bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of the levonorgestrel-releasing intrauterine system on the resistance to activated protein C (APC)
Authors: Tchaikovski Svetlana , Rosendaal Frits , Rosing Jan , Helmerhorst Frans , van Vliet Huib
Published: March 2009

Exogenously administered estrogens and progestogens as during combined oral contraceptive use increase the risk of venous thrombosis. The thrombin generation-based APC resistance assay is a global coagulation test that enables quantification of the net prothrombotic effect of combined oral contraceptives and that predicts the risk of thrombosis. The thrombotic risk of the levonorgestrel-releasing intrauterine system is unknown. It was the objective of this study to evaluate the thrombotic risk by comparing the APC resistance before and after insertion of a levonorgestrel-releasing or a copper-containing intrauterine device. We measured normalized APC-sensitivity ratios (nAPCsr) before and three months after insertion of the levonorgestrelintrauterine system in 56 women and the copper-intrauterine device in 18 women. In women without hormonal contraceptive use or a pregnancy in the three months before collection of the baseline samples, nAPCsr were lower three months after insertion of the levonorgestrel-intrauterine system than at baseline (difference –0.29; 95% CI –0.04 to –0.53) and hardly changed after insertion of the copper-intrauterine device (difference -0.11; 95% CI –1.03 to 0.82). In women who switched from a combined oral contraceptive to the levonorgestrel-system the difference was more pronounced (-1.48; 95% CI –0.85 to –2.11). In this study we observed that the levonorgestrel-intrauterine system decreases the resistance to APC which indicates that the levonorgestrel-intrauterine system does not have a prothrombotic effect.
Role of H2O2-activated TRPM2 calcium channel in oxidant-induced endothelial injury
Authors: Hecquet Claudie , Malik Asrar
Published: March 2009

The transient receptor potential (melastatin) 2 (TRPM2), is an oxidant-activated non-selective cation channel that is widely expressed in mammalian tissues including the vascular endothelium. Oxidative stress, through the generation of oxygen meta-bolites including H2O2, stimulates intracellular ADP-ribose formation which, in turn, opens TRPM2 channels. These channels act as an endogenous redox sensor for mediating oxidative stress/ROS-induced Ca2+ entry and the subsequent specific Ca2+-dependent cellular reactions such as endothelial hyper-permeability and apoptosis. This review summarizes recent findings on the mechanism by which oxidants induce TRPM2 activation, the role of these channels in the signalling vascular endothelial dysfunctions, and the modulation of oxidant-induced TRPM2 activation by PKCα and phospho-tyrosine phosphates L1.
Signalling pathways in ischaemic postconditioning
Authors: Hausenloy Derek
Published: March 2009

Coronary heart disease (CHD) is the leading cause of death globally. Following an acute coronary artery occlusion, timely myocardial reperfusion using either primary percutaneous coronary intervention (PCI) or thrombolytic therapy remains the most effective treatment strategy for reducing myocardial infarct size, preventing left ventricular remodelling, preserving left ventricular systolic function and improving clinical outcomes. However, the full benefits of myocardial reperfusion are not realised, given that the actual process of reperfusing ischaemic myocardium can independently induce cell death – a phenomenon termed lethal reperfusion injury. Ischaemic postconditioning represents an innovative treatment strategy for limiting lethal myocardial reperfusion injury and further reducing myocardial infarct size for those patients undergoing primary PCI. It is achieved by interrupting the normal myocardial reperfusion process, with several intermittent episodes of coronary myocardial ischaemia induced by low-pressure inflations of the angioplasty balloon in the infarct-related coronary artery. Experimental studies demonstrate that this stuttered form of myocardial reperfusion improves myocardial perfusion, maintains endothelial function, attenuates apoptotic cell death, reduces myocardial infarct size, preserves left ventricular systolic function and reduces mortality. The mechanisms underlying the cardioprotective effect of ischaemic postconditioning are the subject of intense investigation. In this article we review the signalling pathways which have been implicated as potential mediators of ischaemic postconditioning, the identification of which have provided novel pharmacological targets of cardioprotection capable of recapitulating the protective benefits of ischaemic postconditioning.
Myocardial protection against reperfusion injury: The cGMP pathway
Authors: Agulló Luis , Sartorio Carmem Lluisa , Ruiz-Meana Marisol , Garcia-Dorado David
Published: March 2009

