bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Biology of Corrosion and Wear Debris from Orthopedic Implants
Authors: Jacobs Joshua J. , Glant Tibor T. 
Published: April 2011

AbstractBone loss (osteolysis) following total joint arthroplasty has been a subject of increasing concern in the orthopedic research community. Depending on the distribution and severity, bone loss can lead to aseptic loosening, periprosthetic fracture and formidable reconstructive problems at revision surgery. Bone loss is believed to be primarily a response to particulate wear and corrosion debris derived from the prosthetic materials. Phagocytosed particulates activate macrophages and osteoblasts (and perhaps fibroblasts) to produce factors which stimulate osteoclastic bone resorption and reduce osteoblastic bone formation. To investigate the responses of these cells to particulate corrosion and wear debris, in vitro studies have been performed by measuring factors at both the molecular and cellular levels that may trigger, maintain and/or regulate particulate biomaterial-induced pathologic bone resorption. The biological effect of a particulate species depends upon their size, concentration (number) and composition, in the order listed. Particulate wear debris of phagocytosable size (less that 10 micrometers) activate macrophages, fibroblasts and osteoblasts more effectively that those of larger sizes. As a response to phagocytosed particulates, i) macrophages produce a number of cytokines (interleukins such as II-1, II-6, TNF-alpha) and prostaglandins, which may act either in an autocrine fashion or further stimulate cells present in the periprosthetic tissue; ii) fibroblasts secrete active forms of metalloproteinases; and iii) osteoblasts have diminished collagen type I synthesis. Taken together, particulate corrosion and wear debris provoke a series of biological responses which generate an active microenvironment around prosthetic components. Strategies to modify the host response to particulate degradation products have emerged from these in vitro studies. These strategies may provide pharmacotherapeutic solutions to this important clinical problem.
Phase Inversion Dynamics of PLGA Solutions Related to Drug Delivery
Authors: Mchugh A.J. , Graham P.D. , Brodbeck K.J. 
Published: April 2011

AbstractDark ground optical microscopy, electron microscopy, and protein release rate studies have been used to quantify the effects of formulation changes on the phase inversion dynamics and in vitro drug release properties of an injectable PLGA-based drug delivery system. Gel growth rates and water influx rates are determined from plots of the square of the respective front with time. Results show that additives that increase the solution gelation rate and produce finger-like void morphologies result in higher initial release rates. Conversely, additives that slow the rate of gelation dramatically reduce the initial drug release rate and lead to a more dense sponge-like morphology.
Novel pH-Sensitive Hydrogels with Peg-Tethered Chains for Oral Delivery of Calcitonin
Authors: Torres-Lugo M. , Peppas N.A. 
Published: April 2011

AbstractMajor challenges in oral delivery of peptides include the need to overcome gastric and intestinal degradation. pH -Sensitive hydrogels are suitable candidates for oral drug delivery of peptides due to their ability to respond to their environment. We have developed a new type of hydrogel composed of poly(methacrylic acid) grafted with poly(ethylene glycol) which can be used as drug delivery carriers for salmon calcitonin. These hydrogels were prepared by free radical solution polymerization and were molecularly designed to contain poly(ethylene glycol) tethered chains promoting mucosal adhesion and providing calcitonin protection, as well as methacrylic acid moieties, which act as calcium binders leading to epithelial cell junction opening. Solutions of approximately 0.1 mg/ml of salmon calcitonin were used to load the protein into the gels at pH = 7 and constant ionic strength of 0.1 M.In vitrorelease studies were performed at pH=7 and 37 °C, while keeping an ionic strength of 0.1 M. Calcitonin release was achieved. The release behavior was explained in terms of diffusional theories.
Small-Angle Neutron Scattering of Bilayer Vesicles Made with Synthetic Phospholipids
Authors: Trevino S. F. , lvkov Robert , Matyas Gary R. , Lebeda Frank J. 
Published: April 2011

AbstractWe have used Small-Angle Neutron Scattering to investigate the structure of bilayer lipid membranes in aqueous solution. The lipids consist of equimolar concentrations of two molecules DMPG and DMPC (see text). The structures consist of solvent filled cores surrounded by shells composed of the lipid bilayers. In particular the radii of the core and shell thickness are measured as a function of lipid concentration and temperature. Other features which reveal themselves are vesicle forming ability of the lipids, additional larger structures and inter-vesicle interactions at large vesicle concentrations. The study is motivated by the possible use of these systems as delivery vehicles for various beneficial therapeutic compounds.
Production of Zirconium-Based Glassy Alloy Wires by Melt Extraction Method and Their Mechanical Properties
Authors: Katsuya A. , Inoue A. 
Published: April 2011

