bluuebunny/crossref_metadata_2025 huggingface dataset:
Are Coronary Angiograms of Value in the Risk Stratification of Patients Undergoing Coronary Artery Bypass Surgery?
Authors: Lawrence David R , Somaskanthan Rajael , Barnard Matthew J , Curtis Miles , Keogh Bruce E
Published: May 2009

INTRODUCTION

There are currently more than 20 risk-scoring systems that attempt to predict peri-operative mortality following coronary artery bypass surgery (CABG). All these scoring systems use objective criteria to assess operative risk. Angiographic data are currently not included in any of these systems. This pilot study assessed the value of coronary angiography in predicting peri-operative mortality following CABG.

PATIENTS AND METHODS

Fourteen patients who died following first-time isolated CABG surgery were identified. These were matched with 14 patients of similar age, sex, left ventricle function and European System for Cardiac Operative Risk Evaluation (EuroSCORE). A panel of 25 clinicians were given details of the patients' age, sex, diabetic status, family history, smoking history, hypertensive status, lipid status, pre-operative symptoms, left ventricle ejection fraction and weight and shown the coronary angiograms of the patient. They were asked to predict the outcome following CABG for each patient.

RESULTS

Receiver operator characteristic curves were constructed and the area under the curves calculated and analysed using a commercially available statistical package (PRISM). The area under the curve for the group was 0.6820 for the group. Consultant clinicians achieved an area of 0.6789 versus their trainees 0.6844 (P = NS). The cardiologists achieved an area of 0.7063 versus the cardiothoracic surgeons 0.6491 (P = NS).

CONCLUSIONS

Despite the EuroSCORE predicting equal risk for the two groups of patients, it would appear that clinicians are able to identify individual higher risk patients by assessing pre-operatively the quality of the patient' coronary vasculature. Although the clinicians were able to predict individual patient mortality better than the EuroSCORE, the area under the curve indicates that it is not a robust method and clinicians, with all the clinical information to hand, are only moderately good at predicting the outcome following coronary artery bypass surgery.
A One-Stop Carpal Tunnel Clinic
Authors: Reid MJ , David LA , Nicholl JE
Published: May 2009

INTRODUCTION

By December 2008, 90% of referrals requiring hospital admission will need to be seen and treated within the 18-week patient pathway. Previously, patients within our trust with suspected carpal tunnel syndrome had to wait 3 months to see a specialist in clinic and, once assessed, would have to wait up to a further 6 months for an open carpal tunnel decompression under local anaesthetic (OCTD/LA). We set up a one-stop clinic, where patients would have their out-patient consultation and surgery on the same day. We evaluated the clinic in order to assess whether it led to reduced waiting times whilst maintaining good clinical outcome and patient satisfaction.

PATIENTS AND METHODS

Patients were selected on the basis of the standard referral letter alone. Those selected were then assessed by a single surgeon in the clinic. The patients deemed appropriate underwent an OCTD/LA and were discharged the same day. Patients were followed up with a patient satisfaction and Boston questionnaire.

RESULTS

Forty-six patients underwent 63 OCTD/LA, waiting an average of 2.2 months (9 weeks) from referral. There was high patient satisfaction and improvement in symptoms following treatment in the clinic.

CONCLUSIONS

We believe a one-stop carpal tunnel clinic can be an efficient and cost-effective way of treating this common condition.
Hernia Surgery: From Guidelines to Clinical Practice
Authors: Kingsnorth Andrew N
Published: May 2009

INTRODUCTION

Over the last 30 years, hernia surgery has developed into an evidence-based practice assisted by the development of guidelines.

MATERIALS AND METHODS

Prior to 1993, best practice in the UK was a nylon darn repair under general anaesthesia as an in-patient with prolonged recovery. The publication of The Royal College of Surgeons of England (RCSE) Guidelines on Groin Hernia Repair stimulated debate and coincided with the introduction of mesh hernioplasty and laparoscopic techniques. Further evolution of hernia management has occurred to enable the production of the European Hernia Society (EHS) guidelines in 2008.

RESULTS

The EHS guidelines cover all aspects of abdominal wall surgery including: indications for operation; investigations; organising surgical care; techniques; local anaesthesia; after-care, complications and outcome; and information for patients.

CONCLUSIONS

Surgeons have many choices when selecting an appropriate hernia operation for an individual patient. The EHS guidelines provide a basis for this decision-making.
Isolated Duodenal Rupture due to Go-Karting Accidents – Braking News
Authors: Thomas Milan , Basu Narendra Nath , Gulati Manpreet Singh , Oke Tayo , Constantinescu Gabriel , Siddiqui Midhat
Published: May 2009

INTRODUCTION

Isolated duodenal injury due to blunt abdominal trauma is extremely rare. We present a series of three such injuries due to go-karting accidents, which presented to our hospital over 5 months.

CASE REPORTS

Between October 2007 and February 2008, three cases of D3/D4 duodenal rupture presented to our hospital after go-karting accidents. Trauma occurred as a result of the steering wheel impacting on the abdomen. All patients presented similarly with symptoms of epigastric and right upper quadrant pain. In all cases, computed tomography scanning was highly suggestive of duodenal injury and, in particular, demonstrated presence of retroperitoneal air centred around the duodenum. Treatment required laparotomy and operative repair in all cases.

