bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early Fatigue Damage In Carbon Fiber Composites Observed By Electrical Resistance Measurement
Authors: Wang Shoukai , Shui Xiaoping , Fu Xuli , Chung D. D. L. 
Published: June 2019

ABSTRACTEarly fatigue damage during the first tenth (or less) of the fatigue life was observed in carbon fiber composites by DC electrical resistance measurement. The damage was most severe in the first loading cycle and the incremental damage in each subsequent cycle diminished cycle by cycle. For the continuous carbon fiber carbon-matrix composite, the resistance increased irreversibly during early fatigue due to matrix damage and possibly fiber fracture as well. For the short carbon fiber polymer-matrix and cement-matrix composites, the resistance decreased irreversibly during early fatigue due to matrix damage near the junction of adjacent fibers and the resulting increase in the chance that adjacent fibers touched one another.
Surface Roughness Characterization of al Films by Spectroscopic Ellipsometry
Authors: Blanco J. R. , Vedam K. , McMarr P. J. , Bennett J. M. 
Published: June 2019

ABSTRACTWell characterized rough surfaces of aluminum films have been studied by the nondestructive technique of Spectroscopie Ellipsometry (SE). The roughness of the aluminum specimens had been characterized earlier by Total Integrated Scattering and Stylus Profilometry techniques to obtain numerical estimates of ras roughness and autocovariance lengths. The present SE measurements on these specimens were carried out at a number of angles of incidence in the range 30–80° and at a number of discrete wavelengths in the spectral range 300–650nm. The SE results were then analyzed by the scalar theory of diffraction from random rough surfaces by treating the surface as a simple random rough surface. The results of such analyses of the SE measurements are compared with the results of the earlier characterization techniques.
Experience in Reconstructive Surgery of Craniomaxillofacial Deformities: With Osteomesh, Eleven Years Experience
Authors: Habal Mutaz B. , Leake Donald L. 
Published: June 2019

ABSTRACTThe best possible implantable biomaterial for bony contour abnormalities is autogenous bone grafts. However, some conditions may be present that require use of alloplastic materials. Such alloplastic material must be inert and there should be no reaction in the body to it. The composite graft described in this chapter is a combination of the two different materials described. To have a better take, the bone graft used is ground with a craniotome, and then mixed with blood. This produces an inductive matrix that promotes osteoneogenesis. The alloplastic material is a tray or a template where the bone is placed “in”, “on”, or “under” the implant to allow for complete solidification and better healing. The material used is polyetherurethane-impregnated terephthalate (Dacon) also referred to as osteomesh (R) (Xomed Corporation, Jacksonville, Florida). In a few instances the osteomesh was removed and we noted complete solidification of the bone (resembling skull in the case of the skull defect). For over eleven years, since the success in the experimental animal [1], this composite graft was used in clinical situations with good success [2] in over 100 patients. These patients treated were selected and a strict set of indications and contraindications were instituted and implemented, prior to the applications of this treatment in the individual patient.
Mechanisms of Failure of Arterial Prostheses
Authors: Wesolow M. D. Adam 
Published: June 2019

ABSTRACTOne of the most successfully applied classes of biomaterials is the porous textile vascular prosthesis. Experimental and clinical investigations have been continuously conducted during the past thirty years to study tissue healing, clinical longevity and improved design of these prostheses. The vascular device retrieval program has enabled classification of the 40 or more identified mechanisms of failure of arterial prostheses into the following major groupings: A. Failure of diagnosis B. Error in implantation C. Patient contribution D. Complications of healing E. Fabrication failure F. Infection
Carbon Fiber Reinforced Triazin Resin for Endoprostheses
Authors: Esper F. J. , Harms J. , Mittelmeier H. , Gohl W. 
Published: June 2019

