bluuebunny/crossref_metadata_2025_split huggingface dataset:
Semt-Solid Processing of Titanium Alloys for Biomedical Applications
Authors: Toloui B. , Wood J. V. 
Published: June 2019

ABSTRACTAmong metallic systems, titanium alloys are prime candidate materials for biomedical applications in view of their apparent properties in the body environment. While machined and forged parts of CPTi, or Ti-6Al-4V, are suitable for many applications, they are not economical for one-off objects or artefacts of extreme intricacy. Titanium castings are an obvious solution to the problem but these are extremely difficult to process without contamination. Alloying allows a lowering of the melting point and significantly reduces the risk of contamination but the resultant alloys are normally brittle due to networks of intermetallics forming. This paper describes a process of semi-solid casting using a powder titanium feedstock for making one-off castings of artefacts like those required in dentistry. The process will be described and the mechanical and corrosion properties of several alloys which are compatible with this technique are assessed. The basic process is relatively inexpensive and provides a useful tool for examining a wide range of potential titanium base alloys.
Fractured Steinmann Threaded Fixation Pins Following Vertebral Body Resection and Stabilization: Medical Device Pathological Analysis of Two Cases
Authors: Kossovsky Nir , Dujovny Manuel , McDonnell Dennis , Kossowsky Ram 
Published: June 2019

ABSTRACTVertebral body resection in the treatmenL of metastatic neoplasms of the spine is increasingly common for radioresistant tumors. It is also favored for treating progressive neurological disease due to tumor-associated spinal cord compression. Spine stabilization following resection is accomplished by several techniques. Increasing in popularity is the combination of threaded fixation pins and methylmethacrylate filler.In the two cases reported in this communication, failure of threaded AISI 316 stainless steel pins occured through corrosion fatigue. Corrosion begins at the base of the threads and is exacerbated by galvanic cell formation at the methyl methacrylate-bone interface. Fatigue is experienced because the cervical and vertebral bodies are each a part of a joint that normally experiences 10 – 20 degrees of both antero-posterior and lateral flexion.We conclude that in active patients, non-threaded cobalt chrome pins are the preferred material for stabilization of the lumbar and cervical spine following vertebral body resections.
Thermoplastic Polyurethanes Softening in 37°C N-Saline
Authors: Zdrahala Richard J. , Mcgary Charles W. 
Published: June 2019

ABSTRACTThe softening of thermoplastic polyurethane (TPU) in the body environment represents one of the major advantages of these biomaterials. Although the literature contains an abundance of hydrolytic stability data, almost no information exists describing the softening of these materials in the body. A series of polyether-based TPUs, consequently, was synthesized based on 4,4′-diphenylmethane diisocyanate/1,4-butanediol hard segment and polytetramethylene ether glycol soft segment and the effect of simulated body environment (37°C n-saline) was studied as a function of the hard segment content and the soft segment glycol molecular weight. A mechanism and phenomenological analysis of this softening are offered and discussed in terms of TPU morphology. Both water and heat, for example, plasticize the TPU to increase the chain mobility; in the body environment this results in a reversible reduction in elastic modulus.
α-BSM™: A Calcium Phosphate Delivery Vehicle
Authors: Knaack D. , Lee D.D. 
Published: June 2019

Abstractα-BSM™ is an injectable endothermically setting calcium phosphate bone substitute. α-BSM™ has been shown to be effective in promoting the healing of surgically created critical size defects and restoring bone biomechanical strength in several animal models. It has received regulatory clearance for orthopedic indications in both Canada and Europe and for dental and craniofacial indications in the United States.α-BSM™ is distinguished as a bone substitute by its prolonged working time at room temperature, and rapid hardening at body temperature. These properties, as well as its compatibility with a variety of aqueous hydrating agents, make α-BSM™ an attractive vehicle for thein situdelivery of therapeutic agents.In vitrostudies have shown that antibiotics, such as gentamicin, can be stably incorporated into α-BSM™ prior to and during hardening, and that delivery kinetics can be controlled with the appropriate formulation and preparative procedures. The setting reaction is also compatible with biologically active proteins. rhBMP-2 has been incorporated into α-BSM™ and was demonstrated to be effective in stimulating ectopic bone formation in soft tissue and accelerating the restoration of a differentiated phenotype in a rabbit osteotomy model.
Evaluation of the Strain Field Inside and Around Growth Islands by Means of X-Ray Diffuse Scattering
Authors: Schmidbauer Martin , Wiebach Thomas , Raidt Helmut , Schäfer Peter , hanke Michael , Köhler Rolf , Neumann Wolfgang , Kirmse Holm , Rabe Michael , Henneberger Fritz , Wawra Herbert 
Published: June 2019