AbstractGlassy Zr65Al10Ni10Cu15 wires were produced in the diameter range up to about 310 µm by a melt extraction method using a copper wheel in an argon atomospher The grass transition temperature (Tg) and crystallization temperature (Tx) are 652K and 757K, respectively, and the temperature interval of the supercooled liquid, ΔTx(=Tx-Tg) is 105K, in agreement with those for the corresponding melt-spun ribbon. The wires have a nearly real circular cross section and good mechanical properties.
On the Effect of Al on the Formation of Amorphous Mg-Al-Cu-Y Alloys
Authors: Ohnuma M. , Linderoth S. , Pryds N. , Eldrup M. , Pedersen A. S. 
Published: April 2011

AbstractThe bulk amorphous alloy (Mg1-xAlx)60Cu30Y10 has been studied, in particular the influence of Al concentration on the glass forming ability and on the various transition temperatures. The amorphous single phase has been obtained for x up to 0.07 by casting into a wedge-shaped copper mold. The amorphous alloys were investigated by differential scannning calorimetry (DSC). All the specimens with x = 0 - 0.07 show a clear glass transition. The crystallization temperature decreases with increasing Al concentration, while the temperatures of the glass transition, melting and solidification change only slightly. The DSC measurements show that for Al contents below 0.05 the first exothermic peak which corresponds to crystallization, consists of two overlapping peaks. To clarify the origin of the splitting of the first exothermic peak, the crystallization process of Mg60Cu30Y10 alloy has also been studied by x-ray diffraction.
Continuous Amorphization of Zr-Based Alloys by Controlled Mechanical Intermixing
Authors: Wilde G. , Sieber H. , Perepezko J. H. 
Published: April 2011

AbstractBinary Zr-(Cu, Ni, Al) alloys were mechanically intermixed by cold-rolling stacks of elemental foils. The results indicate that solid-state amorphization is initiated if the grain size of the Zr-Cu and Zr-Ni alloys falls below a critical value. Amorphization was not observed for the Zr-Al alloy. These results are in accordance to the predictions of a model for solid-state amorphization. The comparison with the results on a quaternary Zr-Cu-Ni-Al alloy indicate the influence of multicomponent alloying on the glass-forming ability of Zr-rich alloys by mechanical working.
Characterization of Gas Atomized Cu48Ti34Zr10Ni8 Amorphous Metal Powder
Authors: Foley J. C. , Sordelet D. J. , Lograsso T. A. 
Published: April 2011

AbstractThe advent of multi-component metallic alloys, which exhibit relatively good glass forming ability, has opened opportunities for processing metallic glasses into thick cross section components. The relatively good glass forming ability is important because conventional processing techniques (e.g., casting, extrusion and rolling) may be used to fabricate useful shapes while retaining the excellent engineering properties of an amorphous structure. In particular, the favorable processing characteristics of bulk amorphous alloys are the low cooling rates which can be exercised to yield an amorphous structure and the operating temperature range between the glass transition temperature (Tg) and the crystallization temperature (Tx). Current work is focused on developing a processing strategy that will allow us to fabricate even larger cross section amorphous alloys than are currently achievable by casting methods. The technique involves producing high pressure gas atomized (HPGA) Cu48Ti34Zr10Ni8 powders and consolidating them at temperatures above Tg, but below Tx. Thermal analysis of atomized powders by DSC provides details of the influence of powder particle size, which is related to cooling rate during atomization. The results of experiments characterizing the thermal and kinetic behavior of Cu48Ti34Zr10Ni8 powders indicate that short processing times are required to retain the amorphous structure during consolidation in the temperature regime between Tg and Tx.
Formation of Glassy Spinodals in Bulk Metallic Glasses
Authors: Guo W. H. , Leung C. C. , Kui H. W. 
Published: April 2011

AbstractWhen a eutectic alloy melt is undercooled well below its liquidus T1, liquid state phase separation occurs. The liquid morphologies can be frozen by subsequent crystallization. It was found that for Pd82Si18 when rapid quenching is also employed, ore of the phase-separated liquids after solidification is amorphous. The undercooled specimen is in bulk form with a diameter of ∼ 5 mm.
Effect of Small Amounts of B and C Additions on Glass Formation and Mechanical Properties of a Zr-Base Alloy
Authors: Liu C. T. , Pike L. M. , Chen N. G. 
Published: April 2011

