bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermomechanical Fatigue Behavior of an Aluminide-Coated Monocrystalline Ni-Base Superalloy
Authors: Grube F , Affeldt EE , Mughrabi H 
Published: April 2008

This study is part of a project concerned with the effect of diffusional aluminide coatings on the stress response and life of a coated monocrystalline nickel-base superalloy (CMSX-6) during thermomechanical fatigue (TMF) testing.
In this project, the effects of different platinum-modified aluminide coatings are studied. To separate the effects induced by the coatings from other effects with respect to the TMF life, uncoated specimens are investigated as reference specimens.
In this paper, TMF studies on specimens coated with a two-phase platinum-modified aluminide coating are reported. The TMF tests were performed with a particular type of asymmetric counterclockwise diamond cycle (lower and upper temperatures: 400 °C and 1100 °C, respectively) representing typical loads experienced by turbine blades under conditions of service during start-up and shut-down operation. The life of the specimen is determined by crack initiation and propagation. Crack initiation is observed to occur early during TMF life at the surface of the coating as a consequence of its brittleness at low temperatures. Thus, the coating shortens the life of the substrate-coating system. In this context, the characteristics of the two-phase platinum-aluminide coating studied here and its influence on the mechanisms of crack initiation and propagation during TMF are of special interest.
Analysis of Thermal Gradients during Cyclic Thermal Loading under High Heating Rates
Authors: Affeldt EE , Hammer J , Huber U , Lundblad H 
Published: April 2008

The magnitude of temperature gradients and their variation with temperature and time was investigated for a thermomechanical fatigue (TMF) cycle between 400°C and 1100°C under a heating rate of 10°C/s. The measurements of the temperature distribution in the gauge section of a flat rectangular specimen of the Nickel base superalloy CMSX-6 were carried out by means of thermocouples located at various positions on the surface and in the volume, respectively. As a reference the temperature distribution was calculated by finite element analysis based on the temperature signal of the control thermocouple. Additionally, the surface temperature distribution was studied by thermographic measurements.
The results reveal that thermal gradients establish in longitudinal and in transverse direction of the gauge section. Although the temperatures in the bulk material exceed the reference given by the control signal during the entire cycle, this effect is most pronounced (+40°C) during cooling by forced air. In comparison, the predictive results of the finite element calculation lead to slightly enhanced surface temperatures during heating (+8°C) and to reduced surface temperatures during cooling (-5°C). Therefore, it is concluded that heat transport in the bulk material is sufficiently fast to guarantee almost homogeneous temperature distribution. The significantly enhanced volume temperatures in the experiment were found to result from influences of the experimental set-up, and from superimposed effects due to forced air cooling and heat flow through the wires of the spot welded thermocouple.
Thickness Effects on the Promoted Ignition-Combustion Behavior of Engineering Alloys
Authors: Samant AV , Zawierucha R , Million JF 
Published: April 2008

For several years the ASTM G-4 committee has been actively publishing ocuments pertaining to the suitability of using various engineering alloys in oxygen-enriched atmospheres. These publications have resulted in a better understanding of the behavior of materials and have helped industry-wide consciousness of the safety and ntegrity requirements of equipment utilized in the generation, transportation and use of oxygen. However, the majority of promoted ignition-combustion data are based on testing conducted on 3.2-mm-diameter specimens and data on other specimen geometries are limited.
In practice, oxygen systems often use materials in a variety of thicknesses. Hence, here is a need for determining the suitability of using materials of cross sections other than 3.2 mm to represent the various components typically encountered in such systems.
This paper is dedicated to the discussion of thickness effects on the promoted ignition-combustion behavior of a few commonly used austenitic alloys in oxygen-enriched atmospheres. Effects of oxygen gas pressure and material thickness on the combustion behavior of the alloys tested will be discussed.
A Database for Performing and Archiving Oxygen Hazards Analyses
Authors: Peralta SF , Stoltzfus JM 
Published: April 2008