ABSTRACTMetal alloys, ceramics, and thermoplastics are commonly used as materials for endoprostheses, especially artificial hip joints. Prostheses made of these materials still retain disadvantages which have been responsible for failures in the past. A new material, without the abovementioned disadvantages, has been developed. It is a carbon fiber reinforced thermo set based on the triazin resin. Its principle mechanical properties can be matched with those of bone. The new material (referred to as TCF) has a higher bending and fatigue strength than cast metallic alloys if endless fibers are applied. Its creep rate at 37°C under high load (3000 N), as well as its wear rate against metallic or ceramic wear partners, is negligible. Experiments with animals based on ten years of experience show good osteocompatibility of the TCF. Toxic reactions of the tissue caused by the TCF implants themselves, or by fine wear debris found in membranes of connective tissue (or lymph nodes), were not observed at all. Tissue reacts on large particles of TCF wear debris in the same manner as it does on particulates of the same size of polyethylene. It can be expected that the favorable biomechanical and biological properties of the TCF material will make it a good alternative to other materials already in use for construction of endoprostheses, especially hip joints.
Clinical and Laboratory Experience with the use of Titanium and Titanium Type 318 Alloy for Bone and Joint Replacement
Authors: Wright Keith W. J. 
Published: June 2019

ABSTRACTCommercially pure titanium type T5 and titanium type TAl alloy have been used at Stanmore in major bone and joint replacement prostheses since 1963 and 1971 respectively. Because laboratory studies indicated cast CoCrMo alloy to be a superior bearing material both titanium materials have been joined to cast CoCrMo alloy bearing elements to form composite prostheses with no apparent adverse clinical effects.Laboratory studies and clinical experience have shown the inadequacy of the fatigue properties of titanium type T5 and cast CoCrMo alloy for highly stressed intramedullary stems. Nevertheless, although titanium type TAl alloy has superior fatigue properties highly stressed components of this material are not immune to fatigue failure.Wear of U.H.M.W.P.E. appears to be greater when articulated with titanium type TAI alloy than it is when articulated with cast CoCrMo alloy and Al2O3 counterfaces. In addition, capsular tissue which rubs on titanium type TAl alloy can become heavily pigmented. However, to date no clinical complications appear to have resulted from either of these shortcomings. Whether a surface treatment for titanium type TAl alloy such as ion implantation will both improve its wear characteristics with U.H.M.W.P.E. and reduce the amount of metallic material liberated into the soft tissues has yet to be established.
Improvements in the Hardness of Surgical Titanium Alloys by Ion Implantation
Authors: Sioshansi Piran , Oliver Richard W. 
Published: June 2019

ABSTRACTTitanium is generally recognized as one of the most biocompatible metal species, and as such, titanium based alloys are among the top contenders for the material of choice in orthopaedic prostheses. The questionable wear performance of titanium in abrasive and adhesive wearing conditions has been an impediment for a more widespread use of the alloy up to now. The ion implantation process has been shown to be extremely effective, in laboratory experiments, in enhancing the wear performance of the metal and at the same time reducing the wear of ultra high molecular weight polyethylene (UHMWPE) mating surface in contact with the alloy.The present paper focuses on the increased hardness of the Ti-6Al-4V alloy as a result of ion implantation. It is generally believed that the wear improvements of titanium as a result of ion implantation are directly proportional to increased hardness of the surface. Thus, hardness data can be useful for the screening of ion implantation parameters to identify the optimum processing conditions. The Knoop hardness of ion implanted Ti-6Al-4V samples has been measured for B, C, N, N2, O and Ne ion species.
The Effect of Nitrogen Ion Implantation on the Abrasive Wear Resistance of the Ti-6Al-4V/UHMWPE Couple
Authors: Matthews Frank D. , Greer Keith W. , Armstrong Douglas L. 
Published: June 2019

ABSTRACTNitrogen ion implantation was investigated as a means of improving the wear resistance of Ti-6Al-4V alloy and the performance of the Ti-6Al-4V/ultra high molecular weight polyethylene (UHMWPE) wear couple. Included in the pin-on-disc wear study were cobalt-chromium and stainless steel controls as well as non-ion-implanted Ti-6Al-4V. Ion implanted Ti-6Al-4V and the control alloys exhibited minor scratching whereas non-ion-implanted Ti-6AI-4V exhibited definite wear scars. Gravimetric analysis of the UHMWPE discs revealed no significant difference between those worn against ion implanted Ti-6Al-4V and the control alloys. Discs worn against non-ionimplanted Ti-6Al-4V, however, exhibited significantly more weight loss than the other couples. The results of this testing indicate that nitrogen ion implantation improves the wear resistance of Ti-6Al-4V with an attendant decrease in the amount of polyethylene abrasive wear.
Preparation and Characterization of Insulating Polyphenylene Oxide Films on Platinum Electrodes
Authors: Langmuir Margaret E. , Koch V. R. 
Published: June 2019

