bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microcrystalline Keratin: From Feathers To Composite Products
Authors: Schmidt Walter F. 
Published: April 2011

SUMMARYMolecular order and morphological order are two characteristics of feather fiber that make it unique. The fiber is highly microcrystalline and is very durable, i.e., resistant to both mechanical and thermal stress. Feather structure at the microscopic level is a complicated mixture of straight and branched fibers held together by a central fiber to form specific macroscopic structures. The proper design of processes to incorporate feathers into composite products 1) preserves the fiber's molecular properties and 2) alters its micro-/macroscopic morphology to conform to existing composite process requirements.
Electrospinning of Polycarbonates and their Surface Characterization using the SEM and TEM
Authors: Krishnappa Ravi V.N , Sung Changmo , Schreuder-Gibson Heidi 
Published: April 2011

ABSTRACTUnlike conventional spin methods, electrospinning is capable of yielding fibers with sub-micron range diameters and high specific surface areas. The use of such electrospun materials in applications, whose functionality depends on the area available, such as separation processes, will be useful. In this study a Bisphenol-A polycarbonate was dissolved in two solvents: Chloroform and a 1:1 mixture of Tetrahydrofuran (THF) and Dimethylformamide (DMF) and resulting polycarbonate solutions were then electrospun to produce polycarbonate fiber-mats. The morphological features of the electrospun polycarbonate fibers have been studied as a function of the solvent used and also as a function of the processing voltage. The studies were conducted using the SEM, TEM and Scion image analysis program. The results indicate bold differences in the fiber morphology and bead density trends with the solvent used. Electrospun polycarbonate fibers exhibit a “Raisin like” puckered structure. Such a structure will enhance the functional efficiency of an electrospun material when used in an area-based application. In addition, studies on crazing of bulk polycarbonate and the surface features of electrospun polycarbonate fibers have been conducted. Results indicate a relation between crazing and the topological features of electrospun polycarbonates.
Microstructure and Mechanical Properties of Silicon Nitride Reinforced Aluminum Matrix Composites Fabricated by Pressure Infiltration
Authors: Peng L.M. , Noda K. , Kawamoto H. 
Published: April 2011

ABSTRACTThe present study aimed to investigate the microstructure and mechanical properties of aluminum matrix composites reinforced with high volume fraction of Si3N4 fabricated by the pressure casting technique, with variations in the composition of matrix alloy and microstructure of preforms. Characterization was carried out by a combination of metallography, flexural and load-controlled fatigue tests to study the flexural strength, fracture toughness and fatigue behavior in the composites. The findings indicated that increasing matrix strength resulted in an increase in flexural strength and fatigue resistance of composites. The fracture toughness of composites increased with the volume fraction of infiltrated tough Al phase. The CIP pressure exerted a significant effect on mechanical properties of composites. The improvement in mechanical properties of composites is associated with the load transfer effect from matrix to the stiffer reinforcement.
High Toughness Ceramic Laminates by Design of Residual Stresses
Authors: Orlovskaya Nina A. , Kuebler Jakob , Subotin Vladimir I. , Lugovy Mykola 
Published: April 2011

ABSTRACTMultilayered ceramic composites are very promising materials for different engineering applications. Laminates with strong interfaces can provide high apparent fracture toughness and damage tolerance along with the high strength and reliability. The control over the mechanical behavior of laminates can be obtained through design of residual stresses in separate layers. Here we report a development of tough silicon nitride based layered ceramics with controlled compressive and tensile stresses in separate layers. We design laminates in a way to achieve high compressive residual stresses in thin (100-150 micron) Si3N4 layers and low tensile residual stresses in thick (600-700 micron) Si3N4-TiN layers. The residual stresses are controlled by the amount of TiN in layers with residual tensile stresses and the layers thickness. The fracture toughness of pure Si3N4(5wt%Y2O3+2wt%Al2O3) ceramics was measured to be of 5 MPa m1/2, while the apparent fracture toughness of Si3N4/Si3N4-TiN laminates was in the range of 7-8 MPa m1/2 depending on the composition and thickness of the layers.
Analysis of the Atomic-Scale Defect Chemistry at Interfaces in Fluorite Structured Oxides by Electron Energy Loss Spectroscopy
Authors: Ito Y. , Lei Y , Browning N.D. , Mazanec T.J. 
Published: April 2011

