bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of Superparamagnetic Magnesium Ferrite Nanoparticles by Microwave-Hydrothermal Method
Authors: Verma Seema , Potdar Hari S. , Date Sadgopal K. , Joy Pattayil A. 
Published: April 2011

AbstractSuperparamagnetic magnesium ferrite, MgFe2O4, nanoparticles were synthesized under mild microwave hydrothermal (MH) conditions. Transmission electron microscopic studies showed that the average particle size of the ferrite obtained is ∼3 nm, with a narrow size distribution. Temperature dependent AC magnetic susceptibility measurements at 2 Oe showed characteristic feature of superparamagnetism with blocking temperature, TB, at 47 K. TB decreases with increasing DC magnetic field as evidenced by zero-field-cooled susceptibility studies at 50 and 500 Oe (TB = 38 and 27 K respectively). As a typical superparamagnetic behavior, the zero-field- cooled and the field-cooled magnetizations diverge below TB. Magnetic hysteresis behavior is observed below TB, with a high coercivity of 185 Oe at 12 K, and magnetic hysteresis behavior disappears when measured above TB. The results indicate that MH method is highly suitable for the synthesis of superparamagnetic ferrite nanoparticles of uniform size distribution.
Growth and Characterization of ZnO Nano-Rods on Si Substrate by Pulsed Laser Ablation
Authors: Gupta Vinay , Bhattacharya P. , Yuzyuk Yu. I. , Katiyar R.S. 
Published: April 2011

AbstractZinc oxide (ZnO) nanorods were fabricated directly on silicon substrate with diameters in the range of 70-350 nm and up to 15 νm long using pulsed-laser deposition at a relatively low processing temperature (450°C) without any catalytic template. The influences of substrate temperatures and the oxygen pressures on the formation of ZnO nanorods were investigated. The Raman scattering studies and scanning electron microscopy results indicated that the ZnO nanorods were well aligned along c-axis and isolated from each other. The additional Raman modes at ∼ 477 cm−1 and 574 cm−1 were observed in the c-axis oriented ZnO nanorods which attributed to the activation of the upper and lower surface phonon modes respectively.
On the Role of Grain-Boundary Films in Optimizing the Mechanical Properties of Silicon Carbide Ceramics
Authors: Ritchie R. O. , Zhang X.-F. , De Jonghe L. C. 
Published: April 2011

AbstractThrough control of the grain-boundary structure, principally in the nature of the nanoscale intergranular films, a silicon carbide with a fracture toughness as high as 9.1 MPa.m1/2 has been developed by hot pressing β-SiC powder with aluminum, boron, and carbon additions (ABC-SiC). Central in this material development has been systematic transmission electron microscopy (TEM) and mechanical characterizations. In particular, atomic-resolution electron microscopy and nanoprobe composition quantification were combined in analyzing grain boundary structure and nanoscale structural features. Elongated SiC grains with 1 nm-wide amorphous intergranular films were believed to be responsible for the in situ toughening of this material, specifically by mechanisms of crack deflection and grain bridging. Two methods were found to be effective in modifying microstructure and optimizing mechanical performance. First, prescribed post-annealing treatments at temperatures between 1100 and 1500°C were seen to cause full crystallization of the amorphous intergranular films and to introduce uniformly dispersed nanoprecipitates within SiC matrix grains; in addition, lattice diffusion of aluminum at elevated temperatures was seen to alter grain-boundary composition. Second, adjusting the nominal content of sintering additives was also observed to change the grain morphology, the grain-boundary structure, and the phase composition of the ABC-SiC. In this regard, the roles of individual additives in developing boundary microstructures were identified; this was demonstrated to be critical in optimizing the mechanical properties, including fracture toughness and fatigue resistance at ambient and elevated temperatures, flexural strength, wear resistance, and creep resistance.
Ion Channel Sensor on a Silicon Support
Authors: Goryll Michael , Wilk Seth , Laws Gerard M. , Goodnick Stephen M. , Thornton Trevor J. , Saraniti Marco , Tang John M. , Eisenberg Robert S. 
Published: April 2011