Reperfusion injury may cause myocardial cell death and limit the benefit achieved by restoration of coronary artery patency in patients with acute myocardial infarction. The mechanism includes altered Ca2+ handling with cytosolic and mitochondrial Ca2+ overload, Ca2+- and ATP-dependent hypercontraction, cytoskeletal fragility, mitochondrial permeability transition and gap junction-mediated propagation of cell death, as well as alterations in non-cardiomyocyte cells, in particular platelets and endothelial cells. cGMP modulates favorably all these mechanism, mainly through PKG-mediated actions, but cGMP synthesis is altered in reperfused cardiomyocytes and endothelial cells by mechanisms that are only partially understood. Stimulation of cGMP synthesis during initial reperfusion by means of natriuretic peptides has been found protective in different animal models and in patients. Moreover, increasing evidence indicates that cGMP is an important step in signal transduction of endogenous cardioprotection. Thus, the cGMP pathway appears as a key element in the pathophysiology of myocardial ischaemiareperfusion and as a promising therapeutic target in patients with acute myocardial infarction.
Acquired factor V inhibitor
Authors: Kuperan Ponnudurai , Ng Chin Hin , Ng Heng Joo , Ang Ai Leen
Published: March 2009

Acquired factor V(FV) inhibitors as a rare bleeding disorder, poses a formidable challenge to treating physicians with limited evidence to guide its management. We systematically reviewed our experience in Singapore and the published literature to determine possible answers to clinical questions formulated on the manifestation and best management of non-bovine thrombin and non-congenital acquired FV inhibitors. The incidence in Singapore was 0.09 cases per million person years (3 cases over 10 years). Seventy-three other cases meeting pre-defined search criteria were found in the published literature. Bleeding occurred in 68.4% of these patients, with mucous membranes being the most common site. Intracranial and retroperitoneal bleeds carried the highest mortality. The mortality rate from bleeding was 12%. There was a tendency for FV levels and PT/aPTT prolongation to predict bleeding but not the inhibitor level. No consistently effective haemostatic agent could be determined, but platelet transfusion should probably be the first line therapy. Among bleeding patients, inhibitors tended to disappear faster with inhibitor elimination therapy (IET) compared to without IET (60 vs. 150 days, p=0.299). IET made no significant difference among non-bleeding patients (p=0.511) and is thus recommended for bleeding patients or those with high bleeding risk. Steroids as single agent IET was effective in the majority of patients. Logical management approaches may be drawn but are limited by small sample size, heterogeneity of reports, and potential publication bias. The inception of a comprehensive registry will provide more reliable data that may verify our findings.
Comments on “Does Air Pollution Really Suppress Precipitation in Israel?”
Authors: Givati Amir , Rosenfeld Daniel
Published: March 2009

Alpert et al. in a recent paper challenged the quantification of the suppression of orographic precipitation that was shown in two recent papers by Givati and Rosenfeld to occur in Israel. Their main claim was that the results were determined by the selection of the rain gauges. In this comment, it is demonstrated that when an objective selection of the rain gauges is applied to all of the rain gauges that were used by Alpert et al. and Givati and Rosenfeld, the outcome replicates the results of Givati and Rosenfeld and provides additional insights. At the final account, this comment further enhances the confidence that orographic precipitation has been suppressed over Israel. The direct evidence to the cause is still lacking.
Hating Israel in the Field
Authors: Hage Ghassan
Published: March 2009