ABSTRACTGd3+ doped Ce oxides are a major candidate for use as the electrolyte in solid oxide fuel cells operating at ∼500 °C. Here, the effect of the atomic structure on the local electronic properties, i.e. oxygen coordination and cation valence, at grain boundaries in the fluorite structured Gd0.2Ce0.8O2-x ceramic electrolyte is investigated by a combination of atomic resolution Z-contrast imaging and electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM). In particular, EELS analyses from grain boundaries reveals a complex interaction between segregation of the dopant (Gd3+), oxygen vacancies and the valence state of Ce. These results are similar to observations from fluorite-structured Yttria-Stabilized Zirconium (YSZ) bicrystal grain boundaries.
Exploring The Consequences of Negative Triple Junction Energy
Authors: Gupta Gaurav K. , King Alexander H. 
Published: April 2011

ABSTRACTWe have investigated the consequences of negative triple junction energy in grain growth. Two and three-dimensional models for total system energy, incorporating varying triple junction energy are developed. These models show that there is a decrease in overall system energy with grain size corresponding to the driving force for grain growth. Although the free energy available to drive grain growth is reduced under some conditions, it is never removed for any reasonable values of the triple junction energy.
Thermal Characterization of Nanowire Array in a-Al2O3 Matrix
Authors: Borca-Tasciuc Diana-Andra , Chen Gang , Lin Yu-Ming , Rabin Oded , Dresselhaus Mildred S. , Borshchevsky Alexander , Fleurial Jean-Pierre , Ryan Margaret A. 
Published: April 2011

ABSTRACTThermal properties characterization of Bi nanowires is critical in order to validate the predicted enhancement of their thermoelectric figure-of-merit. In this paper we report the effective thermal diffusivity of Bi nanowires array embedded in a-Al2O3 (alumina) template. The composite material consists of 85% alumina and approximately 15% Bi nanowires with a diameter of 40 nm and an average length of 40 [.proportional]m. Measurements are performed along the nanowire axis. A thermal wave is produced at the front side of the sample and it is monitored at the backside through a fast thermoelectric effect. A one-dimensional heat conduction model is used to extract the thermal diffusivity.
Polymerization in Inverse Microemulsion: An Effective Tool to Produce Biodegradable and non Biodegradable Nanoparticles
Authors: Lebon F. , Grandfils C. , Jérôme R. , Barakat I. , Sartore L. 
Published: April 2011

ABSTRACTPotential of polymerization in inverse microemulsions has been illustrated by the preparation of crosslinked nanoparticles with functional groups on the surface. Nonbiodegradable polyacrylamide nanoparticles have been prepared, with the purpose to use these stable monodisperse lattices as enzymatic reactors and in diagnostic applications. Their size is in the 50 to 90 nm range and they contain a model enzyme (alkaline phosphatase) immobilized. In another example, monodisperse biodegradable nanoparticles of polyamidoamines with a size from 90 to 130 nm have been prepared. They are envisioned for intravenous administration because of a low content of non-metabolized material and absence of toxicity.
Self-Energy corrections to DFT-LDA Gaps of Realistic Carbon Nanotubes
Authors: Satta Guido , Cappellini Giancarlo , Casula Francesco 
Published: April 2011

ABSTRACTSince their discovery carbon nanotubes have attracted much interest for their peculiar electronic properties which go from metalic to semiconducting behaviour, depending both on diameter and chirality. The exact vaue of their band gap is obviously a crucial point to be addressed because it enters in the nanotube application as microelectronic devices. By making use of an efficient GW scheme, previousy tested on bulk systems, as well as of a model screening function, we obtained for the first time excitation energies and band-gap vaues for carbon nanotubes. Results for (6,0) and (7,0) will be presented and discussed.
Formation of Gold Nanowires on MgO Surfaces
Authors: Ueda Akira , Mu Richard R. , Saunders Vanessa , Livingston Thurston , Wu Marvin H. , Arantes Vera L. , Henderson Don O. 
Published: April 2011

ABSTRACTGold nanowires were fabricated on the stepped MgO (100) surfaces. The stepped MgO (100) surfaces were produced by polishing (100) surfaces at an inclined angle ∼1° toward a [110] direction. An atomic force microscope image indicates that gold nanowires have grown at the steps on MgO (100) surface with a height of ∼ 2 nm and a width of ∼60 nm.
Characterization of the order-annealing response of nanostructured iron-palladium based ferromagnetic thin-films
Authors: Xu Huiping , Wise Adam T. , Klemmer Timothy J. , Wiezorek Jörg M. K. 
Published: April 2011