ABSTRACTPolyphenylene oxide (PPO) polymer films were electrogenerated on Pt substrates from solutions of o-allylphenol (OAP), 2-allyl-4-methylphenol (2A4MP), and 2-allyl-6-methylphenol (2AGMP). Relatively thick (l–20μm) films of the corresponding PPO films were generated from 50 v/o methanol/water solutions of the monomers or at low phenol:KOH concentration ratios. The film thickness depended on the maximum anodic potential to which the electrode was cycled. Films prepared from these solutions were found to be microporous with respect to ion permeability, allowing the oxidation of Br− and reduction of Fe3+ to take place at the Pt surface. Competing oxidation of methoxide ion was found to be the cause of the film porosity and thickening.On the other hand, thin (500–1000Å) coherent insulating films which were impervious to Br− and Fe3+ ions could be deposited from aqueous KOH solutions and from methanolic solutions at high phenol:KOH concentration ratios. The thin films were found to decrease the diffusion rates of hydronium and hydrox hydroxide ions to the electrode surface to a significant degree. As a result, the filmed electrodes could be cycled in neutral saline between +1.5 and −0.2 V vs. SCE with no damage to the film.
Artificially Induced Biological Organs: A New Concept
Authors: Wildevuur Ch. R. H. , van der Lei B. 
Published: June 2019

ABSTRACTThe biological repair process tends to cover a vascular prosthesis by normal arterial wall tissue. This process was successfully utilized in rats to form eventually a neo-artery induced by a temporary physiologically functioning prosthetic scaffold. Essential for the regeneration of a normal compliant neo-artery was the initial physiological campliance and the gradual degradation of the prosthetic grafts. Only then the regenerating neo-media was effectively stimulated by the pulsatile flow to produce elastic laminae. Regeneration of the arterial wall could be enhanced by seeding smooth muscle cells. The same concept was successfully applied to replace the trachea and oesophagus in rabbits. These results demonstrate that regeneration of biological organs can be induced by temporary acting artificial organs, which are anatomically correct and superior to permanently implanted artificially organs.
Fracture Toughness Testing of In Vivo Aged Biomaterials
Authors: Pilliar R. M. , Williams D. F. , Vowles R. 
Published: June 2019

ABSTRACTAlthough mechanical property characterization of materials for loadbearing implant applications is recognized as a necessary prerequisite to theirin vivouse, tests are usually restricted toin vitrosituations becaus-of specimen size and cost limitation. Thisstid7'Jescribes a fracture toughness test that uses small specimens that can be conveniently placed in intermuscular positions in laboratory rats. The method is illustrated for the evaluation of two orthopaedic biomaterials namely bone cement and a filled composite (hydroxyapatite-filled polyethylene). The results indicated little mechanical degradation of the bone cement after 120 daysin vivobut a significant change in the filled polyethylene composite after only 70 days in vivo.
Role of Plasma Proteins in Corrosion of 316L Stainless Steel In Vitro
Authors: Bence J. L. , Black J. , Mitchell S. N. 
Published: June 2019

ABSTRACTPlasma proteins have been recognized as playing a role in the corrosion of metals used as medical implants. In this study, we examined the early events of anodic corrosion of 316L stainless steel in saline/plasma mixtures. Polished, annealed, cleaned and passivated 316L electrodes with a surface area/body fluid volume (SA/BFV) ratio of 23X were driven anodically in a 100 ml acid cleaned cell at 950 and 1150 mV (vs. SCE). Electrolyte solutions of isotonic saline (pH = 7.4) containing 0, 5, 10 and 25 volume percent human plasma were used. Aliquots of solution were taken at intervals and analyzed for Cr, Ni and Fe by atomic absorption spectrophotometry. Corrosion continued until a total charge of 1.0 to 1.5 C was passed. Plots of solution metal concentration versus electrolyte solution composition, calculated at an isocoulombic point (Q = 0.5 C) and adjusted for initial concentration, were prepared to test for effects of the presence of plasma proteins. Increases in elemental release rates of up to 3x (p 0.05) were found, with peak effects in 5 and 10 volume percent plasma solutions. The effects depend upon anodic potential, metal species, plasma protein concentration and possibly plasma composition.
Microstructure and Friction of Ion Beam Induced Amorphous Ti-Pd Alloys
Authors: Hirvonen J-P. , Nastasi M. , Phillips J. R. , Mayer J. W. 
Published: June 2019