This article chronicles the beginning of my fieldwork among Lebanese Shi'a in South Lebanon and in the diaspora. The fieldwork coincided with Israel's 2006 bombardment of Lebanon that destroyed its only just rebuilt infrastructure, killed more than 1000 civilians and left behind in agricultural areas and villages thousands of unexploded cluster bombs. The village where I was preparing to do my fieldwork was destroyed and my prospective key informant was killed. The scene among the South Lebanese Shi'a immigrants in Sydney became one of generalized mourning. There was an overwhelming feeling of anger and hatred towards Israel. In this article, I scrutinize the ambivalence emanating from sharing `political emotions' with my informants. I argue that such a situation generates another set of emotions that are specific to ethnographic practice that I call, borrowing from Spinoza, `ethnographic vacillation'.
Displacing the subject
Authors: Hayden Bridget
Published: March 2009

Dialogical epistemologies of the self have been influential in rethinking the politics of ethnography. Although critiquing the centered Cartesian self as the locus of knowledge, these approaches focus attention on the researcher and assume the primacy of the self-knowing subject. This article draws on Peirce's argument that `man' is a sign to supplement critical theories of knowledge. Although Peirce focused on the semiosis of consciousness, we can apply his interpretive framework to think about other interpretants of the researching sign, the discourses that shape the meanings of the self as sign, and the hazards of the ethnographic encounter.
Shoulder Pain in the Overhead Throwing Athlete
Authors: Seroyer Shane T. , Nho Shane J. , Bach Bernard R. , Bush-Joseph Charles A. , Nicholson Gregory P. , Romeo Anthony A.
Published: March 2009

Treatment of the overhead throwing athlete is among the more challenging aspects of orthopaedic sports medicine. Awareness and understanding of the throwing motion and the supraphysiologic forces to which the structures of the shoulder are subjected are essential to diagnosis and treatment. Pain and dysfunction in the throwing shoulder may be attributed to numerous etiologies, including scapular dysfunction, intrinsic glenohumeral pathology (capsulolabral structures), extrinsic musculature (rotator cuff), or neurovascular structures. Attention to throwing mechanics and appropriate stretching, strength, and conditioning programs may reduce the risk of injury in this highly demanding activity. Early discovery of symptoms, followed by conservative management with rest and rehabilitation with special attention to retraining mechanics may mitigate the need for surgical intervention. Prevention of injury is always more beneficial to the long-term health of the thrower than is surgical repair. An anatomic approach is used in this report, focusing on common etiologies of pain in the overhead thrower and emphasizing the clinical presentation and treatment.
Novel Design of Dual Functional Hydrogen Separation Membranes
Authors: Song Sun-Ju , Lee Tae H , Dorris Steve E , Balachandran U (Balu)
Published: March 2009

The novel design of cermet membranes is reported here, which are capable of simultaneously transporting two gas species through membrane metal with high hydrogen permeability in a thermodynamically stable oxygen-ion-conducting ceramic matrix. This novel, dual-function cermet membrane should allow the maximum hydrogen production by combining the ability of hydrogen production from water with the function of hydrogen separation on membranes. An hydrogen production rate of ca. 2.7 cm3(STP)/min·cm2 for 0.21-mm-thick membrane at 900 °C was obtained, using 50 vol % water vapor on one side of the membrane and 80%/20% hydrogen/helium on the other side.
Sources and Sinks of Carbon Dioxide
Authors: Quirk Tom
Published: March 2009

The conventional representation of the impact on the atmosphere of the use of fossil fuels is to state that the annual increases in concentration of CO2 come from fossil fuels and the balance of some 50% of fossil fuel CO2 is absorbed in the oceans or on land by physical and chemical processes. An examination of the data from:

i) measurements of the fractionation of CO2 by way of Carbon-12 and Carbon-13 isotopes,

ii) the seasonal variations of the concentration of CO2 in the Northern Hemisphere

and

iii) the time delay between Northern and Southern Hemisphere variations in CO2,

raises questions about the conventional explanation of the source of increased atmospheric CO2. The results suggest that El Nino and the Southern Oscillation events produce major changes in the carbon isotope ratio in the atmosphere. This does not favour the continuous increase of CO2 from the use of fossil fuels as the source of isotope ratio changes. The constancy of seasonal variations in CO2 and the lack of time delays between the hemispheres suggest that fossil fuel derived CO2 is almost totally absorbed locally in the year it is emitted. This implies that natural variability of the climate is the prime cause of increasing CO2, not the emissions of CO2 from the use of fossil fuels.
Can we Predict the Next Indian Mega-Famine?
Authors: Wilson Ian R. G.
Published: March 2009