AbstractWe are building a biosensor based on ion channels inserted into lipid bilayers that are suspended across an aperture in silicon. The process flow only involves conventional optical lithography and deep Si reactive ion etching to create micromachined apertures in a silicon wafer. In order to provide surface properties for lipid bilayer attachment that are similar to those of the fluorocarbon films that are currently used, we coated the silicon surface with a fluoropolymer using plasma-assisted chemical vapor deposition. When compared with the surface treatment methods using self-assembled monolayers of fluorocarbon chemicals, this novel approach towards modifying the wettability of a silicon dioxide surface provides an easy and fast method for subsequent lipid bilayer formation. Current-Voltage measurements on OmpF ion channels incorporated into these membranes show the voltage dependent gating action expected from a working porin ion channel.
A study of the growth curves of C. xerosis and E. coli Bacteria in Mediums Containing Cobalt Ferrite Nanoparticles
Authors: Flores Marjorie , Colón Nanell , Rivera Omayra , Villalba Nicole , Baez Yahira , Quispitupa David , Avalos Javier , Perales Oscar 
Published: April 2011

AbstractPrevious publications demonstrated the sensibility of the bacteria, when these were reproduced in mediums that contain nanoparticles of luminescent silicon. The mentioned effect takes place in the development of a bacteriological sensor. The present investigation is centered on the study of the growth curves of E. coli and C. xerosis, but now in the presence of nanosize particles of Cobalt Ferrite (CoFe2O4) which were produced by the co-precipitation method in a watery phase. These nanoparticles present ferromagnetism characteristics (coercivity at room temperature among 600-5000 Oe for a size around 15-40nm). The experiment results evidence that the adaptation period of the bacteria, in contact with a stable suspension of nanoparticles of Ferrite, shows a growth curve of above the one obtained in absence of the nanoparticles (standard curve). The probable interaction of the electric polarity that these possess should be involved with the observed phenomena.
Optimization of mechanical properties of thin free-standing metal films for RF-MEMS
Authors: Toonder Jaap M.J. den , Dijken Auke R. van 
Published: April 2011

AbstractThe mechanical properties of the thin film materials used in RF-MEMS are crucial for the reliability and proper functioning of the devices. In this paper we study a large number of aluminum alloys as possible RF-MEMS thin film materials. The yield strength and creep properties are measured using nano-indentation. The results show that the mechanical properties of thin aluminum films can be improved substantially by alloying elements. Of the alloys studied in this paper, AlCuMgMn in particular seems quite promising as a thin film material for RF MEMS, having both high yield strength and little creep. Using X-ray diffraction and electron microscopy, the observed effects are partly explained.
Microstructural Design and Evaluation of Porcelain/Mullite/Alumina Layered Structure for Dental Application
Authors: Jang Hyung-Jun , Park Dong-Ho , Jung Yeon-Gil , Lee Hee-soo 
Published: April 2011

AbstractPorcelain (veneer layer)/alumina (core layer) is a typical dental crown structure. Due to its high incidence of failure, a new porcelain/mullite (buffer layer)/alumina trilayer structure is designed, fabricated, and evaluated. Alumina green bodies were prepared by gel-casting process, and then calcined at 900 and 1100°C to infiltrate mullite precursor slurry of silica-rich (Al2O3·2SiO2) composition into the bodies. Porosity in the bodies is not dependent on calcination temperature, resulting in a similar infiltration depth. Porcelain was coated on the alumina sintered at 1600°C with and without mullite buffer layer. There are no delamination or cracks observed after firing the layered materials. Rod type microstructure and continuous composition are indicated at the interface in the case of the layered structure with mullite buffer layer. To investigate the cracking resistance behavior for this new structure, Vickers indentation and Hertzian contact fatigue tests were conducted. Cracks do not penetrate the interface with mullite buffer layer into the porcelain, showing a reversal case for the layered structure without mullite buffer layer. The layered structure with mullite buffer layer shows higher critical load for fracture than that without mullite buffer layer. Fracture mode of the layered structures in cyclic fatigue shows a top layer (porcelain) fracture at relatively low load (P = 250 N) and higher cycles (n = 106), and a bottom layer (alumina) fracture at higher load (P = 300 N) and relatively low cycles (n = 105).
Low Coherence Interferometric Metrology for Ultra-thin MEMs Structures
Authors: Walecki Wojciech , Wei Frank , Van Phuc , Lai Kevin , Lee Tim , Souchkov Vitali , Lau SH , Koo Ann 
Published: April 2011

AbstractWe present application of low coherence interferometry to characterization of ultra-thin MEMs structures such as membranes in micro-machined devices.
From an Integrated Biochip Detection System to a Defensive Weapon Against the SARS-CoV Virus: OBMorph
Authors: Lee Chih-Kung , Lin Chi-Wan , Lin Shiming , Lee Adam Shih-Yuan , Wu Jiun-Yan , Lee Shu-Sheng , Hsiao Wen-Hsin , Chen Shih-Jui , Wang An-Bang 
Published: April 2011