ABSTRACTMultilayered samples of Ti-Pd with linearly varying compositions were irradiated by Xe ions at 600 keV. The induced microstructures were studied by using transmission electron microscopy and Rutherford backscattering. Mixing was found to be complete over the entire composition range, resulting in amorphous or amorphous plus crystalline structures except at the palladium-rich end, where a crystalline Pd-Ti solid solution was obtained. This is consistent with the high equilibrium solubility of Ti in Pd. In addition, significant coarsening of the microstructure caused by irradiation was found in this solid solution region.Friction measurements were carried out in air and water by using a polytetrafluoroethylene pin as a counterpart. In air the friction coefficient was independent of composition and microstructure after about 2000 passes. In water, however, after 600 passes the friction coefficient reached a steady-state value with a pronounced minimum over the amorphous region. This property was unchanged throughout the remaining 10000 passes.
Ftir and Resolved Esca Studies of Segmented Polyether Polyurethanes
Authors: Grobe G. L. , Gardella Joseph A. , Chin Roland L. , Salvati Lawrence 
Published: June 2019

ABSTRACTSurface analysis of biomedical materials is necessary for determination of surface structure/biological property relationships. Previous studies [3,6] have demonstrated the applicability of Angle Resolved X-Ray Photoelectron Spectroscopy (ARXPS or ARESCA) and Fourier Transform Infrared Spectroscopy (FT-IR) with Attenuated Total Reflectance (ATR) sampling. Using these surface sensitive techniques on currently marketed segmented polyurethanes (SPU) (Biomer TMand Cardiothane-51TM), we have investigated chemical and morpholgical differences between polymeric mixtures cast from solvents of varying polarity. These materials are used because of their resistance to degradation and hydrolysis.Results will show: (1) Selective casting of different constituents of the mixture as monitored by FT-IR, where polymers can be represented as opposed to block copolymers; (2) Correlation between the Hildebrand solubility parameter of the casting solvent and the portion of the polymer selectively cast; (3) Models of solution cast polymers will be presented including (concentration gradient) of the constituents; (4) SEM micrographs will provide information on domain size and the formation of these solution cast films; (5) Depths and concentration gradients will be estimated by comparing results from AHXPS and variable angle FT-IR/ATR.
Biomedical Materials to Repair Retinal Detachments
Authors: Refojo Miguel F. 
Published: June 2019

ABSTRACTImplants are essential for the repair of retinal detachments. The implant buckles the wall of the eye and apposes the detached retina with the choroid, thus restoring light sensitivity to the retina. The scleral buckling also relieves traction on the retina from a shrinking vitreous body. The implant materials most commonly used are solid silicone rubber and silicone sponges, but both types have some disadvantages. A poly(hydroxyethyl acrylate-co-methyl acrylate) hydrogel implant with improved properties of softness and antibiotic absorption is also available for retinal detachment surgery. Proliferative vitreoretinopathy involves various conditions of retinal detachment complicated by vitreous fibrosis, which, after vitrectomy, may be treated with intraocular injection of fluids that support the retina against the choroid. For conditions requiring a long-term implant, silicone oil although controversial is the material of choice. Many other substances have been investigated but none better has yet been found.
Bioactive Materials
Authors: Hench L. L. , Wilson June 
Published: June 2019

ABSTRACTBiomaterials can be classified in terms of their interfacial response with tissues: 1) nearly inert, 2) nearly inert microporous, 3) resorbable, and 4) surface active. Surface active biomaterials include bioactive glasses such as Bioglass®, bioactive glass-ceramics such as Ceravital® or A/W Glass-Ceramic, hydroxylapatite such as Calcitite® or bioactive composites such as Palavital® or stainless steel fiber reinforced Bioglass®. All of the above surface active biomaterials form an interfacial bond with adjacent tissue. However, the time dependence of bonding, strength of bond, mechanisms of bonding, and thickness of bonding zone differ. Depending upon composition, type of tissue, and type of load applied, and explanation for the compositional dependence is presented together with various medical and dental implant applications, including middle ear prostheses, maxillofacial reconstruction, endosseous ridge maintenance and augmentation, periodontal packing, and fixation of orthopedic joint prostheses.
Composite Plaster/Hydroxylapatite Implants for Jaw Bone Restoration
Authors: Hanker Jacob S. , Tucker Myron R. , Terry Bill C. , Carnevale Reynolds A. , Giammara Beverly L. 
Published: June 2019