CONCLUSIONS

Duodenal injury presents insidiously due to its retroperitoneal position. A low threshold for investigating patients presenting with epigastric and right upper quadrant pain should be adopted along with active clinical vigilance to exclude serious and life-threatening trauma after go-karting accidents.
Implications for Pharmacy from the Institute of Medicine's Report on Health Care Workforce and an Aging America
Authors: Gray Shelly L , Elliott David , Semla Todd
Published: May 2009

The Institute of Medicine's report “Retooling for an Aging America: Building the Health Care Workforce” concluded that the US health care workforce will require significant overhaul to care for the estimated 70 million adults 65 years and older by 2030. No profession trains the numbers of geriatric specialists needed to maintain the current provider to patient ratio. Pharmacy is no exception; currently less than 1% of pharmacists are certified or have specialty training in geriatrics. Schools of pharmacy, accrediting and professional organizations, and boards of pharmacy will need to collaborate to ensure that pharmacists have the core competencies to care for older adults.
PGE2 Signaling Through the EP4 Receptor on Fibroblasts Upregulates RANKL and Stimulates Osteolysis
Authors: Tsutsumi Ryosuke , Xie Chao , Wei Xiaochao , Zhang Minjie , Zhang Xinping , Flick Lisa M , Schwarz Edward M , O'Keefe Regis J
Published: May 2009

Periprosthetic osteolysis is the most common cause of aseptic loosening in total joint arthroplasty. The role of inflammatory mediators such as prostaglandin E2 (PGE2) and osteoclast promoting factors including RANKL in the pathogenesis of osteolysis has been well characterized. However, the PGE2 receptor (EP1, EP2, or EP4), and cell type in which it is expressed, which is responsible for PGE2 induction of RANKL during wear debris–induced osteolysis, has yet to be elucidated. To address this, we used mice genetically deficient in these EP receptors to assess PGE2 and wear debris responses in vitro and in vivo. Wear debris–induced osteolysis and RANKL expression were observed at similar levels in WT, EP1−/−, and EP2−/− mice, indicating that these receptors do not mediate PGE2 signals in this process. A conditional knockout approach was used to eliminate EP4 expression in FSP1+ fibroblasts that are the predominant source of RANKL. In the absence of EP4, fibroblasts do not express RANKL after stimulation with particles or PGE2, nor do they exhibit high levels of osteoclasts and osteolysis. These results show that periprosthetic fibroblasts are important mediators of osteolysis through the expression of RANKL, which is induced after PGE2 signaling through the EP4 receptor.
Intermittent PTH Administration Stimulates Pre-Osteoblastic Proliferation Without Leading to Enhanced Bone Formation in Osteoclast-Less c-fos−/− Mice
Authors: de Freitas Paulo Henrique Luiz , Li Minqi , Ninomiya Tadashi , Nakamura Midori , Ubaidus Sobhan , Oda Kimimitsu , Udagawa Nobuyuki , Maeda Takeyasu , Takagi Ritsuo , Amizuka Norio
Published: May 2009

This study aimed to investigate the behavior and ultrastructure of osteoblastic cells after intermittent PTH treatment and attempted to elucidate the role of osteoclasts on the mediation of PTH-driven bone anabolism. After administering PTH intermittently to wildtype and c-fos−/− mice, immunohistochemical, histomorphometrical, ultrastructural, and statistical examinations were performed. Structural and kinetic parameters related to bone formation were increased in PTH-treated wildtype mice, whereas in the osteoclast-deficient c-fos−/− mice, there were no significant differences between groups. In wildtype and knockout mice, PTH administration led to significant increases in the number of cells double-positive for alkaline phosphatase and BrdU, suggesting active pre-osteoblastic proliferation. Ultrastructural examinations showed two major pre-osteoblastic subtypes: one rich in endoplasmic reticulum (ER), the hypER cell, and other with fewer and dispersed ER, the misER cell. The latter constituted the most abundant preosteoblastic phenotype after PTH administration in the wildtype mice. In c-fos−/− mice, misER cells were present on the bone surfaces but did not seem to be actively producing bone matrix. Several misER cells were shown to be positive for EphB4 and were eventually seen rather close to osteoclasts in the PTH-administered wildtype mice. We concluded that the absence of osteoclasts in c-fos−/− mice might hinder PTH-driven bone anabolism and that osteoclastic presence may be necessary for full osteoblastic differentiation and enhanced bone formation seen after intermittent PTH administration.
Loss of Hip BMD in Older Men: The Osteoporotic Fractures in Men (MrOS) Study
Authors: Cawthon Peggy M , Ewing Susan K , McCulloch Charles E , Ensrud Kristine E , Cauley Jane A , Cummings Steven R , Orwoll Eric S
Published: May 2009