ASTM Committee G-04 published several guides and a manual that outline a process for identifying and analyzing fire hazards in oxygen systems. Many companies and government agencies have accepted this process and require hazards analyses to be performed on oxygen systems. When an oxygen hazards analysis is performed, the results are usually documented to identify the hazards associated with the system and its components.
The information needed to perform an oxygen hazards analysis include details on system components, configuration, and operating conditions. Material flammability, ignitability, and potential damage data are also used when analyzing oxygen hazards. In the past, word processing and spreadsheet tools have been used to document results. However, the wide variety of numerical data, explanatory text, and pictures or graphics makes it difficult to retrievably catalog hazards data using word processing and spreadsheet tools.
Recently, the NASA White Sands Test Facility (WSTF) was requested to do an increased number of oxygen hazards analyses. In doing so, it became apparent that many oxygen systems use the same components with slight variations. However, with the existing tools, all data had to be re-entered for each analysis. To increase efficiency and precision of analysis, an electronic database for performing oxygen hazards analyses was developed.
The database provides a repository of all information used in hazards analyses, including drawings, materials data, and environmental information that can be used for future analyses. Furthermore, the analyses of both systems and components remain available for future reference, allowing users to quickly access all data and past analyses as a reference for performing current analyses and answering questions that arise during the process. This paper presents the design, layout, advantages, and potential uses of this database.
A Parametric Modeling Study of the Temperature Dynamics of Contaminated or Damaged Softgoods in Compressed Oxygen
Authors: Wilson DB , Barragan M , Beeson HD 
Published: April 2008

The continuing occurrence of fires in systems processing oxidizing gases necessitates further analysis into likely causes. Oil contamination and damaged softgoods have been identified as burning components, while adiabatic compression and particle impact have been identified as ignition sources. This work reports experimental observations on a simulated primary pressure control module in the presence of oil contamination under repeated compression of oxygen. This system is mathematically modeled and studied for the effects of parameter variation. Model parameters are ullage volume, pressure ratio, oil film thickness, softgoods thickness, drop size, and heat transfer. Model analysis is validated by the experimental results.
A generic, lumped parameter heat transfer model of combinations of oil film, softgoods, and metal heat transfer surfaces is developed. This model allows for consideration of damaged softgoods under these previous conditions, and demonstrates the greater susceptibility for fires such a system presents.
Epidemiology of NCAA Men's Ice Hockey Injuries
Authors: LaPrade RF , Dick RN , Kiff TA , Wentorf FA 
Published: April 2008

The purpose of this project was to demonstrate the epidemiology of NCAA ice hockey injuries and to determine any trends in injury occurrence.
The NCAA injury surveillance system for men's intercollegiate ice hockey, which as been prospectively collected in Divisions I, II, and III since the 1986–87 season, was reviewed. Injury rates were expressed as injuries per 1000 athlete exposures (A/E). Practice injury rates in Division I were 2.1/1000 A/E and for Division III were 2.5/1000 A/E from 1986–87 to 2000–01. The game injury rates for both divisions were the same at 17.5/1000 A/E. The rest of the injury data were collated among all three divisions for injury timing (preseason or regular season), injuries requiring surgery, and body part injured.
In conclusion, men's NCAA ice hockey has a low incidence of practice injuries with the highest incidence of these injuries occurring in the preseason. It also has a low rate of surgery compared with all other sports and has a higher than average incidence of injury in games. While shoulder and knee injuries have the highest incidence over time, the incidence of reported concussions has been increasing since 1986–87.
Measuring the Effects of Initiating Body Checking at the Atom Age Level
Authors: Montelpare WJ , McPherson MN 
Published: April 2008