Catastrophic multi-year failure of the Indian monsoon has caused at least eight mega-famines in India over the last 1100 years. Historical data shows that seven out of the eight mega-famines have either started within ± one year of the year of greatest asymmetry in the Sun's motion about the Solar System's centre-of-mass, or 11 years ± one year after this event. The Sun is currently experiencing a maximum in the asymmetry of its motion about the centre-of-mass. Evidence is presented to show that there is almost a 1-in-4 the chance that there will be another Indian mega-famine in 2018–20. While the chance of such a catastrophic event occurring is small, it is large enough that the governments on the Indian subcontinent should take precautionary measures to confront this potentially devastating threat.
Cooling of the Global Ocean since 2003
Authors: Loehle Craig
Published: March 2009

Ocean heat content data from 2003 to 2008 (4.5 years) were evaluated for trend. A trend plus periodic (annual cycle) model fit with R2 = 0.85. The linear component of the model showed a trend of −0.35 (±0.2) x 1022 Joules per year. The result is consistent with other data showing a lack of warming over the past few years.
Climate Change: Dangers of a Singular Approach and Consideration of a Sensible Strategy
Authors: Ball Timothy F.
Published: March 2009

The Intergovernmental Panel on Climate Change (IPCC) has convinced many, including most governments, that the only future is global warming. IPCC's structure and directions required it only examine human causes of climate change. It also created a view that warming was only disastrous. Actually, there are more benefits to warming than cooling. Evidence indicates cooling is already occurring, because of changes in solar activity. Cooling is much more problematic. A logical strategy regardless of the trend is to prepare for cooling. Adaptation to warming is easier than to cooling.
The Earth in an Electric Solar System
Authors: Hissink Louis A.G.
Published: March 2009

Since Isaac Newton's time till the present, science has described the universe in terms of his laws of gravitation without explanation but since the development of the modern industrial age electrical engineers have also noted unexpected electromagnetic behaviour in the various engineered systems humanity uses whether on land, in the oceans and in space. The electromagnetic solar connection is best explained by theories of the electric plasma universe in which the Earth is thought to be electro-dynamically connected to the electric plasma of space. Laboratory plasma experiments and particle-in-cell computer simulations using the equations of Maxwell and Lorentz have accurately described galaxy morphology and motions, and from the scalability of plasma phenomena, it is possible to explain other similar rotary phenomena such as Earth based hurricanes. This paper is a brief summary of the more salient aspects of the Earth's electrical plasma environment.
Limits on CO2 Climate Forcing from Recent Temperature Data of Earth
Authors: Douglass David H. , Christy John R.
Published: March 2009

The global atmospheric temperature anomalies of Earth reached a maximum in 1998 which has not been exceeded during the subsequent 10 years. The global anomalies are calculated from the average of climate effects occurring in the tropical and the extratropical latitude bands. El Niño/La Niña effects in the tropical band are shown to explain the 1998 maximum while variations in the background of the global anomalies largely come from climate effects in the northern extratropics. These effects do not have the signature associated with CO2 climate forcing. However, the data show a small underlying positive trend that is consistent with CO2 climate forcing with no-feedback.
Earth's Radiative Equilibrium in the Solar Irradiance
Authors: Hertzberg Martin
Published: March 2009

The average equilibrium temperature for all the Earth's entities involved in its radiative balance with the Sun and Space, is given by:

T (e) [K] = 278.9 [(1 - α) / ɛ]