Previous studies in older men have not evaluated whether loss of BMD or BMC accelerates nonlinearly with age. This study aimed to describe hip bone loss (both in BMC and BMD) in older men and to test whether BMD loss accelerates with age in an exponential manner in a cohort of 4720 community-dwelling men ≥65 yr of age. Men had two to three measures of femoral neck (FN) BMD (by DXA) over an average follow-up of 4.6 yr. Change in BMD during follow-up was estimated from mixed effects regression models; the significance of a quadratic term for age was evaluated. Mean FN BMD loss was 0.013 g/cm2 (−1.72%) during follow-up. The quadratic term for age was significant, and the model showed that bone loss accelerated with age. Estimated loss of FN BMD over follow-up for men 85 yr of age (0.021 g/cm2) was 2.5 times greater than the loss expected for men 65 yr of age (0.008 g/cm2); such bone loss in 85-yr-old men may be sufficient to increase the risk of hip fracture by 25% (HR per 0.021 g/cm2 cross-sectional decrease in FN BMD: 1.25; 95% CI: 1.18–1.31) over 4.6 yr. Men with lower BMD at baseline lost the most BMD over follow-up. Although average bone loss over time is modest in older men, there is considerable variability in rate of loss. Older men and those with lower BMD lose bone more rapidly, offering potential explanation for the increasing risk of fracture with advancing age.
Effect of Penetrator Size on Dynamic Failure Response of Woven Graphite Epoxy Composites around the Critical Perforation Energy
Authors: Ojo O. B. , Wosu S. N. , Slaughter W. , Onipede O. O.
Published: May 2009

Dynamic tests were carried out on plain weave carbon epoxy composite plates of different thicknesses, namely, 12, 16, and 24 layers (0.21mm∕layer) using a Penetrating Split Hopkinson Pressure Bar (P-SHPB). Protruding spherical penetrators of different sizes (3/16, 7/32 and 1/4-in.) were used to determine the perforation threshold energies for each woven specimen. The specimen damage thresholds considered in this paper are: below perforation limit (BPL), at perforation limit (PL), and above perforation limit (APL). Perforation limits (energy that must be exceeded to perforate or completely penetrate the specimen) were experimentally determined using P-SHPB. The results show that sample thickness and penetrator size play significant roles in the nature or extent of damage. The results also show that strain rate depends on both the striker impact energy, penetrator size, and the target thickness. Cracks were found to propagate faster in thin specimens in all the damage thresholds.
FDA Recommendations for Nitinol Stent and Endovascular Graft Fatigue Characterization and Fracture Reporting
Authors: Cavanaugh KJ , Holt VM , Goode JL , Anderson E
Published: May 2009

Intravascular stents and endovascular stent-grafts provide a minimally invasive option for treating vascular disease and injury. Medical device manufacturers typically conduct radial pulsatile fatigue testing of intravascular stents and endovascular grafts to demonstrate that these devices will maintain their durability for ten years of implant life. While they are useful indicators of device performance, these test regimens do not always predict device durability in the clinical setting with perfect accuracy. In this paper, we address some of the common issues that should be considered in the design of fatigue tests, including appropriate sample sizes for fatigue testing, sample selection, loading conditions, and test setup issues. We also discuss finite element analysis of long-term cyclic fatigue. In addition, we describe appropriate methods for reporting the incidence of stent fractures after implantation. Our goals are to assist manufacturers and test laboratories in refining their in vitro fatigue testing methods to allow more accurate prediction of clinical device fractures, and to maximize the amount of useful data contained in clinical fracture reports.
A Comparison of Flexural Performance for Third-Point Loaded and Centrally-Loaded Fiber-Reinforced Concrete Beams
Authors: Bernard E. S. , Xu G. G.
Published: May 2009

Flexural performance data obtained from beams are used widely in the design of fiber-reinforced concrete (FRC) structures. However, loading configurations under which a material is expected to perform in situ seldom match the third-point loaded beam used in tests on FRC. In the present investigation, the performance of FRC beams tested using third-point loading have been compared with nominally identical beams tested using central point loading. The results indicate that the Modulus of Rupture obtained using third-point loaded beams is lower than that obtained using centrally-loaded beams but that the post-crack performance of the former is greater.
Modern Turbine Oil Oxidation Performance Limits—Meeting and Measuring Them—A Shell Perspective
Authors: Smith Peter W. R.
Published: May 2009

This paper outlines some of the significant changes in turbine oil oxidative stability requirements over the past five to ten years, and illustrates how these have been met using mineral oil-based products with differing antioxidant systems. It also considers possible future requirements and how these may be met. Use of a modified Federal Test Method 5308, and ASTM tests D 2272, D 4310, and D 943 in formulating new turbine oils and evaluating their oxidative stability is also described and contrasted. An example of oil condition monitoring on a used turbine oil from the field to assess its oxidative degradation is also given.
Utilization of Dempster-Shafer Theory of Evidence in Unsupervised Image Segmentation
Authors: Zribi M. , Rekik A. , Benjelloun M.
Published: May 2009

In this paper, we propose a new method based on the Dempster-Shafer theory of evidence for unsupervised image segmentation. This theory turns out to be quite efficient in classification of multisensor information. The application of the evidence theory in fusing information coming from different sources still poses certain problems. Of paramount importance is the problem of estimating the belief functions. Due to the coherence of this theory with the Bayesian approach, a parametric algorithm to estimate these functions based on the maximum likelihood method can be realized to estimate these belief functions. The proposed method is validated by experiments on both synthetic and real images. The experimental results show the interest of the algorithm and its potential.
New Solvents for Agriculture—A Theoretical Modeling Approach
Authors: Zhang Lei
Published: May 2009