AbstractThe effect of B and C additions up to 0.4 at. % on glass formation and mechanical properties of a Zr-base alloy Vitreloy 105 was studied using various techniques. All alloys were prepared by arc melting and drop casting. Boron additions increase the glass forming ability by lowering Tm and increasing Tg. Carbon additions only lower Tm but not affect Tg. B and C additions occupy free space and do not harden the glass phase.
Exelfs of Metallic Glasses
Authors: Ito Y. , Alamgir F. M. , Jain H. , Williams D. B. , Schwarz R. B. 
Published: April 2011

AbstractThe feasibility of using extended energy-loss fine structure (EXELFS) obtained from ∼1 nm regions of metallic glasses to study their short-range order has been examined. Ionization edges of the metallic glasses in the electron energy-loss spectrum (EELS) have been obtained from PdNiP bulk metallic glass and Ni2P polycrystalline powder in a transmission electron microscope. The complexity of EXELFS analysis of L- and M-ionization edges of heavy elements (Z>22, i.e. Ni and Pd) is addressed by theoretical caluculations using an ab initio computer code, and its results are compared with the experimental data.
Microforming of Mems Parts with Amorphous Alloys
Authors: Saotome Yasunori , Zhang Tao , Inoue Akihisa 
Published: April 2011

AbstractMicroformability of new amorphous alloys in the supercooled liquid state and microforming techniques for the materials are shown. In the supercooled liquid state, the materials reveal perfect Newtonian viscous flow characteristics and furthermore exhibit an excellent property of microformability on a submicron scale. As for microforming techniques, microforging and micro extrusion of amorphous alloys are introduced in addition to the fabrication method of micro dies of photochemically machinable glass. As a result, amorphous alloys are expected as one of the most useful materials to fabricate micromachines.
Thermal Stability of Bulk Metallic Glasses. Influence on Mechanical Properties
Authors: Pelletier J. M. , Jacquemard Y. , Perez J. , Bathie R. Perrier de la 
Published: April 2011

AbstractTwo Zr-base bulk metallic glasses were investigated in the present work. DSC experiments were performed at different heating rates (dT/dt). Evolution of the characteristic temperatures, glass transition and onset of crystallisation, were determined as a function of dT/dt. Evolution of shear elastic modulus and internal friction are measured as a function of temperature and resulting microstructural evolution; these evolutions are related to variation of the atomic mobility.
Residual Stresses in Bulk Metallic Glasses due to Differential Cooling or Thermal Tempering
Authors: Ustundag E. , Clausen B. , Hanan J. C. , Bourke M. A. M. , Winholtz A. , Pekers A. 
Published: April 2011

AbstractDue to their very low thermal conductivities and large thermal expansion values, bulk metallic glasses (BMGs) undergo differential cooling during processing. Large thermal gradients are generated across a specimen leading to residual stress buildup. A thin surface layer contains compressive stresses balanced by tension in the middle. Such stresses can not only influence the mechanical behavior of BMGs, but they can also lead to problems during manufacturing of large or intricate components. Analytical and finite element modeling was used to predict the values and distribution of such stresses as a function of processing conditions. Neutron diffraction measurements were then performed on model specimens which included crystalline phases as “strain gages”. It was shown that significant stresses, on the order of several hundred MPa, can be generated in BMGs. Modeling and diffraction results are presented and their implications discussed.
Thermodynamics and Glass Forming Ability from the Liquid State
Authors: Desre P. J. 
Published: April 2011

AbstractThis study is mainly devoted to the establisment of relations between easy glass forming ability of some multicomponent liquid alloys and strong heteroatomic bonding in connection with nucleation. The chemical short range order in typical liquid bulk glass formers as Zr-Ni-AI is evaluated from a statistical model and presented as Cowley's order parameters versus concentration. The effect of the nature and of the number of components on the chemical contribution to the liquid-crystal interface energy and on the Gibbs energy of crystallisation is analysed and discussed. A specific mechanism of nucleation based on a distribution of concentration fluctuations in the undercooled liquid is proposed. This homophase fluctuation mechanism, which is thermodynamically and kinetically justified, leads to a lower preexponential factor in the expression of the frequency of nucleation as a function of the number of components. Furthermore, this frequency of nucleation can be strongly lowered by an augmentation of the energy barrier of nucleation depending on the nature and the number of components in the liquid phase.
The Kinetic Investigation of the Deposition of Alumina and Aluminosilicates from Mixtures of SiCl4, AlCl3, CO2, and H2
Authors: Nitodas Stephanos F. , Sotirchos Stratis V. 
Published: April 2011

