstrated.
Analyzing of Stainless Elliptical Cup Drawing Process
Authors: Huang You Min , Tsai Yi Wei
Published: June 2010

A methodology of formulating an incremental elasto-plastic three-dimensional finite element model, which is based on Prandtl-Reuss flow rule and von Mises’s yield criterion respectively, associated with an updated Lagrangian formulation, is developed to simulate elliptical cup drawing process. An extended algorithm is proposed to formulate the boundary conditions, such as the yield of element, maximum allowable strain increment, maximum allowable rotation increment, maximum allowable equivalent stress increment, and tolerance for nodes getting out of contact with tool. In order to verify the reliability and accuracy of the FEM code, the fractured thickness of a specimen in the simple tension test is adopted as the fracture criterion of forming limit in simulation. A set of tools was designed to perform the elliptical cup drawing experiment on the hydraulic forming machine. According to the simulation and experimental results, the limit drawing ratio (LDR) amounts to about 2.136 for penetration in the elliptical cup drawing process of this study. This paper also found a comparison of the LDR of different tool radii. According to the definition of LDR, when the die radius is increased from R3.0mm to R9.0mm, the LDR would increase from 2.11 to 2.157. When the punch radius is increased from r3.0mm to r9.0mm, the LDR would increase from 2.07 to 2.181. This paper has provided a better understanding of the elliptical cup drawing process for improving the manufacturing processes and the design of tools.
Roll Casting of Three Layers Clad Strip
Authors: Nakamura Ryoji , Sawai Masakazu , Nakamura Ryoji , Yamabayashi Takanori , Kumai Shinji , Watari Hisaki
Published: June 2010

A roll caster, which could cast the three layers of clad strip directly from the molten metal, was designed, assembled and tested. The base strip was AA3003 aluminum alloy and overlay strips were AA4045 aluminum alloy. An unequal diameter twin roll caster was modified to cast clad strip. Two small rolls were amounted on a large roll. A scraper plate was used to prevent the mixture of the different kinds of melts. The casting of three strips and the connecting of strips could be operated by one roll caster. The interfaces between the strips were clear, and the mixture of the melt did not occur. The clad strip could be cold rolled without the annealing. The clad strip did not peel at connecting surface by the cold rolling and continuous bending. The strips were connected strictly. The casting speed was 20m/min, and this speed was much higher than the casting speed of the conventional twin roll caster for aluminum alloys.
Application of Back-Up Ring in Fine-Blanking Process
Authors: Yiemchaiyaphum Suthep , Jin Masahiko , Thipprakmas Sutasn
Published: June 2010

Considering the advantages of the fine-blanking process, the smooth-cut surface without further operation could be fabricated. However, one of the major problems of the fine-blanking is the occurrence of the die-roll formation. This problem is the main factor which affects the quality of the fine-blanked parts. In this study, to reduce the amount of die-roll formation, the application of back-up ring was proposed. The finite element method (FEM) was used to investigate the effects of back-up ring. In addition, the effects of bridge width were also investigated. The FEM simulation results illustrated that the mechanism of back-up ring and the effects of bridge width could be theoretically clarified base on the material flow analysis. The FEM simulation and experimental results showed the good agreement with each other. Therefore, the application of back-up ring could reduce the amount of die-roll formation on the fine-blanked parts. In this study, the amount of die-roll formation increased as the bridge width increase and it was constant at the bridge width of over 15 mm.