Due to increasing environmental and regulatory concerns, many traditional solvents used in agricultural applications are currently under scrutiny. The agricultural industry needs to find alternative solvents that are environmentally friendly while continuing to deliver traditional solvent performance. A theoretical approach based on Hansen solubility parameters is described to screen potential new solvents using molecular modeling. In order to correlate theoretical data, experimental solubility data was developed for a number of agro active ingredients representing several different chemical classes. Experimental data results partially supported the theoretical approach used in this study. A trend was observed that can be used to select potential new solvents. A number of lead candidates were defined for further investigation.
Water Dispersible Granule Formulations Containing a New Defoaming Agent
Authors: Kirby Andrew F. , Lavranos Alice L. , Elsik Curtis M.
Published: May 2009

A common problem found when water dispersible granule (WG) formulations are dispersed in water is the generation of high levels of a persistent foam layer. This high level of foaming causes many difficulties for the users of WG products in agricultural sprays. The development of foam may cause spillage and loss of product as well as cause problems for tank mixing with other products. There is also a risk of uneven coverage of a spray solution containing foam, and the time taken for foam to subside can be inconvenient as well as lead to a risk of sedimentation of the suspended solid. The persistent foam problem in WG formulations is a direct consequence of the presence of a surfactant wetting agent (wetter) which is used in the formulation to aid immersion and dispersion of the granule in water and to help evenly distribute water throughout the powder matrix during manufacture of the formulation. Various approaches have been tried to overcome persistent foam in WG formulations in the past. These approaches include the use of tank-added defoaming agents, the inclusion of silicone and other common defoamer types in the formulation, and use of lower foaming wetters which are generally nonionic surfactants. These approaches have generally met with limited success or led to other difficulties. In many cases using enough of these defoaming additives to be effective in defoaming leads to reduced dispersion properties. One class of defoaming agent commonly used in WG formulations is the salts of long chain fatty acids, or soaps. These are, however, only moderately effective. It has now been found that the combination of fatty acid salts together with chelating agents and a polyacid polymer leads to greatly enhanced foam reduction. This improvement in defoaming comes with no additional loss of dispersion performance of the WG. The optimized defoaming blend is effective in WG formulations at a use rate of around 2 % by weight and can be used with all the commonly used types of surfactant wetting agents and dispersants in a wide range of active ingredients.
Effect of Geometry on the Melting Rates of Iron Rods Burning in High Pressure Oxygen
Authors: Suvorovs Terese , Ward Nicholas R. , Steinberg Theodore A. , Wilson Richard
Published: May 2009

The effect of sample geometry on the melting rates of burning iron rods was assessed. Promoted-ignition tests were conducted with rods having cylindrical, rectangular, and triangular cross-sectional shapes over a range of cross-sectional areas. The regression rate of the melting interface (RRMI) was assessed using a statistical approach which enabled the quantification of confidence levels for the observed differences in RRMI. Statistically significant differences in RRMI were observed for rods with the same cross-sectional area but different cross-sectional shape. The magnitude of the proportional difference in RRMI increased with the cross-sectional area. Triangular rods had the highest RRMI, followed by rectangular rods, and then cylindrical rods. The dependence of RRMI on rod shape is shown to relate to the action of molten metal at corners. The corners of the rectangular and triangular rods melted faster than the faces due to their locally higher surface area to volume ratios. This phenomenon altered the attachment geometry between liquid and solid phases, increasing the surface area available for heat transfer, causing faster melting. Findings relating to the application of standard flammability test results in industrial situations are also presented.
BRE Environmental Profiles: Past, Present, and Future
Authors: Steele K. , Anderson J.
Published: May 2009

Environmental conservation and the impact that the construction industry has on the environment have risen to the fore as a principle against which materials, products, specifications, and whole building fabric must be considered. The reasoning for this is sound, with the industry being responsible for the manufacture and use of hundreds of millions of tons of materials annually. At a national level in the UK alone the construction products sector is responsible for around 10 % [DEFRA statistics, 2000] of all carbon emissions. Against this background, the sector is remarkably well placed to build from work already done to develop standardized Life Cycle Assessment (LCA) approaches and to apply them to construction scenarios. As a result, the practice is now well established and has gained a growing momentum across all construction stakeholders, from clients to product suppliers.