AbstractThe strain distribution inside and in the vicinity of coherently strained self-organized islands has been investigated by high-resolution x-ray diffraction (HRXRD). Finite element method (FEM) calculations were carried out in order to calculate the strain field, which was then used to simulate x-ray reciprocal space maps on the basis of kinematical scattering theory. For Si0 75Ge0.25 islands an abrupt increase in the Ge-concentration at about one third of the island height has been found. This behavior can be attributed to different nucleation stages during growth. Highly strained buried CdSe quantum dots (QDs) strongly influence the surrounding ZnSe matrix. From reciprocal space maps and FEM simulations we were able to estimate the shape and size of the islands. The results are in agreement with transmission electron microscopy (TEM) and UHV atomic force microscopy (AFM) data.
Identification of Possible High Integrity Containers for Low-Level Nuclear Waste Disposal
Authors: Williams Jeffrey D. 
Published: June 2019

ABSTRACTIncreased concern by the State of South Carolina over the condition and capacity of the low-level radioactive waste burial site at Barnwell has prompted them to promulgate new regulations on waste burial containers. As of September 30, 1981, ion exchange resin and filter media waste with an activity of 1 μCi/cc or greater and with isotopes with halflives greater than five years disposed at Barnwell shall be solidified or confined in a “high integrity container”. The materials and designs of these containers are required to provide waste isolation from the environment for a period of 300 years and provide the structural integrity specified in 49 CFR 173.398(b). HITTMAN has been active in the design and development of containers suitable for this purpose with this paper detailing the analyses involved. Material selections were limited to stainless steel, fiberglass, and polyethylenes. Structural concerns focused on overpressure requirements, drop-testing requirements, and lifting capabilities. With a lifetime dose of up to 108 rads, the possibilities of radiation damage were considered. Preliminary selection of polyethylene was based on satisfactory resolution of these issues and economic factors.
A New Poly-Si CMP Process with Small Erosion for Advanced Trench Isolation Process
Authors: Miyashita Naoto , Uekusa Shin-ichiro , Nishioka Takeshi , Iwami Satoko 
Published: June 2019

AbstractChemical-Mechanical Polishing has been revealed as an attractive technique for poly-Si of trench planalization. Major issue of the process integration is pattern erosion after over polishing. A new process with silica slurry containing organic surfactant is reported in this paper. A patterned wafer after conventional CMP process is eroded by over polishing, however, the new process conducts small erosion for wide trenches. The organic surfactant is well known as a inhibitor for the protection of poly-Si from alkaline, and the new slurry shows a large pH dependency of the viscosity. The experimental work has been focused on the viscosity, and the mechanism of the small erosion is discussed. This new process should be useful for recessing poly-Si by CMP, because it keeps the erosion level very low.
Pattern Formation in Thin Polymer Films: A New Morphology
Authors: Masson Jean-Loup , Green Peter F. 
Published: June 2019

ABSTRACTResearchers have shown that thin, nonwetting, liquid homopolymer films dewet substrates, forming patterns that reflect fluctuations in the local film thickness. These patterns have been shown to be either discrete cylindrical holes or bicontinuous “spinodal-like” patterns. In this paper we show the existence of a new morphology. During the early stage of dewetting, discrete highly asymmetric holes appear spontaneously throughout the film. The nucleation rate of these holes is faster than their growth rate. The morphology of the late stage of evolution, after 18 days, is characterized by a bicontinuous pattern, distinct form conventional spinodal dewetting patterns. This morphology has been observed for a range of film thicknesses between 7.5 and 21nm. The structural evolution of this intermediate morphology is discussed.
Amine-Quinone Polyimides as Coatings that Protect Iron Against Corrosion.
Authors: Han Mijeong , Bie Huimin , Warren Garry W. , Nikles David E. 
Published: June 2019