AbstractThe codeposition of alumina, silica, and aluminosilicates from mixtures of silicon tetrachloride, aluminum trichloride, carbon dioxide, and hydrogen is investigated in this study. Chemical vapor deposition experiments are carried out in a hot-wall reactor of tubular geometry coupled with an electronic microbalance. In order to elucidate some aspects of the codeposition process, the deposition of pure alumina and pure silica from mixtures of silicon tetrachloride and aluminum trichloride, respectively, with CO2 and H2, is also investigated. Among the most interesting findings of our study is that the presence of AIC13 has a catalytic effect on the incorporation of silica in the deposit, leading to codeposition rates that are higher than the deposition rates that are obtained when only one of the two chlorides (SiCI4 or A1C13) is present in the feed
Silicon Nitride Coatings Formed using the Selective Area Laser Deposition (SALD) Technique
Authors: Sun Lianchao , Shaw Leon L. , Marcus Harris L. 
Published: April 2011

AbstractIn this paper, the Selective Area Laser Deposition (SALD) technique was used to deposit silicon nitride material from the gas phase. Tetramethylsilane (TMS) and ammonia were chosen as precursors for silicon and nitrogen respectively. Effects of processing temperatures and gas ratios of TMS to total pressure (PTMS+ PNH3) on the relative amounts of silicon nitride and the growth kinetics were studied. Further, surface morphology and electrical properties of the deposits were also examined. It is found that the as-deposited materials are mainly composed of amorphous phases and the heat-treated samples (at 1500°C for 8hrs) consist of α-Si 3N4, α-SiC and β-SiC. The amount of αz-Si3N4decreases with the increase of the TMS pressure. The volume growth rate of deposits also increases with the TMS pressure. The apparent activation energy for these processes is estimated as 1 OOkJ/mol.
Zirconia Coatings Deposited by Inductively Coupled Plasma Assisted CVD
Authors: Colpo P. , Ceccone G. , Leclercq B. , Salvatore P. , Rossi F. 
Published: April 2011

AbstractThin films of zirconia have been deposited by an Inductively Coupled Plasma Assisted CVD (ICP-PACVD) reactor from tetra (tert-butoxy)-zircon precursor diluted in Ar and O2gas mixture. An independent RF generator is used to control carefully the substrate negative bias voltage during the deposition. Zirconia thin films, with thickness up to 10 microns were deposited on Si (100) polished wafers under different plasma conditions. Correlation between deposition parameters, and microstructure has been established showing that the ion bombardment has a large influence on the coating characteristics. In particular, the possibility of tailoring mechanical properties of the films by controlling the applied DC bias voltage is discussed.
CCVD: Low-Cost Vapor-Deposition of Thin Films in Open Atmosphere
Authors: Schmitt Jerome J. 
Published: April 2011

AbstractThe new, patented Combustion Chemical Vapor Deposition (CCVD) process holds promise for low cost, high throughput manufacturing of thin film ceramic coatings with composition and microstructure tailored for specific applications in electronic, optic, anti-corrosion and anti-wear applications. The flame-based CCVD process is an open-air, non-vacuum, environmentally friendly process with the ability to produce coatings of equal or superior quality to those produced by conventional vacuum-based methods. Capital and operating costs for CCVD coating systems are significantly lower than, for example, conventional CVD and PVD technologies. As an open-atmosphere process, ccvD can be easily implemented in a continuous production line environment, avoiding the need for vacuum load-locks. MicroCoating Technologies has used CCVD to deposit over 60 different inorganic materials onto a variety of substrates ranging from metals and polymers to ceramics. Multi-layered films of complex composition have been achieved with excellent stoichiometric control. We review the CCVD process and characteristics of representative coatings
Photo Chemical Modification of the ZnSe Surface
Authors: Stepanenko Victor M. 
Published: April 2011