This paper examines BRE’s experience in the field having originally developed an LCA approach called the “Environmental Profiles methodology” and used it to create an information database, specification tools, and a proprietary product certification scheme. The next phase of development is critical to the continuing success of these programs.
Impact Fatigue Failure Investigation of HVOF Coatings
Authors: David C. N. , Athanasiou M. A. , Anthymidis K. G. , Gotsis P. K.
Published: May 2009

Dynamic impact-wear and coating fatigue at cyclic loading conditions demonstrates a very demanding failure mode, which occurs in a number of mechanical applications and it becomes very critical when the application concerns aggressive working environments. The coating impact testing is a novel experimental technique developed to investigate the fatigue behavior of coating-substrate compounds, which was not possible with the common testing methods previously available. The objective of this study is to investigate the influence of the impact load on the fatigue strength of thermal spray high velocity oxy-fuel (HVOF) coatings. Furthermore, the overall aim of the current research is to prove the reliability of the impact testing method to assess the coating lifetime against fatigue, to interpret the coating failure modes, and thereby to explore its capability, whether this nonstandard test can be used in industrial scale as a reliable technique in the development and optimization of fatigue resistant coatings. Based on the above method the current research provides experimental results concerning the coating fracture in terms of cohesive and adhesive failure modes. The fatigue strength of the tested coatings is determined in terms of fatigue-like diagrams by means of scanning electron and white light interference microscopy, as well as by electron dispersive x-ray analysis (EDX) at discrete loads and number of loading cycles. From the conducted experiments, it was shown that the optimum HVOF coating against fatigue is the WC-CoCr.
Modeling of the Simultaneous Evolution of Vacancy and Interstitial Dislocation Loops in hcp Metals Under Irradiation
Authors: Dubinko V , Turkin A , Abyzov A , Griffiths M
Published: May 2009

We present a model of the homogeneous nucleation and growth of vacancy and interstitial loops in irradiated hcp metals, which allows one to find the size distribution function, the dose dependence of the mean parameters of the dislocation system, and to describe effects due to temperature, material parameters, and initial microstructure. The model is based on a hierarchy of coupled ordinary differential equations. The first two equations are the rate equations for vacancy and interstitial concentrations. Other equations describe random walks of interstitial and vacancy clusters in a size space, i.e., the time dependence of loop densities. As an input, the model contains the capture efficiencies of point defects by loops, which depend self-consistently on the loop size and dislocation density. We have considered two possible scenarios depending on the point defect dilatation volume ratio: (i) dislocation bias for interstitial atoms and (ii) dislocation bias for vacancies. The model results are qualitatively consistent with experimental observations of a coexistence of interstitial and vacancy dislocation loops on the same habit planes in Zr and other hcp metals. The temperature dependence of the resulting loop size distributions depends strongly on the material properties and the initial microstructure.
An Investigation of the Heaving Mechanism Related to Chromite Ore Processing Residue
Authors: Moon DH , Dermatas D , Chrysochoou M , Shen G
Published: May 2009

Significant heaving has been observed over time at chromite ore processing residue (COPR) deposition sites in Maryland and New Jersey. Confined swell tests were employed in order to investigate the geochemical mechanisms that lead to the manifestation of heave in COPR. Ettringite, a known heave culprit in cement and soil-related literature, was identified in numerous samples across the sites and was therefore considered as the primary heaving mechanism in COPR. In addition, other possible mechanisms, such as brownmillerite hydration to hydrogarnets, carbonation reactions, calcium aluminum chromium oxide hydrate (CAC) formation, and change of hydration state were also investigated. The confined swell tests were conducted under wet/dry cycles. Sulfate, carbonate, and chromate solutions were introduced to the samples during wet cycles in order to validate the different heaving hypotheses associated with phase transformations. The test results showed that swell development occurred only in COPR upon 0.7 mole/l sulfate addition. Furthermore, x-ray diffraction analyses confirmed the formation of ettringite in the COPR sample following the addition of sulfate. Conversely, carbonation reactions led to no height change or even to consolidation, while the formation of hydrogarnets and CACs could not be established. It was, therefore, demonstrated that ettringite formation is a thermodynamically powerful reaction and also a viable expansion and failure mechanism in COPR.
Investigation of Barium Treatment of Chromite Ore Processing Residue (COPR) 031
Authors: Chrysochoou M , Dermatas D , Moon DH , Christodoulatos C , Wazne M , French C , Morris J , Kaouris M
Published: May 2009

Barium addition to chromite ore processing residue (COPR) was investigated in order to address (a) the pronounced heaving phenomena that are associated with mainly the presence of ettringite and (b) hexavalent chromium leaching. Sulfate was added to representative samples of grey-black (GB) and hard-brown (HB) COPR to simulate worst-case conditions of sulfate influx and ettringite formation. Both the X-ray powder diffraction (XRPD) and the modeling results showed that ettringite is a thermodynamically favored reaction in COPR. The subsequent addition of barium lead to the formation of both barite and barium chromate, observed as solid solution between the two phases. Modeling results confirmed that barium sulfate is the more stable species that will dissolve ettringite and that barium chromate will also dissolve COPR chromate phases when sulfate is depleted. The Toxicity Characteristic Leaching Procedure (TCLP) test on GB samples showed that the optimal stoichiometry to maintain Cr and Ba TCLP concentrations below the U.S. Environmental Protection Agency regulatory limit of 5 and 100 ppm, respectively, lies between 1:1 (Ba to sulfate plus chromate ratio) and 1.5:1. The respective optimal stoichiometry for the HB COPR was found to be higher, between 2:1 and 5:1. Considering that COPR is actually a Cr-contaminated cement form, a further area of research is the identification of barium-containing wastes (i.e., heavy-metal sludges, contaminated soils, etc.) that would be suitable for combination with COPR; in this way, an environmentally sustainable yet cost-effective treatment application can be realized.
Residue Analysis on RPVOT Test Samples for Single and Multiple Antioxidants Chemistry for Turbine Lubricants
Authors: Sitton A , Ameye J , Kauffman RE
Published: May 2009