ABSTRACTA combination of XRD and TEM techniques have been used to characterize the response of room temperature magnetron sputtered Fe-Pd thin films on Si-susbtrates to post-deposition order-annealing at temperatures between 400-500°C. Deposition produced the disordered Fe-Pd phase with (111)-twinned grains approximately 18nm in size. Ordering occurred for annealing at 450°C and 500°C after 1.8ks, accompanied by grain growth (40-70nm). The ordered FePd grains contained (111)-twins rather than {101}-twins typical of bulk ordered FePd. The metallic overlayers and underlayers selected here produced detrimental dissolution (Pt into Fe-Pd phases) and precipitation reactions between Pd and the Si substrate.
In-situ Analysis of the Chemical Vapor Synthesis of Nanocrystalline Silicon Carbide by Aerosol Mass Spectrometry
Authors: Lee In-Kyum , Winterer Markus , Hahn Horst , Janzen Christian , Lindackers Dirk , Roth Paul 
Published: April 2011

ABSTRACTAn Aerosol Mass Spectrometer (AMS) is a combination of a Quadrupol- (QMS) and a Particle Mass Spectrometer (PMS) and enables the in-situ analysis of gas phase processes for the generation of nanoparticles. Size distributions of ultrafine silicon carbide particles in the range of 104atomic mass units (amu) to 107amu are measured in the PMS. Simultaneously, molecular species up to 300 amu can be detected in the QMS. Aerosols containing nanocrystalline silicon carbide are produced from tetramethylsilane (TMS) by thermal decomposition. In situ process analysis with the AMS as a function of process parameters was performed to elucidate the formation and growth mechanism of SiC nanoparticles.
Temperature Dependence of Electroresistivity, Negative and Positive Magnetoresistivity of Graphite/Diamond Nanocomposites and Onion-Like Carbon
Authors: Romanenko Anatoliy I. , Anikeeva Olga B. , Okotrub Alexander V. , Kuznetsov Vladimir L. , Butenko Yuriy V. , Chuvilin Andrew L. , Dong C. , Ni Y. 
Published: April 2011

ABSTRACTHere we present the result of measurements of electrical resistivity and magnetoresistivity of graphite/diamond nanocomposites (GDNC) and onion-like carbon (OLC) prepared by vacuum annealing of nanodiamond (ND) at various fixed temperatures. GDNC contain particles with a diamond core covered by closed curved graphitic shells. The electrical resistivity of annealed ND is characteristic of systems with localized electrons and can be described in terms of variable hopping-length hopping conductivity (VHLHC). The magnetoresistivity of OLC is negative in the range of field 0<B<2 T, and is positive at B>2 T. The conduction carrier concentration for OLC samples was estimated in the framework of the theory of negative magnetoresistance in semiconductors in the hopping conduction region. The free path length for conducting electrons at liquid helium temperature was estimated from the data on positive magnetoresistivity. The localization length of current carriers was also estimated. The determined parameters are in agreement with proposed structure model of OLC constructed using HRTEM data.
Crystalline-Amorphous Interface: Molecular Dynamics Simulation of Thermal Conductivity
Authors: Alfthan Sebastian von , Kuronen Antti , Kaski Kimmo 
Published: April 2011

ABSTRACTEffect of a crystalline-amorphous interface on heat conduction has been studied using atom-istic simulations of a silicon system. System with amorphous silicon was created using the bond-switching Monte Carlo simulation method and heat conduction near room temperature was studied by molecular dynamics simulations of this system.
Fe/SiO2 Nanocomposite Soft Magnetic Materials
Authors: Hui S. , Zhang Y. D. , Xiao T. D. , Wu Mingzhong , Ge Shihui , Hines W. A. , Budnick J. I. , Yacaman M. J. , Troiani H. E. 
Published: April 2011

ABSTRACTIn an effort to explore new highly resistive soft magnetic materials, Fe/SiO2 nanocomposite materials have been synthesized using a wet chemical reaction approach in which the precursor complex was annealed at various temperatures. The crystallographic structure, nanostructure, morphology, and magnetic properties of the synthetic Fe/SiO2 particles were studied by x-ray diffraction, transmission electron microscopy, and magnetic measurements. The experimental results show that for this approach, the [.alpha]-Fe particles are coated with amorphous silica. The progress of the reaction, the purity of Fe/SiO2 in the synthetic powder, and the Fe particle size are highly dependent on the annealing temperature. By adjusting the annealing temperature, the particle size can be controlled from approximately 20 nm to 70 nm. For the synthetic nanopowder obtained by H2 reduction at 400 °C, there exists a superparamagnetic behavior below room temperature; while for the nanopowders obtained by reduction at higher temperatures, the ferromagnetic behavior is dominant. Based on these studies, optimum synthesis conditions for Fe/SiO2 nanocomposites is determined.
Synthesis of Nanosized Lithium Manganate For Lithium-ion Secondary Batteries
Authors: Wang Hsien-Cheng , Lin Yueh , Wen Ming-Chang , Lu Chung-Hsin 
Published: April 2011