AbstractIn this paper, an integrated multifunctional biochip detection system, which we call “OBMorph“, are presented. This unique system integrates several optoelectronic-based biological diagnostic tools such as an ellipsometer, a laser Doppler vibrometer/interferometer, a SPR (surface plasmon resonance) analyzer, an interference microscope, a photon tunneling microscope, an optical coherence tomography unit and a confocal scanning microscope. This OBMorph system, useful as a powerful optical metrology diagnostic tool, can be used at the beginning of sensor chip fabrication, on to signal detecting and monitoring, and to the final biological analysis. The principles and experimental results of this multifunctional biochip detection OBMorph system are presented.In addition, an innovative SARS (Severe Acute Respiratory Syndrome) virus denaturing chemical compound that was derived using the OBMorph system to study biolinker fabrication in biochips, are discussed. Several testing strategies are presented herein which proves the effectiveness of the new chemical compound, biochip technology in denaturing the SARS virus. Analysis under an atomic force microscope confirms the actual breaking down of the virus treated by the chemical compound. The fundamentals of how the chemical compound denatures the virus and renders it toxicity useless, is based on principles of nanotechnology and bio-mechanics. Results from preliminary studies show that this denaturing principle can be also effective against other deadly viruses and even bacteria. Some design strategies and innovative working mechanisms derived from study of this chemical compound which can denature the SARS-CoV, are also discussed.
Ab-initio Structural Properties and Stress-Deformation Analysis by Rheological Modeling of Diamonds-containing Nanocarbon nanotubes
Authors: Kireitseu Maksim V. , Bochkaryova Liya 
Published: April 2011

AbstractIn our laboratory, we developed a simple method for measuring the mechanical properties of single nanotubes and modeling its mechanical properties by rheological analysis. The technique involves depositing nanotubes from a suspension in a suitable liquid onto well- polished alumina ultrafiltration membranes with a pore size of about 200 nm. Rheological models of the composite systems have been proposed and confirmed by in-situ experiments at AFM indentation.
Namomechanical Imaging and Nanoscale Elastic Modulus Measurements of SnO2 Nanobelts
Authors: Zheng Y. , Geer R. E. 
Published: April 2011

AbstractThe relative surface contact stiffness of SnO2 nanobelts has been investigated via ultrasonic force microscopy (UFM). The nanobelt crystal structure, as determined via transmission electron microscopy, was indexed to the tetragonal rutile structure (with lattice constants identical to those of bulk SnO2) as reported previously. The atomic Sn:O composition of the nanobelts studied was at or near 1:2. Topographic imaging studies revealed the nanobelt surface to be atomically flat with the exception of surface nanodots, assumed to be local SnO2 crystallites. Preliminary reduced modulus measurements were carried out via differential UFM on both the flat and nanodot regions of the nanobelt. Using the underlying Si substrate as a calibration standard the SnO2 modulus was estimated at 157±12 GPa, significantly lower than corresponding bulk values for any of the observed crystal orientations. We speculate this discrepancy is due in part to a combination of the aspherical probe tip and unknown adhesive properties of nanobelt. An intrinsic reduction of the SnO2 nanobelt modulus cannot be ruled out.
Evaluation of Interface Strength between a Copper Submicron Dot and Silicondioxide Substrate
Authors: Hirakata Hiroyuki , Kitamura Takayuki , Yamamoto Yoshitake 
Published: April 2011

AbstractAn experimental evaluation method of interface strength between ductile submicron-dots and a hard substrate is developed. The validity is examined with copper (Cu) cylindrical dots of submicron scale on a silicondioxide (SiO2) substrate. A hard-layer of tungsten (W) is employed to restrain the deformation and concentrate the stress near the free-edge of Cu/SiO2. A diamond tip is dragged horizontally along the SiO2 surface and the load is applied to the side edge of the W layer at a constant displacement rate using a modified atomic force microscope. Both the lateral and the vertical loads and displacements are continuously monitored during the test. After the tip hits the W layer, the lateral load, Fl, increases almost proportionally with the lateral displacement, σl. The Cu dot with the W layer then is clearly separated from the SiO2 along the interface. The restraint by the W layer works well so that there are little damages in both the delaminated W/Cu dot and the substrate. The delamination lateral load, FlC, is successfully evaluated.
Synthesis and Study of Nanostructures Via Microwave Heating
Authors: Kharissova Oxana V. , Zavala Eder , Ortíz Ubaldo , Hernández-Piñero Jorge L. , Soloviev Stanislav 
Published: April 2011