ABSTRACTSintered ceramic, nonresorbable hydroxylapatite (HA) is a calcium phosphate biomaterial widely employed alone for augmentation or maintenance of the mandibular ridge and for filling alveolar bony defects. The small particles used for ridge augmentation or periodontal defects tend to scatter and the larger blocks used for extraction sockets don't fit well. Our recent studies suggest that these problems can be circumvented by composite plaster of Paris/HA implants. In addition to binding the HA particles, the plaster makes the implants easier to shape. Plaster is not only very biocompatible but may actually help prevent infection. It appears to act as a scaffold for incorporation of the HA particles into osseous tissue. In several days the plaster is resorbed but it is replaced at the same rate by infiltrating fibrovascular tissue; plaster definitely promotes the filling of osseous defects initially by connective tissue. This tissue not only maintains the form and integrity of the implant, but its vascular and collagen components promote healing and contribute to subsequent filling of the defects and approximation of the HA particles by new cancellous bone. These composite implants can be preformed on casts prior to surgery or tailored during the surgical procedure. Their use precludes the difficulties encountered when plaster alone is implanted (resorption) or when HA alone is used (particle scatter or nonpenetration of the material by host vascular and connective tissues). By having a resorbable component which permits penetration by fibrovascular tissue and a nonresorbable component which can act as a nidus for new cancellous bone formation, these composite alloplasts act like artificial bone. Their use to support a denture, or for immobilizing teeth and reducing pocket depths in advanced periodontal disease, gives better results than HA alone.
The Use of the Four-Point Bending Technique for Determining the Strength of Low K Dielectric/Barrier Interface
Authors: Tsui Ting , Goldberg Cindy , Braeckelman Greg , Filipiak Stan , Ekstrom Bradley M. , Lee J.J. , Jackson Eric , Herrick Matthew , Iacoponi John , Martin Jeremy , Sieloff David 
Published: June 2019

AbstractOne of the important reliability challenges in integrating copper/Low-K dielectric technology has been adhesion between the Low-K dielectric and barrier metal. This investigation explored the applicability of the four-point bend technique for determining the adhesion strength of a fluorine doped low dielectric constant oxide in contact with tantalum barrier layer. Time of flight secondary ion mass spectroscopy (ToFSIMS) was used for surface chemical analyses of the delaminated surfaces to identify the fractured interface and its chemical compositions. The effect of annealing on mechanical strength was coupled with chemical analysis to discern the adhesion properties. Experimental results suggested that fluorine rich interfacial layer formation was associated with degraded adhesion characteristics between Low-K dielectric and tantalum barrier metal.
Microtexture and Strain in Electroplated Copper Interconnects
Authors: Spolenak R. , Barr D. L. , Gross M. E. , Evans-Lutterodt K. , Brown W. L. , Tamura N. , Macdowell A. A. , Celestre R. S. , Padmore H. A. , Valek B. C. , Bravman J. C. , Flinn P. , Marieb T. , Keller R. R. , Batterman B. W. , Patel J. R. 
Published: June 2019

AbstractThe microstructure of narrow metal conductors in the electrical interconnections on IC chips has often been identified as of major importance in the reliability of these devices. The stresses and stress gradients that develop in the conductors as a result of thermal expansion differences in the materials and of electromigration at high current densities are believed to be strongly dependent on the details of the grain structure. The present work discusses new techniques based on microbeam x-ray diffraction (MBXRD) that have enabled measurement not only of the microstructure of totally encapsulated conductors but also of the local stresses in them on a micron and submicron scale. White x-rays from the Advanced Light Source were focused to a micron spot size by Kirkpatrick-Baez mirrors. The sample was stepped under the micro-beam and Laue images obtained at each sample location using a CCD area detector. Microstructure and local strain were deduced from these images. Cu lines with widths ranging from 0.8 [.proportional]m to 5 [.proportional]m and thickness of 1 [.proportional]m were investigated. Comparisons are made between the capabilities of MBXRD and the well established techniques of broad beam XRD, electron back scatter diffraction (EBSD) and focused ion beam imagining (FIB).