Antioxidant chemistry is playing an important role in meeting the longer-life and higher temperature performance criteria of modern generation turbine lubricants. Oxidative life assessment is therefore an important parameter as part of today's turbine oil diagnostic services, where methods such as RPVOT, FTIR, and RULER are being applied. With this paper, we will discuss how RPVOT (per ASTM D 2272) testing of turbine lubricants with single antioxidant systems have much better reproducibility and repeatability than comparable RPVOT testing of oils with complex, synergistic mixtures of antioxidants. Both new and used turbine oils obtained from gas and steam turbines were used to assess the effects of antioxidant chemistry on the RPVOT results. In the first part of this research program, we present the analytical results for the residues remaining at the completion of the RPVOT tests of single component antioxidant oils. The RULER, varnish potential index (VPI), FTIR, AN, and viscosity analyses of the residues are very similar indicating that the residues contain no remaining antioxidants and have elevated levels of VPI, AN, viscosity, and FTIR oxidation, i.e., all of the RPVOT residues of the single antioxidant oils are highly oxidized when the test is ended based on oxygen uptake. In the second part, we present the analytical results for the RPVOT residues of complex mixture antioxidant oils. In contrast to the single antioxidant oils, the analytical tests of the complex antioxidant RPVOT residues indicate that the concentration of antioxidant and the level of oxidation varies with antioxidant formulation when the test is ended based on oxygen uptake. The results presented in this paper indicate that the effects of antioxidant chemistry on the residue content of RPVOT tests help explain the poor reproducibility of the RPVOT tests for turbine oils containing different types of antioxidant systems. Consequently, RULER analyses to characterize the antioxidant systems of the turbine oils before and after RPVOT testing would be very valuable in interpreting the RPVOT results and in improving the reproducibility of the RPVOT technique for making oxidative life assessments of modern generation turbine lubricants. VPI assessments of the turbine oils would further improve the oil diagnostic services of turbine lubricants by providing insight into the capability of the lubricants to solubilize the oxidation products of the antioxidants and the highly-refined base-oil.
Oxygen Fires in Aluminum Alloy Cylinders
Authors: Barthélémy H
Published: May 2009

One of the most frequently asked questions in the oxygen compatibility world is whether aluminum is compatible with oxygen. The answer is yes for high pressure aluminum alloy (AA) cylinders, and this is proven by the fact that several million AA cylinders are safely used around the world every day. However, some accidents have occurred with AA cylinders in oxygen service. In this paper, two main accident types are described and illustrated. The first accident occurred when devalving a cylinder which was under full pressure, resulting in a violent explosion and burning of a large part of the cylinder shoulder. The second accident occurred when a cylinder was dropped from a height of about 400 mm; again the cylinder exploded and again a large part of the cylinder shoulder burned. Tests were conducted in an attempt to understand the ignition mechanisms. In this paper, the ignition mechanisms are explained and recommendations are provided to prevent reoccurrences.
Prediction of Failure in Existing Heart Valve Designs
Authors: Koppenhoefer KC , Crompton JS , Dydo JR
Published: May 2009

Artificial heart valves must be designed to survive greater than 109 cycles over 40 years of operation. Thus, fatigue represents one of the primary driving forces for safe operation of these devices. The inability to maintain the long term performance of critical devices in the future may lead to catastrophic failure and patient loss of life. The Bjork-Shiley convexo-concave (BSCC) heart valve provides an excellent case study in heart valve design. Approximately 86 000 valves were implanted from 1979 to 1987 and approximately 1 % of the valves experienced failure due to fatigue. Failures of this type are likely to yield a 70 % mortality rate in patients. To understand the conditions that produced failure, a detailed engineering assessment was conducted to determine valve designs, manufacturing processes, and physiologically related loading conditions that gave rise to an increased risk of failure. The material used in constructing the valve, Haynes 25, possesses good long crack threshold fatigue properties (ΔKth=4.5MPam). However, continued operation of the valves produced cracking under certain physiological circumstances. These assessments indicate that a small subset of valves may operate under conditions that are close to the boundary between continued safe operation and catastrophic failure. These findings should be considered when using materials with inherently lower threshold fatigue properties. Crack growth data show that Nitinol has a threshold stress intensity factor MPa ≈2MPam, or less than half that of Haynes 25. Thus, current heart valve designs that use Nitinol should incorporate lessons learned from analyses of the BSCC heart valve to assess the likelihood of premature valve failure due to repeated loading.
Gravimetric Analysis of the Nonvolatile Residue from an Evaporated Droplet, Using the Quartz Crystal Microbalance/Heat Conduction Calorimeter
Authors: Smith AL
Published: May 2009

A quartz crystal microbalance/heat conduction calorimeter (QCM/HCC) has been used to determine the nonvolatile residue at the parts-per-million level in 10 µL droplets of methanol and a 45 µL droplet of water. The QCM was used to measure the mass of the nonvolatile residue, and the calorimeter was used to determine the mass of the solvent by the heat required to evaporate the droplet.
A Screening Bioassay Using Daphnia pulex for Refinery Wastes Discharged into Freshwater
Authors: Buikema AL , Lee DR , Cairns J
Published: May 2009