AbstractThis work is devoted to microwave heating of graphite, sucrose, calcined sucrose, and a mixture of graphite with sucrose to produce carbon nanotubes (CNT's). The samples were submitted to microwave radiation (power 800W, frequency 2.45 GHz) in air and high vacuum (10−5Torr) for 30 – 60 min. The oven temperature was approximately 1200°C. After vaporization the condensed material was collected on various fused silica targets (different morphologies were used). The samples were found to contain a significant proportion of nanotubes, nanoparticles and fibers (1-2.8 micrometers), which appeared to be highly graphitized and helical structured. After deposition, the morphology of carbon nanotubes was studied with SEM, TEM and AFM techniques. It was observed that multi-walled nanotubes (MWNT's) were produced by this method. The morphology of fused silicon based substrates (SiO2, SiC) was studied as an important factor for the growth of carbon nanotubes. Many aspects as the size and shape of the obtained nanotubes on different substrates (porous and non-porous fused silicon substrates) were achieved, as well as the concentration of them across the substrate and other properties.
Effect of Substrate Bias on Structure and Properties of W incorporated Diamond-like Carbon Films
Authors: Wang Ai-Ying , Lee Kwang-Ryeol 
Published: April 2011

AbstractW incorporated diamond-like carbon (W-DLC) films were deposited on silicon (100) wafers by a hybrid deposition method combining ion beam deposition of carbon with DC magnetron sputtering of tungsten. During the films deposition, a wide range of negative bias voltage from 0 to -600 V was applied. W concentration in the film could be controlled by varying the Ar/C6H6 ratio in the supplying gas. In the present experimental condition, WC1−x nano-sized particles were not observed in the amorphous carbon matrix. Regardless of the W concentration in the film, it was found that the G-peak position of the Raman spectra had a lowest value at a bias voltage of - 200 V, which represents the highest sp3 bond fraction in the film. The highest residual stress, hardness and Young's modulus were also observed when the bias voltage was -200 V. This result shows that the mechanical properties of W-DLC films were mainly dependent on the atomic bond structure of carbon. On the other hand, the electrical resistivity significantly decreased by the W incorporation.
Characterization of Carbon Nanotubes/Cu Nanocomposites Processed by Using Nano-sized Cu Powders
Authors: Kim Kyung Tae , Lee Kyong Ho , Cha Seung Il , Mo Chan-Bin , Hong Soon Hyung 
Published: April 2011

AbstractCarbon nanotubes (CNTs) have attracted remarkable attention as reinforcement for composites owing to their outstanding properties1-3. CNT/Cu nanocomposites were fabricated by mixing the nano-sized Cu powders with multi-wall carbon nanotubes and followed by the spark plasma sintering process. The CNT/Cu nanocomposite fabricated from nano-sized Cu powders shows more homogeneous distribution of CNTs in matrix compared to that fabricated from macro-sized Cu powders. The hardness of CNT/Cu nanocomposite fabricated from nano-sized Cu powders increases with increasing the volume fraction of CNTs, while the hardness of that fabricated from macro-sized Cu powders decreases with the addition of CNTs.
A Molecular Dynamics Simulation Framework for an Al+Fe2O3 Reactive Metal Powder Mixture
Authors: Tomar Vikas , Zhou Min 
Published: April 2011

AbstractThis work focuses on the development of a classical molecular dynamics (MD) framework that can be used to analyze the quasi-static strength, elastic-constants, and dynamic strength of nanostructured Fe2O3+Al reactive metal powder (NRMP) mixtures. An interatomic potential is developed for the Fe2O3+Al NRMP system, accounting for the behavior of Al, Fe, Fe-Al intermetallics, Fe2O3, and Al2O3. This potential can be regarded as a generalization and combination of several existing potentials for the individual components in the system. The potential incorporates electronegativity equalization to account for pressure-induced phase transformation. In addition, the parameter set of the potential is capable of predicting the elastic properties of components over a range of 0 - 900 K.
Unconfined Twist: a Simple Method to Prepare Ultrafine Grained Metallic Materials
Authors: Zhao Yonghao , Liao Xiaozhou , Zhu Yuntian T. 
Published: April 2011