ABSTRACTNanosized lithium manganate powders are successfully synthesized via a newly developed reverse-microemulsion (RμE) process. Monophasic LiMn2O4 powders are obtained after calcining the precursor powders at 700°C. The particle size of the spinel compound significantly depends on the concentration of the aqueous phase. Increasing the water-to-oil volume ratio results in an increase in the particle size. While the aqueous phase is equal to 0.5 M, the size of the obtained LiMn2O4 powder is around 60-70 nm. It is found that the specific capacity of nanosized LiMn2O4 particles is greater than that of submicron particles. The large surface area of ultrafine particles is considered to facilitate the intercalation and deintercalation of lithium ions during the cycling test.
Preparation of Copper Aluminium Oxide by Spray Pyrolysis
Authors: Rim Ji Youn , Song Shin Ae , Park Seung Bin 
Published: April 2011

ABSTRACTCopper aluminium oxide(CuAlO2) particles, a promissing p-type TCO(transparent conducting oxide), were prepared by spray pyrolysis. Delafossite phase of CuAlO2 was obtained when copper nitrate, copper acetate and copper sulfate, divalent copper precursors, were used as copper precursor and aluminium nitrate as aluminium precursors. However, when copper chloride (CuCl, a monovalent copper precursor) was used, the delafossite phase was not obtained regardless of the type of aluminium precursor. The O2-doped CuAlO2 was obtained by using oxygen as carrier gas.
Nanocomposite Coatings - Applications and Properties
Authors: Cayton Roger H. , Brotzman R. W. 
Published: April 2011

ABSTRACTNanocomposite coatings were made by incorporating nano-sized and micron-sized alumina into aqueous and non-aqueous polymer systems. At approximately 50wt% nano-sized alumina a synergistic effect was observed in coating hardness with no degradation in optical properties.
Structure and Nanocrystallites of Ni and NiO Three Dimensional Ordered Macromeshes
Authors: Zhou W.L. , Xu L. , Zakhidov A.A. , Baughman R.H. , Wiley J.B. 
Published: April 2011

ABSTRACTThree dimensional Ni and NiO inverse opal macromeshes were characterized by scanning electron microscope (SEM) and transmission electron microscope (SEM). The octahedral cubes of the macroporous Ni were found mostly grown as single crystals with staking faults and microtwins. There was no preferential growth of these cubes as determined by selected area diffraction pattern (SADP). Some NiO nanocrystals with size of about 5 nm were formed on the surface of inverse Ni opal membrane during etching away of silica spheres. The oxidation of Ni mesh turned it into NiO macromesh with grain size of about 20 nm at 550°C. The nanocrystalline NiO mesh is suitable for further fabrication of three dimensional nanobeads. By annealing the meshes at 650°C, the NiO nanograins grew to a size of over 50 nm. This three dimensional ordered macroporous structure with higher temperature treatment is considered as stable and important for further application.
Microwave Plasma CVD of Silicon Nanocrystalline and Amorphous Silicon as a Function of Deposition Conditions
Authors: Jeung J-H , Lee Hak-Gue , Teng Lihong , Anderson W.A. 
Published: April 2011

ABSTRACTUsing ECR-CVD (electron cyclotron resonance-chemical vapor deposition), we can make amorphous-silicon (a-Si) and nanocrystalline (nc-Si) thin films. We are looking forward to improve the photo/dark conductivity ratio (σp/σd) by measuring the photo and dark current-voltage (I-V). In the ECR deposition, there are several factors which we can control and adjust for improved results, such as the amounts of silane and argon, the vacuum, and the temperature of the substrate. These become the critical factors for ECR deposition in order to make better films. Input gases consist of Ar, 2%SiH4 in He and H2. In the process, SiH4 is decomposed into SiHx. A residual gas analyzer (RGA) gives composition in the plasma. Because Ar possibly etches the substrate and Si is to be deposited, the best RGA signal is obtained with low Ar content. This work serves to correlate process conditions, RGA signals and electrical data. The best RGA signal occurs for 5 mTorr Ar, 60 mTorr SiH4:He, and power of 600 W. Best value of dark conductivity (σd) was 1.53 × 10-9 S/cm and1.58 × 10-5 S/cm for photo conductivity (σp and low value of σd indicate material with fewer defects. Adding extra H2 improves the photo-conductivity (σp). Applications of these films are heterojunction solar cells and thin film transistors. The heterojunction solar cell had a structure of metal grid/ 500°A of aSi:H/p-Si wafer/Ohmic contact. These cells gave an open circuit voltage (Voc) = 0.51 (V) and short circuit current density (Jsc) = 5.5 mA/cm2 under 50mW/cm2 tungsten halogen lamp. Thin film transistors using nc-Si, with gate length/width (L/W) =450/65 gave field effect mobility of 18 cm2/V-s, and Ion/Ioff of 1.25×105.
Using Ion Beams to Modify Nanocrystalline Composites: Co Nanoparticles in Sapphire
Authors: Meldrum A. , Beaty K.S. , Lam M. , White C.W. , Zuhr R.A. , Boatner L.A. 
Published: April 2011