A simple method using unsophisticated equipment is suggested for on-site toxicity testing of refinery effluents. This method will provide an inexpensive means of identifying problem materials and establishing priorities for coping with these materials. An arbitrary reference mixture, containing six common constituents of refinery wastewaters, was used for static toxicity tests on 15 species of freshwater invertebrates and 3 species of fish. Daphnia pulex was selected for further testing because it was the most sensitive of the animals tested, relatively inexpensive and easy to maintain, and a potential fish-food organism. If the reference mixture were representative of a refinery effluent, the Daphnia bioassay would be sufficiently sensitive to give reliable results within 48 h, whereas a fish bioassay would show no toxicity even after 96 h.

To assess the suitability of the Daphnia bioassay, tests were conducted by personnel at six petroleum refineries. Duplicate tests were in agreement. Results of tests using actual refinery effluents ranged from no toxicity after 96 h to a mean lethal concentration of 1.2% effluent after 48 h. The data presented show that the method was reproducible and that refinery personnel were able to perform the bioassay. Potential problems and advantages of the method are discussed.
Salt Water and Hydrogen Sulfide Corrosion Fatigue of Work-Hardened, Threaded Elements
Authors: Bellow DG , Faulkner MG
Published: May 2009

This work describes the results of a laboratory testing program undertaken to evaluate the merits of work-hardened, threaded machine elements when subjected to axial fatigue in the presence of a corrosive environment. The experimental apparatus is described, including details of the corrosive mediums. The most damaging corrosive medium consisted of a salt water solution through which hydrogen sulfide gas was bubbled. Lower corrosion fatigue damage was noted for aerated salt water and the least occurred for a deaerated salt water solution. The corrosion fatigue results are compared with results obtained in air for simple cut threads and fully cold-worked or rolled threads formed on AISI 8635 steel. The results show that at a life of 105 cycles the fully cold-worked threaded element had an endurance stress of 74 ksi (510 MPa) compared with 44 ksi (303 MPa) for the simple cut threaded element. Under the combined action of corrosion fatigue in the presence of a hydrogen sulfide saline solution these values were reduced to 46 ksi (317 MPa) and less than 20 ksi (138 MPa), respectively, which indicated that the fully cold-worked, threaded element was superior to all thread forms evaluated under a variety of environmental conditions.
Fracture Criteria for Brittle Materials
Authors: Ehrenburg DO
Published: May 2009

The behavior of brittle materials under biaxial and triaxial loading is predictable on the basis of stress envelopes derived from the properties of idealized materials. In the case of nonmetallic brittle materials, the idealized patterns must be somewhat modified to allow for the low tensile strength of these materials. Two basic criteria are recognized: one related to the angle of internal friction, the other a limiting-stress criterion (in tension). The paper culminates in the construction of three-dimensional stress envelopes by means of contours.
Characterization of Polymeric Materials by Dynamic Mechanical Properties
Authors: Seefried CG , Koleske JV
Published: May 2009

The determination and analysis of dynamic mechanical properties provide valuable information to characterize polymeric materials. Such testing of polymers with a torsional pendulum is a relatively simple procedure which requires a small amount of sample and is especially sensitive to changes in molecular structure. Thus, the dynamic mechanical properties of polymeric materials can be related directly to the composition, chemical structure, and morphology of the polymer chains. Data are presented which demonstrate the utility of dynamic mechanical properties in the evaluation of polymeric systems based on the presence of crystalline material, the addition of chemical crosslinks, the incorporation of a plasticizer, and copolymers or blends which exhibit various degrees of component compatibilities. The analytical characteristics of particular interest include the glass transition temperature(s) of the material, the occurrence of any secondary relaxations, and the relative change in modulus values and loss properties, all as functions of temperature and time.
The Feasibility of Ranking Material Fracture Toughness by Ultrasonic Attenuation Measurements
Authors: Vary A
Published: May 2009

A preliminary study was conducted to assess the feasibility of ultrasonically ranking material fracture toughness. Specimens of two grades of maraging steel for which fracture toughness values were measured were subjected to ultrasonic probing. The slope of the attenuation coefficient versus frequency curve was empirically correlated with the plane strain fracture toughness value for each grade of steel.
Environmental Stress Cracking of Thermoplastics: A New Approach to Testing
Authors: Henry LF
Published: May 2009

A flexural relaxometer is described for use in characterizing the environmental stress cracking tendencies of glassy plastics. Testing procedures are discussed and data indicating critical strain values, rates of cracking, and rates of dissolution are presented.
Comparisons of Determinations of Wool Fiber Diameter by Two Airflow Methods
Authors: Kirby CK , Johnson CL , Larsen SA
Published: May 2009

Sixty scoured wool core samples were measured for fiber diameter by three different methods. Mean diameters of the samples were determined by the projection microscope method and used to place each sample in one of six classes. The interval of each class was 2.5 μm; diameters ranged from 17.5 to 32.5 μm. The specimens, first uncarded and then carded, were next measured on the Port-Ar® and the Wool Industries Research Association Fibre Fineness Meter®. Carding of the samples prior to measurement was concluded to be unnecessary as no significant differences were found (P < 0.05) between results. This was true for both airflow methods.