The purpose of this study was to determine the effects of initiating body checking at the Atom age level. The study used an experimental design in which teams from the Ottawa District Minor Hockey Association (ODMHA) represented the control group, while teams from the Ontario Hockey Federation (OHF) represented the treatment group. The study was conducted over a three-year period from 1998 to 2001. The comparison sampling between the two leagues was as follows: ODMHA Yr1 = 69 teams versus OHF Yr1 = 74 teams, ODMHA Yr2 = 59 teams versus OHF Yr2 = 101 teams, ODMHA Yr3 = 46 teams versus OHF Yr3 = 90 teams. Measures of interest reported here included player selection bias, injury incidence, and variables that describe the characteristics of the flow of the game such as goals for, goals against, and number of penalties. Athlete exposures for each league by year were computed using 15 players per team for a 20 game plus 20 practice schedule.
Statistical analysis of the difference in proportions of injuries reported by the two leagues based on the CHA injury insurance dataset showed that no significant difference occurred per year of the study. In addition, the rates of injuries were lower in each year than those reported by previously published studies.
Body checking, which includes body contact is considered by many to be a skill within the game of ice hockey that can be taught at the younger age levels in a manner that does not lead to a higher incidence of injuries, or unfavorable changes in the game. The results of this study support that contention. In the present study, it was assumed that education was an essential component of the introduction process and that coaches were provided the necessary background to enable them to teach the introduction of body checking as a skill.
Measurement of Pore Size and Porosity of Tissue Scaffolds
Authors: Tomlins P , Grant P , Mikhalovsky S , James S , Mikhalovska L 
Published: April 2008

Tissue engineering involves seeding the patient's cells on to a three dimensional temporary scaffold. It is becoming increasingly obvious that cells used to seed the scaffold have very specific requirements concerning the morphology and chemistry of the surface of the scaffold and its interconnectivity. A range of techniques has been examined in relation to key measurements such as pore size and porosity. Since capillary flow porometry measures a pore solely at its most constricted point, the method is unable to provide characterisation of other aspects of the pore.
Scanning Electron Microscopy is limited to examining surface pores in ‘stiff’ scaffolds. Although cryo-SEM reduces the amount of ice-induced damage generated in ‘soft’ scaffolds upon freezing, the technique is limited to the same constraints. Imagesproduced via scanning confocal microscopy are probably more representative of the truestructure of the scaffold than that implied by cryo-SEM, although due to the diffuse nature of the image it is difficult to measure pore sizes.
Microbiological Safety and Adventitious Agents Standards for TEMPS
Authors: Sofer G 
Published: April 2008

Microbiological contamination and adventitious virus contamination can be introduced into TEMPs from source materials, such as cells, cell culture media, scaffolds, and growth factors. Contamination can occur during isolation and expansion of cells, production of scaffolds and growth factors, and product manufacturing. Contamination may also arise during storage due to the inability to use sufficiently stringent preservation and storage methods without destroying the TEMPs' function.
Standard safety testing for pathogens may not be suitable for TEMPs. New rapid microbiological detection methods and PCR assays for mycoplasma and virus may enable preliminary product release. Cleaning and sanitization of equipment can be validated using a combination of traditional and new, more rapid methods. When there are significant processing steps, clearance studies can provide a further assurance of freedom from unwanted adventitious agents.
The European Situation on Standards for Tissue Engineering Products
Authors: Schutte E 
Published: April 2008

Human tissue engineered medical products are not regulated on a European level. This means that, to date, various national approaches exist to regulation of Tissue Engineered Products in Europe. In general, diversity exists how these products should be regulated. Some Member States wait for the European Commission to take a position and fill in the gap of regulation. Other countries develop specific regulation on human tissue products, and use elements on tissue banking principles; other countries use the pharmaceutical approach, whereas others use the medical device regulation as a basis.
The industry favors a new regime based on a risk/benefit based approach. The Directive should define essential requirements, and to demonstrate compliance to these requirements, harmonized standards should be used.
Recently, some new initiatives have started, concerning future harmonized European regulation, such as the draft Directive as “Setting high standards of quality and safety for the procurement, testing, processing, storage and distribution of human tissues and cells”, in order to ensure a high level of human health protection. At the same time the European Commission solicited input for a framework to solve free trade amongst Member States.
Microscopy of Highly Cross-Linked UHMWPE Wear Surfaces
Authors: Rieker CB , Konrad R , Schön R , Schneider W , Abt NA 
Published: April 2008