ABSTRACTIon implantation and thermal processing were used to create a layer of Co nanoclusters embedded in the near-surface region of single-crystal sapphire. The Co nanoparticles ranged in size from 2-20 nm and were crystallographically aligned with the host sapphire. Specimens were irradiated with Xe and Pt ions, and the microstructural evolution of the nanoclusters was investigated by transmission electron microscopy. With increasing Pt or Xe ion dose, the Co nanoparticles lost their initially excellent faceting, although they remained crystalline. The host Al2O3 became amorphous and the resulting microstructure consisted of a buried amorphous layer containing the still-crystalline Co nanoparticles. EDS mapping and electron diffraction were used to determine the distribution of the implanted species, and the magnetic properties of the composite were measured with a SQUID magnetometer. The results show that ion beams can be applied to modify and control the properties of ferromagnetic nanocomposites, and, combined with lithographic techniques, will find applications in exercising fine-scale spatial control over the properties of magnetic materials.
Preparation of Line Patterned Mesoporous DAM-1 Thin Films via Pulsed Laser Deposition
Authors: Coutinho Decio , Balkus Kenneth J. 
Published: April 2011

AbstractPatterned mesoporous DAM-1 thin films were prepared on flexible transparent film utilizing the pulsed laser deposition and a line patterning technique. The patterned lines are transferred to the transparent film using a laser printer or copy machine. Laser ablation of DAM-1 onto the patterned substrate followed by a hydrothermal treatment resulted in a densely packed mesoporous film. Upon removal of the patterned lines (i.e. the underlying toner) by ultrasonic treatment in toluene, patterned DAM-1 films were produced.
Formation of Ni/SiO2 and Ag/SiO2 Nanosphere Composites
Authors: Prokes S. M. , Carlos W. E. , Seals Lenward , Lewis Stephen , Gole James L. 
Published: April 2011

AbstractSiO2 nanospheres have been produced via a high temperature evaporation process and they have been Ni or Ag plated using electroless plating solutions. These samples were examined by Atomic Force Microscopy (AFM) and Magnetic Resonance (MR). The initial SiO2 nanospheres were about 30 nm in diameter, and the Ni plating layer resulted in a 25nm thick metallic Ni coverage, while the Ag coverage was estimated to be in the 150 nm range. In the case of the Ni/SiO2 nanosphere composites, the MR signals show the presence of Ni+2 and Ni+3 paramagnetic centers, seen below 40K, and ferromagnetic metallic Ni, which is seen above 40K. The dried Ni plating solution (with no SiO2) shows only the presence of paramagnetic Ni+3. These results suggest that an interfacial reaction at the surface of the SiO2 nanospheres leads to the formation of ferromagnetic Ni, which deposits onto the spheres and forms a ferromagnetic Ni/SiO2 nanosphere composite. In the case of the Ag/SiO2 nanosphere composites, no MR signal is seen from the non-magnetic Ag, but strong paramagnetic behavior has been noted for Co+2, which originates from the plating solution.
Fabrication of Two- and Three-Dimensional Structures of Nanoparticles Using Lb Method and DNA Hybridization
Authors: Takahagi Takayuki , Huang Shujuan , Tsutsui Gen , Sakaue Hiroyuki , Shingubara Shoso 
Published: April 2011

AbstractIn this paper we describe fabrication methods for two types of nanostructures, two- and three-dimensional arrays of gold nanoparticles. Large-scale and high-ordered monolayers of alkanethiol-encapsulated gold particles were fabricated by using Langmuir-Blodgett (LB) method. Three-dimensional nanoparticle arrays composed of gold nanoparticles of two different sizes, which were encapsulated by complementary thiol-capped DNA oligonucleotides, were fabricated by using DNA hybridization. DNA hybridization occurred upon mixing these particles, which resulted in the assembly of three-dimensional nanostructure of gold particles. Scanning electron microscopy observations and UV spectroscopy measurement were performed to confirm the construction of the nanostructures.