ABSTRACTA new diamine monomer was synthesized by condensing 4,4'-methylene dianiline with 1,4-benzoquinone. The monomer was condensed with 3,3',4,4'-benzophenone tetracarboxylic dianhydride to give a polyamic acid that was soluble in N-methyl-2-pyrrolidinone. The polyamic acid was cast onto iron and thermally imidized to give the amine-quinone polyimide (AQPI-2). AQPI-2 had a thermal decomposition temperature (10% weight loss) of 540°C and a glass transition near 290°C, values typical of polyimides. The degradation of the coating on iron after exposure to NaCl electrolyte was followed by electrochemical impedance spectroscopy. Under these conditions a conventional polyimide failed after 3 days exposure, while AQPI-2 showed no change after 34 days exposure. The adhesive bond between the amine-quinone polyimide and the iron surface was so strong that it could not be broken by the electrolyte.
Solid-State Blending of Polymers by Cryogenic Mechanical Alloying
Authors: Smith Archie P. , Ade Harald , Koch Carl C. , Spontak Richard J. 
Published: June 2019

ABSTRACTCryogenic mechanical alloying has been employed to blend poly(methyl methacrylate) (PMMA) with up to 25 wt% polyisoprene (PI) and poly(ethylene-alt-propylene) (PEP). Mechanical milling of the individual polymers reveals that their molecular and bulk properties depend sensitively on milling time, post-annealing and, for PMMA, temperature. Characterization of the as-milled blends by scanning transmission x-ray microscopy and transmission electron microscopy has demonstrated intimate (nanoscale) dispersions within the blends, with the degree of mixing increasing with increasing milling time. Phase domains as small as 10 nm are observed after alloying for 10 h. Post-annealing of the blends above the Tgof PMMA (which depends on milling time) induces morphological changes, which differ for blends containing PI and PEP. In blends composed of PEP, the fine dispersions gained as a result of milling are largely compromised. Conversely, PI crosslinking hinders molecular mobility so that the milling-induced nanoscale dispersions of PI in PMMA are, for the most part, retained even after long-term annealing at elevated temperatures.
Measuring Interface Strength in Single Fiber Composites: The Effect of Stress Concentrations
Authors: Holmes G. A. , Peterson R. C. 
Published: June 2019

ABSTRACTFiber-matrix interface strength is known to be a critical factor in controlling the long-term performance of structural composites. This parameter is often obtained by using the average fragment length data generated from the single-fiber fragmentation test (SFFT). The interfacial shear strength is then determined by using this data in a micro-mechanics model that describes the shear-stress transfer process between the matrix and the fiber. Recently, a non-linear viscoelastic micro-mechanics model was developed to more accurately account for the matrix material properties. This new model indicates that the interface strength is dependent on the testing rate. Experimentally, it has been shown that the final fragment length distribution in some systems is dependent on the testing rate. However, data analysis using the new model indicates that the distribution change with testing rate is promoted by the presence of high stress concentrations at the end of the fiber fragments. From the model, these stress concentrations were found to exist at very low strain values. Experimentally, the fragment distributions obtained from specimens tested by different testing rates were found to be significantly different at strain values well below the strain values required to complete the test. These results are consistent with the research of Jahankhani and Galiotis and finite element calculations performed by Carrara and McGarry. These authors concluded that stress concentrations can promote failure of the fiber-matrix interface on the molecular level. Our results support this conclusion. In addition, our research results suggest that altering the SFFT testing rate can lower the magnitude of these stress concentrations and minimize failure of the fiber-matrix interface.
Surface Modification of Poly (alkyl/Arylphosphazene) Thin Films
Authors: John John V. St. , Wisian-Neilson Patty 
Published: June 2019

ABSTRACTPoly (methylphenylphosphazene) (PMPP) is an example of a unique class of inorganic polymers with alternating – (P=N)– backbones. Chemical modification of bulk PMPP can result in changes of physical properties such as chemical resistance, onset temperature of thermal degradation, elasticity, and flexibility. Surface modification of PMPP allows tailoring of the chemical properties at the polymer interface while maintaining the integrity of the bulk polymer. In this research, PMPP thin films were treated to form carboxylate or carboxylic acid groups at the surface. Surface modification was monitored by following changes in contact angle. The hydrophobic/hydrophilic interactions of carboxylated PMPP surfaces allow for mesoscale interactions of thin polymer films.
Radiation Enhanced Porosity and Roughness of Biomaterials
Authors: Evelyn A. L. , Rodrigues M. G. , Ila D. , Zimmerman R. L. , Poker D. B. , Hensley D. K. 
Published: June 2019