Highly cross-linked ultra high molecular weight polyethylenes (UHMWPEs) were developed to reduce UHMWPE wear in arthroplasty. These UHMWPEs have manifested a significant improvement in the in-vitro adhesive — abrasive wear resistance of total joint prostheses.
Examination of the first clinically retrieved liners revealed surface features not usually observed on previous retrievals. A flattening of the machining marks is evident, together with the presence of ripples with micro-fissures. To evaluate these features, examinations were performed on a cup-on-ball device, an AMTI hip simulator, and a Stanmore knee simulator, as well as on retrieved components with a maximum follow-up of 15 months. The surface features of the components were investigated with light microscopy, by scanning electron microscopy (SEM), and also by transmission electron microscopy (TEM).
Ripples with micro-fissures were observed on the loaded areas perpendicular to the principal directions of motion. The transverse examinations of all sections of these specimens, which were made with optical microscopy and by TEM, showed that the ripples with micro-fissures may be described as folds. With all the investigated samples, the depth of the micro-cracks at the tip of the folds extended to a maximum of 5 μm below the surface. The folds experienced with UHMWPE were already described in the late 1970s.
Due to the extreme wear resistance of highly cross-linked UHMWPEs, these folds accumulate on the surface of components manufactured in this new generation of UHMWPEs. In view of their depth stability with the number of cycles, we believe that these folds have no influence on the fatigue behavior of such components.
Improved Resistance to Wear, Delamination and Posterior Loading Fatigue Damage of Electron Beam Irradiated, Melt-Annealed, Highly Crosslinked UHMWPE Knee Inserts
Authors: Yao JQ , Blanchard CR , Lu X , Laurent MP , Johnson TS , Gilbertson LN , Swarts DF , Crowninshield RD 
Published: April 2008

Recently, a knee prosthesis containing an electron beam irradiated (58 – 72 kGy, nominal dose of 65 kGy), melt-annealed, highly crosslinked UHMWPE (HXPE) tibial insert has been developed. In the present study, the wear and delamination resistance of the HXPE tibial insert and its fatigue performance under a posterior loading condition have been evaluated against its conventional gamma-sterilized UHMWPE counterpart (37kGy, in nitrogen). The test methodologies used were newly developed with the aim to evaluate this new material under severe testing conditions.
In comparison to the gamma controls, the HXPE inserts: (a) wore significantly less (achieving wear reductions of 81% and 73% over 5 and 20 million cycles, respectively); (b) exhibited significantly improved delamination resistance; and (c) exhibited significantly improved posterior loading fatigue resistance.
Characterization of the Wear Performance of Crosslinked UHMWPE and Relationship to Molding Procedures
Authors: St.John KR , Poggie RA 
Published: April 2008

Using an eight-station hip wear simulator, radiation-crosslinked polyethylenes were tested for their resistance to wear-related weight loss and the results compared to results for studies conducted on the same machine using polyethylene that was being implanted at the time. The testing results showed that the wear rate of crosslinked (60 kGy) Slab Compression Molded (SCM) polymer was about 63% lower than standard (30 kGy) SCM cups and 69% less than Ram Extruded 4150 (30 kGy) cups. The Near-net Final Shape molded (NFS) crosslinked (60 kGy) specimens had an 89% reduction in wear rate over the standard (30 kGy) NFS cups, regardless of whether GUR 1020 or GUR 1050 crosslinked cups were tested. All wear rates for nitrogen packaged materials were significantly superior to those for cups sterilized in air and for earlier generation GUR 4150 products sterilized and stored in contact with oxygen.
The results confirm that both the SCM and NFS molding processes produce acetabular cups with excellent wear properties as compared to previous processes. The additional crosslinking process, described herein, provided a major improvement in the wear resistance with either molding process with greater improvement occurring in the NFS specimens.
Influence of Electron Beam Irradiation Dose on the Properties of Crosslinked UHMWPE
Authors: Abt NA , Schneider W , Schön R , Rieker CB 
Published: April 2008