Regression and correlation coefficients of one airflow method versus the other were significant (P < 0.01). Based on the regression analysis, it was concluded that a conversion from one airflow method to the other may be acceptable. Confidence limits at the 99% probability level for such conversions are not greater than ± 1 μm.
Block Concrete Is a Structural Material
Authors: Holm TA
Published: May 2009

New methods for determining the tensile strength of block concrete are described. Results of tests on the tensile strength and elastic stiffness are reported and found to parallel the results of test data developed on structural cast-in-place concrete. Maximum strain relationships (extensibility) are compared for various concrete densities. Production control of the physical properties of block concrete are described and recommendations for future research and change of ASTM requirements are listed.
Screening Test for Torsional Creep Performance of Plastics
Authors: Gonzalez H
Published: May 2009

The objective of this project was to determine the usefulness and limitations of a modified indentation hardness test in determining the creep resistance of plastics. Tests were run on 13 different materials and correlations were made between the modified hardness test and torsional creep tests at a 1000-psi (6895-kPa) stress level up to 500 h. The modified hardness test may be used as a screening test for creep performance as it allows determination of expected creep performance at a very early stage of material evaluation, where there are usually limited amounts of material available. Equations were developed to allow the prediction of creep performance. The correlations developed are not applicable to anisotropic materials.
Fatigue Damage Alleviation by Intermittent Electroplating
Authors: McKinnon EA
Published: May 2009

The fatigue life of copper can be extended by intermittently electroplating layers of nickel onto the copper. By electroplating every 25% of the anticipated life, the fatigue life of copper cyclically stressed at ± 14 500 psi (± 99 974 kPa) can be extended indefinitely.
Origin of Burst-Type Acoustic Emission in Unflawed 7075-T6 Aluminum
Authors: Bianchetti R , Hamstad MA , Mukherjee AK
Published: May 2009

Tensile tests were used to study the acoustic emission from several 7075-T6 aluminum plates. Specimens from one plate produced a large burst-type emission in addition to the continuous emission. Metallographic and fracture surface studies indicated that the burst-type emission resulted from the brittle fracture of large (20 to 60 μm) primary inclusions in the microstructure.
A Damage Function and Associated Failure Equations for Predicting Hold Time and Frequency Effects in Elevated Temperature, Low Cycle Fatigue
Authors: Ostergren WJ
Published: May 2009

A new approach is developed for predicting strain-controlled, low cycle fatigue life at elevated temperature using a proposed energy measure of fatigue damage. This measure of damage, defined as the net tensile hysteretic energy of the fatigue cycle, can be approximated by the damage function σTΔεp, where σT is the maximum stress in the cycle and Δεp is the inelastic strain range. The damage function is applied to predicting effects of hold time and frequency, when time-dependent damage occurs, through failure relations incorporating a variation of Coffin's frequency modified approach. Failure equations are developed for two postulated categories of time-dependent damage.
Red Mud from Alumina Plants as a Possible Source of Synthetic Aggregate
Authors: Blank HR
Published: May 2009

Red mud, from an alumina plant at Point Comfort, Texas, molded into balls and heated in a muffle furnace to 2300 to 2400°F (1260 to 1316°C), partially crystallizes and forms a strong, heavy, synthetic aggregate. Attempts to produce a lightweight aggregate by adding small amounts of gas-forming materials to the red mud before heating were unsuccessful. The additives used and the products formed are described. Apparently the red mud does not soften until heated to nearly 2400°F. Gases given off at lower temperatures either blow the aggregates apart or escape through cracks without expanding the mass.
Strength and Toughness of a Metastable Beta-Titanium Alloy as Influenced by Strain Rate Variations
Authors: Chait R
Published: May 2009

Strain rate effects for the high strength, metastable beta-titanium alloy Ti-8Mo-8V-2Fe-3Al are assessed in terms of tensile and fracture toughness behavior. It is shown that as the strain rate increases the yield strength, ultimate tensile strength, and ductility also increase. As a result of the decrease in the amount of intergranular fracture as the strain rate is increased, the dynamic fracture toughness values KId are greater than those obtained under static conditions as given by KQ.
Variations in Magnetic Properties of Iron-Cobalt-Vanadium Alloys
Authors: Pinnel MR
Published: May 2009

Considerable variability in the magnetic properties of an iron-cobalt-vanadium alloy wire processed by commercial vendors has been observed. To ascertain the cause of and cure for this variability, a two-part study utilizing microstructural characterization and statistical evaluation of magnetic data was implemented. Results indicate that wire microstructure, and hence magnetic properties, vary both from wire coil to wire coil within a given melt and along the length of a coil of wire. This variation can be attributed to fluctuations in furnace temperature during the 900 to 950°C strand anneal of the wire. A correlation exists for magnetic properties between the strand-annealed and final aged at 600°C conditions such that evaluation of coercivity and remanence in strand-annealed wire may be feasible for detecting incoming, improperly heat-treated coils at inspection.