ABSTRACTGlassy Polymeric Carbon (GPC), made from cured phenolic resins, is sufficiently chemically inert and biocompatible that it is suitable for medical applications, such as heart valves and other prosthetic devices. We have used energetic ion bombardment of the partially and fully cured precursor phenolic resins to enhance biological cell/tissue growth on, and to increase tissue adhesion to, prosthetic devices made from GPC. GPC samples were bombarded with energetic ions to 10 MeV. The surface topography and increased surface roughness was observed using optical microscopy and atomic force microscopy (AFM). The increased porosity was measured by introducing lithium from a molten LiCl salt into the GPC and using (p, α) nuclear reaction analysis (NRA) to measure the concentration of Li retention in the modified GPC. The NRA measurements of increased pore availability were correlated with the observations of increased surface roughness.
Microcellular Polymeric Foams (MPFs) Generated Continuously in Supercritical Carbon Dioxide
Authors: Siripurapu Srinivas , Gay Yvon J. , Royer Joseph R. , DeSimone Joseph M. , Khan Saad A. , Spontak Richard J. 
Published: June 2019

ABSTRACTMicrocellular polymeric foams (MPFs) hold tremendous promise for engineering applications as substitutes to their solid analogs in light of reduced manufacturing/materials costs and improved properties. We present a two-part study addressing the generation of such materials in the presence of supercritical carbon dioxide (scCO2). The first part describes the production of polystyrene MPFs in a continuous extrusion process, as well as the effect of operating conditions such as temperature and CO2 concentration on foam morphology. The second part discusses microcellular foaming of poly (vinylidene fluoride) (PVDF), a semicrystalline polymer, via blending with the amorphous polymer poly (methyl methacrylate) PMMA. Foams of pure PVDF possess ill-defined morphologies, whereas those of PVDF-PMMA blends show an improvement with cell sizes on the order of 10 mm or less and cell densities in excess of 109 cells/cm3.
An Improved Magnetic Technique For The Non-Destructive Detection Of Faults In Embedded Steel Reinforcement
Authors: Haycock Peter W. , Brown Simon D. , Tomlinson Nicholas , Hocking Matthew J. 
Published: June 2019

ABSTRACTThere are many situations in which steel reinforcement within structural materials is vulnerable to corrosion. In some cases the result of such deterioration of the structural integrity can have significant safety implications. However, there is currently little by way of reliable non-destructive means of obtaining direct evaluation of the state of the embedded steel, which yields anything more than rudimentary information. This paper considers the possibilities of making use of the vectorial nature of the magnetization of steel to improve the qualitative and quantitative evaluation of the integrity of embedded steel reinforcement in vehicle tyres. Results are presented which show that enhanced non-destructive mapping of faults within tyres can be achieved by this means.
Study of Natural Minerals of U-Ryrochlore-Type Structure as Analogues of Plutonium Ceramic Waste-form
Authors: Bogdanov Roman V. , Batrakov Yuri F. , Puchkova Elena V. , Sergeev Andrey S. , Burakov Boris E. 
Published: June 2019

ABSTRACTAt present, crystalline ceramic based on titanate pyrochlore, (Ca,Gd,Hf,Pu,U)2Ti2O7, is considered as the US candidate waste form for the immobilization of weapons grade plutonium. Naturally occuring U-bearing minerals with pyrochlore-type structure: hatchettolite, betafite, and ellsworthite, were studied in orders to understand long-term radiation damage effects in Pu ceramic waste forms. Chemical shifts (δ) of U(Lδ1)– and U(Lβ1) – X-ray emission lines were measured by X-ray spectrometry. Calculations were performed on the basis of a two-dimensional δLá1- and δLδ1- correlation diagram. It was shown that 100% of uranium in hatchettolite and, probably, 95-100% of uranium in betafite are in the form of (UO2)2+. formal calculation shows that in ellsworthite only 20% of uranium is in the form of U4+ and 80% of the rest is in the forms of U5+ and U6+. The conversion of the initial U4+ ion originally occurring in the pyrochlore structure of natural minerals to (UO2)2+ due to metamict decay causes a significant increase in uranium mobility.
Dry Patterning of Cu(Mg) Alloy Films Using a Self-Aligned MgO Mask In an Oxygen Plasma Plus H(hfac) Chemistry
Authors: Yang Heejung , Ko Yeonkyu , Lee Jaegab 
Published: June 2019