AbstractA new simple method – unconfined twist was employed to prepare ultrafine grained (UFG) Fe wire. A coarse grained (CG) Fe wire with a diameter of 0.85 mm was fixed at one end, and twisted at the other end. After maximum twist before fracture, in the cross-sectional plane, concentrically deformed layers with a width of several micrometers formed surrounding the center axis of the wire. The near-surface deformed layers consist of lamella grains with a width in submicrometer range. In the longitudinal plane, deformed bands (with a width of several micrometers) formed uniformly, which were composed of lamella crystallites (with a width in submicrometer range). The tensile yield strength and ultimate strength of the twisted Fe wire are increased by about 150 % and 100 % compared with the values of its CG counterpart.
The Role Of Vorticity In The Formation Of Tribomaterial During Sliding
Authors: Subramanian Karthikeyan , Wu Jian-Hui , Rigney David A. 
Published: April 2011

AbstractThe formation of tribomaterial during sliding is well documented for a wide range of materials. Transfer, adhesion, mechanical mixing and formation of nanocrystals are commonly reported, but the mechanisms involved have not been well understood. Recently, molecular dynamics (MD) simulations have been performed to obtain new information on the response of materials to sliding interactions. The results help to explain experimental observations on simple metals such as copper, bulk metallic glasses and multi-component nanocomposite coatings. When the sliding speed is sufficiently high, the strain rate allows vorticity to develop. It is suggested that the resulting eddies are largely responsible for frictional energy dissipation and mechanical mixing in both crystalline and amorphous materials and for the shear mixing of soft embedded particles in nanocomposite coatings. Similarities of flow behavior with that of fluids are noted.
Grain Size Distribution Effect on Mechanical Behavior of Nanocrystalline Materials
Authors: Sergueeva A.V. , Mara N.A. , Mukherjee A.K. 
Published: April 2011

AbstractGrain size distribution effect on the mechanical behavior of NiTi and Vitroperm alloys were investigated. Yielding at significantly lower stresses than found in equiaxed counterparts, along with well defined strain hardening was observed in these nanocrystalline materials with large grains embedded in the matrix during tensile deformation at temperatures of 0.4Tm. At higher temperature the effect of grain size distribution on yield stress was not revealed while plasticity was increased in 50% in NiTi alloy with bimodal grain size structure.
Theoretical Investigations of Polymer Based Solar Cells
Authors: Echols Robert S. , France Chris E. 
Published: April 2011

AbstractWe investigate the behavior of a polymer blend (M3EH-PPV:CN-ether-PPV) bulk heterojunction solar cell using a numeric model that self-consistently solves Poisson's equation and the charge continuity equation while incorporating electric field dependent mobilities. We obtain good quantitative agreement with present experimental data for J-V curves and photocurrent action spectra. To reproduce experimental photocurrent action spectra, our model predicts 36% exciton dissociation efficiencies in the bulk of the polymer. We also study the limiting conditions of polymer solar cell development by simulating an ideal solar cell using an AM1.5 global spectrum and assuming all absorbed photons hitting a M3EH-PPV:CN-ether-PPV polymer blend (band gap ∼2.0 eV) based solar cell at normal incidence contribute to current. If such a solar cell has 100 nm length, open circuit voltage=0.6 V and 50% fill factor, then the maximum theoretical power conversion efficiency is ηp=5.6%. A similar analysis for a M3EH-PPV:PCBM bulk heterojunction cell yields, ηp=3.5%. These results further highlight the need to develop smaller band gap materials and help explain why the best polymer based solar cells have power conversion efficiencies that remain stuck at about 3%. Our model is used to investigate the important increase in power conversion efficiencies we can expect as lower band gap polymers become available.
The fabrication of self-assembling peptides into nanofiber scaffolds through molecular self-assembly
Authors: Zhao Xiaojun , Dai Jessica , Zhang Shuguang 
Published: April 2011

AbstractWe designed and fabricated a class of self-assembling peptides into nanofiber scaffolds. KLDL-12 has been shown to be a permissible nanofiber scaffold for chondrocytes in cartilage 3-D cell cultures. However, the biochemical, structural, and biophysical properties of KLDL-12 remain unclear. We show that KLDL-12 peptides form stable β-sheet structures at different pH values and that KLDL-12 and RIDI-12 self-assemble into nanofibers. The nanofiber length, though, is sensitive to pH changes. These results not only suggest the importance of electrostatic attraction or repulsion affecting the fiber lengths but also provide us with useful information for rational design and fabrication of peptide scaffolds.