AbstractPhoton stimulated reaction of chlorine at ZnSe surface was observed at room temperature in the photon range from 4 eV to 12 eV. Estimated quantum efficiency is about 1, depending on the photon range and gas pressure. The study of reaction products was performed with AES, XPS and SEM with Energy Dispersion Analysis. A model based on photon stimulated diffusion of dissociated gas atoms is dicussed. Comparison to C12/GaAs and XeF2/Si systems was made.Effective laser ablation of the ZnCI2 films deposited with masks was exploited for direct patterning. The ultimate resolution obtained was restricted with diffraction limit,
Diamond-Like Nanocomposite Films Fabricated in an Acetylene Atmosphere by Ion Beam Assisted Deposition: XPS Analysis
Authors: Wang Paul W. , Sulak Jodi L. , Ding Xing-Zhao , Zhang Fu-Ming , Liu Xiang-Huai 
Published: April 2011

AbstractDiamond-like nanocomposite (DLN) film, by embedding the diamond-like carbon into an amorphous SiO2 network, is a special class of modified diamond-like carbon (DLC) coating, which shows many excellent properties and potential applications. In this work, DLN films were fabricated in an acetylene atmosphere by ion beam assisted deposition. However, in order to understand the mechanical and electronic properties of the DLN film separation of the sp3 carbon bond from sp2 bond is necessary, because the former determines the hardness and the latter is related to the optical gap and electrical conductivity. Here we report the effect of the annealing on the relative concentrations of sp3 and sp2 hybrids in the film by using the XPS technique to decompose the C ls signal into sp3 and sp2 components. The XPS results clearly indicate that the distribution of the sp3 and sp2 C species is modified by thermal annealing at 700 °C. More sp3 species accumulate at the interface and gradually decrease towards the film surface.
Deposition and Etching of Amorphous Carbon Films Prepared by ECR-Plasma-Enhanced Benzene Chemical Vapor Deposition
Authors: Chen Xiao-Hua , Tolbert Laren M. , Ning Z. Y. , Hess Dennis W. 
Published: April 2011

AbstractAmorphous hydrogenated carbon thin films have been deposited from benzene vapor in a microwave electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition (CVD) system. Plasma enhanced dissociation and reaction of benzene were monitored by mass spectrometry. Deposited films were characterized by Fourier transform infrared spectroscopy and fluorescence spectroscopy. The effect of the deposition rate on the film density and plasma etch resistance was also studied. The etch resistance of deposited carbon film is higher than the conventional resist Novolac.
Quantitative Analysis of Raman Spectra from Diamond Like Carbon: Calibration Transfer
Authors: Rosenblum S. S. , Davis Kevin L. , Tedesco James M. 
Published: April 2011

AbstractWe report on Raman studies of diamond-like carbon (DLC) films; in particular, we report on the instrumentation and methodology required for comparing Raman measurements taken on different Raman analyzers. Raman spectroscopy has taken on an increasingly important role in materials processing because of its capability of performing non-destructive, in situ characterization of thin films. In particular, noncrystalline carbon coatings have become ubiquitous as protective layers on everything from machine tools to hard disk drives. As tolerances on coating properties begin to play an important part in determining device failure, Raman spectroscopy has found ever greater application as a quality control/quality assurance tool. However, use of Raman as an analytical tool has been hampered by the inability to quantitatively compare spectra obtained with different Raman analyzers. By using automated, robust calibration protocols on both the wavelength and intensity axes, we have demonstrated cross-instrument calibration transfer of DLC films.
The effect of silicon on thermal stability and wear behavior of diamond-like carbon films
Authors: Wu Weng-Jin , Hon Min-Hsiung 
Published: April 2011

AbstractThe diamond-like carbon (DLC) films added with silicon content from Oat% to 19.2at% were deposited using R.F. PECVD. By increasing the annealing temperature the groups of CHn and Si-H in FTIR spectra of the deposited films decrease because of hydrogen evolution, whereas the intensity of C=O and Si-O peaks increases due to oxidation. From Raman spectra, the observable shoulder of D band occurs at 400°C and 500°C respectively, which indicates that the addition of silicon improves the thermal stability of DLC films. A pin-on-disk wear test was conducted to investigate the wear behavior of the DLC films. DLC film with small amount of silicon addition has a lower friction coefficient (0.01) than the undoped one(0.1). Raman analysis showed that in wear test the graphitization of pure DLC film occurs at the initial stage whereas for the silicon containing DLC, graphitization of wear debris or transferred film was not observed after the wear test.