AbstractA self-aligned surface MgO layer was used as a mask for dry etching the Cu(Mg) alloy films using an O2 plasma and H(hfac) chemistry. The surface MgO layer was formed by diffusion of Mg from Cu film to the free surface. Cu(4.5at%Mg) film having thickness of 300nm was annealed in O2 ambient at 10 mTorr, 500°C for 30min, followed by the patterning of the MgO layer using photolithography and HF wet etch process. The patterned MgO layer successfully served as a hard mask for dry etching the Cu(Mg) alloy films with a taper slope. In addition, the high quality self-aligned MgO layer was formed upon annealing the Cu(4.5 at.% Mg) alloy films at the low temperature of 300°C. Furthermore, the surface MgO layer grown on Cu(2.3at.% Mg) alloy films at 500°C withstood as a hard mask for dry etching, and thus achieving the patterned copper alloy lines with the low resistivity of 2.2 μΩ-cm. Consequently, this novel etch process using a self-aligned MgO mask can be used for patterning the low resistivity copper alloy lines with a low thermal budget, which is suitable for large-size TFT-LCDs.
Laser Thermal Processing of Alternate Dopants in Silicon
Authors: Clark Mark H. , Jones Kevin S. , Rendon Michael , Gable Kevin A. 
Published: June 2019

AbstractTraditionally, the choice of dopant has been limited to those species with the highest solid-solubility, however, Laser Thermal Processing (LTP) is not fundamentally limited by solid-solubility. Therefore, it is of interest to evaluate alternate dopants that have previously been excluded due to low solid-solubility. To this end, alternate dopants of 14N, 121Sb (n-type), 27Al, 70Ga, and 115In (p-type) are compared to conventional dopants of As and B respectively, after LTP and post-LTP thermal processing. Dopants were implanted into <100> silicon wafers of opposite background doping type that had previously been amorphized to a depth of approximately 300 angstroms by a 15 keV 28Si+ implant of 1x1015/cm2 dose. An implant energy of 5 keV was sufficiently low to confine the implanted ions to the amorphous layer, with the exception of B, which required an energy of 2 keV. All species were implanted at doses of 1x1014, 5x1014 and 1.5x1015/cm2. Samples were LTP utilizing a 308 nm, 18 ns laser pulse with a fluence of 0.680 J/cm2. Post-LTP thermal processing of the samples consisted of a 900 °C rapid thermal anneal (RTA) in a nitrogen ambient for a duration ranging from spike to 300 seconds. Measurements of the sheet resistance, mobility and carrier concentration were taken after both LTP, and the post-LTP thermal processing. Experimental results show that LTP of alternate dopants increases the electrically active carrier concentration of Ga, Al and Sb above solid-solubility. Additionally, the amount of deactivation upon post- LTP thermal processing depends on the alternate dopant species.
Electromagnetic Induction Heating for the 70 nm Node
Authors: Thompson Keith , Booske John H. , Cooper R.F. , Gianchandani Y.B. 
Published: June 2019

AbstractElectromagnetic heating provides a novel alternative to “illumination-based” rapid thermal processing techniques. Exposure to radiation, in the RF and microwave frequency regimes, rapidly heats silicon (∼125°C/sec) to temperatures in excess of 1000°C without the use of a susceptor. These ramp rates make this technology suitable for the activation of shallow implanted dopants, and satisfaction of the 100 nm technology node has been achieved. Furthermore, the presence of high frequency electric fields creates ponderomotive forces that may alter the kinetics of dopant activation and diffusion. These additional driving forces could, once fully understood, lead to an enhanced activation mechanism that activates sufficient dopants to satisfy the 70 nm technology node at temperatures less than 1000°C.