The purpose of this study was to investigate the influence of a dose of e-beam irradiation on the mechanical and tribological properties of crosslinked UHMWPE.
Specimens of UHMWPE were irradiated at different dose levels between 0 and 110 kGy using the WIAM e-beam process. Irradiation was followed by melt annealing and slow cooling.
In general, the mechanical properties of irradiated UHMWPE decrease with increasing irradiation dose. Increasing the irradiation dose from 50 to 95 kGy results in a loss of 4% yield strength, 16% elongation, 15% tensile strength and 18% impact strength. Crystallinity does not change significantly.
In comparison with conventional material, irradiation with 50 kGy reduces the wear rate by 73%. A further reduction of 56% can be realized by increasing the dose from 50 to 95 kGy.
Elevated Crosslinking Alone Does Not Explain Polyethylene Wear Resistance
Authors: Furman BD , Maher SA , Morgan TG , Wright TM 
Published: April 2008

New ultra high molecular weight polyethylene (UHMWPE) materials have been introduced that utilize elevated radiation doses combined with post-irradiation heat treatments. The elevated radiation dose creates higher levels of crosslinking and is reported to cause improved abrasive wear resistance. The heat treatment quenches free radicals that result from irradiation, thus preventing oxidative degradation. Although abrasive wear occurs between conforming bearing surfaces, macroscopic wear damage is more commonly cited than abrasive wear as a limiting factor with non-conforming surfaces such as occur in knee replacements. Though these new materials demonstrate reduced mechanical properties compared to conventional UHMWPE gamma irradiated in air, recent studies revealed that some of these materials performed well under non-conforming in vitro wear conditions. Our aim was to understand why materials with reduced fracture toughness and yield strength would be more resistant to wear damage.
Polyethylene materials with varying radiation doses and heat treatments were examined. We compared modulus, yield strength, ultimate stress, and ductility, J-integral fracture toughness, density and wear. Crystalline morphology was evaluated using transmission electron microscopy. A relation was found between modulus, morphology and wear behavior. Materials with modulus equal to or less than 850 MPa and the majority of lamellae measuring less than 200 nm demonstrated no pitting, delamination or cracking in wear tests, regardless of the level of crosslinking. Even though elevated crosslinked materials showed reduced toughness, they demonstrated good damage resistance, but elevated crosslinking alone does not explain wear damage resistance.
Integrating Mineral Development and Biodiversity Conservation into Regional Land-Use Planning
Authors: Richards DG 
Published: April 2008

A major independent multi-stakeholder analysis of how the mining industry can maximize its role in the transition to sustainable patterns of development — the Mining, Minerals and Sustainable Development (MMSD) project — concluded in 2001. Prominent among the recommendations in the MMSD report were the need for the mining industry to improve its performance in biodiversity assessment and management, and the need for all parties to commit to better models for decision-making processes in land use and access.
Mining is a temporary use of land, but history teaches us that the net effect of mining in a landscape is usually negative for biodiversity. There are benefits to human society in health, wealth and education, but society increasingly demands that environmental values be protected without compromising economic and social foundations. These expectations are captured in the concept of sustainable development.
Often, the most prospective areas for future mines will also be those with the greatest biodiversity value and with the greatest need for poverty alleviation. Many governments lack the capacity, will or resources to reconcile these conflicting needs equitably. Corruption in government and oppression of local populations have accompanied some mine developments.
Leading companies in the mining industry believe that these negative experiences are not inevitable, that better decisions on land use and access can be achieved and that sustainable benefits can be delivered through mineral development. One key to achieving these outcomes is the regional landscape-scale analysis of projects and conservation priorities, supported by fair, transparent and consistent decisionmaking processes.
Rio Tinto is a large diversified mining company which played a leading role in the actions leading to the commissioning of the MMSD project and participated fully in it. Examples from recent projects in Rio Tinto, illustrating aspects of regional planning and conservation actions, are presented in support of the case outlined above.