The controlling factor is the ratio of the absorptivity, a = (1 - α), to the emissivity, ɛ. The quantity α is the Earth's albedo. It is shown that relatively modest changes of only a few percent in α, brought about by variations in cloudiness, are sufficient to account for the observed 20th Century variations in Earth's measured temperature, provided that such variations in cloudiness can cause an imbalance in the ratio (1 - α) / ɛ. The analysis suggests that in the long run, the absorptivity to emissivity ratio is near unity, as required by Kirchhoff's radiation law, which ensures a moderate average temperature of about 5.7 C for the Earth's surface entities. That calculated temperature is in fair agreement with the observed average temperature of those entities, whose mass average is dominated by the mass of the oceans. Except for the influence of clouds on the albedo, no assumptions are needed regarding the detailed composition of the atmosphere in order to explain the observed small fluctuations in the 20th Century temperatures or the larger, longer-term variations of Glacial Coolings and Interglacial Warmings.
Evidence That Stainable Bone Marrow Iron Following Parenteral Iron Therapy Does Not Correlate With Serum Iron Studies and May Not Represent Readily Available Storage Iron
Authors: Thomason Ronald W. , Almiski Muhamad S.
Published: March 2009

We recently reported that parenteral iron therapy is associated with a characteristic pattern of iron staining on bone marrow aspirate smears. We now present clinical information from 6 patients who received parenteral iron and, at one or more points in follow-up, were found to have low or borderline low serum ferritin levels and/or serum iron levels, even though marrow aspirate smears revealed abundant stainable iron in the pattern characteristic of prior parenteral iron therapy. We conclude that stainable iron seen in this pattern does not correlate with serum iron studies and may not represent functionally available storage iron. This pattern of iron staining should not be used as evidence to withhold further iron therapy in patients who otherwise continue to have features of iron deficiency anemia.
Two-dimensional NMR studies of acrylate copolymers
Authors: Brar A. S. , Goyal Ashok Kumar , Hooda Sunita
Published: March 2009

High-resolution NMR spectroscopy is the most versatile, reliable, and generally acceptable technique for the determination of the microstructure of polymers. 2D NMR techniques, along with 1D NMR, have more potential to study absolute configurational assignments and sequence distribution of copolymers. Physical and chemical properties of polymers are influenced fundamentally by their microstructure. We discuss the detailed microstructure analysis of a large number of homopolymers, copolymers, and terpolymers. 2D NMR study of poly(methyl methacrylate) (PMMA), poly(methyl acrylate) (PMA), and poly(methacrylonitrile) (PMAN) is discussed in this article. In addition to homopolymers, 2D heteronuclear single-quantum coherence (HSQC), total correlation spectroscopy (TOCSY), and heteronuclear multiple-bond correlation (HMBC) study of different copolymers such as poly(methyl methacrylate-co-methyl acrylate), poly(styrene-co-methyl methacrylate), and poly(methyl methacrylate-co-methacrylonitrile) have also been reported here. This in turn helps in microstructural analysis of terpolymers such as poly(methacrylonitrile-co-styrene-co-methyl methacrylate), poly(acrylonitrile-co-methyl methacrylate-co-methyl acrylate), and poly(ethylene-co-vinyl acetate-co-carbon monoxide).
Gelation mechanism of ultra-high-molecular-weight polyethylene (UHMWPE) chains in dispersion solutions containing multiwall carbon nanotubes (MWNTs) analyzed in terms of liquid-liquid phase separation
Authors: Matsuo Masaru , Yamanaka Atsuko , Nakano Yumiko
Published: March 2009

Gelation mechanisms of ultra-high-molecular-weight polyethylene (UHMWPE) in dispersion solutions containing multiwall carbon nanotubes (MWNTs) were investigated in terms of liquid-liquid phase separation mechanisms. When an incident beam of He-Ne gas laser was directed to the dispersion solution quenched to a desired temperature, the logarithm of scattered intensity increased linearly with elapsing time and tended to deviate from this linear relationship. The two different increasing behaviors of the scattered intensity were termed as initial and latter stages, respectively, of the phase separation. The linear increase in logarithmic light-scattered intensity was analyzed within the framework of the linear theory of spinodal decomposition in terms of the viewpoint that the quenched solution becomes thermodynamically unstable and tends to incur phase separation to resolve the unstable state. The growth rate of the concentration fluctuation of neat UHMWPE solution (without MWNTs) calculated from the slope of linear increase was faster than that of the dispersion solution. In spite of the rapid growth rate, however, the gelation time of the dispersion solution was much shorter than that of the neat UHMWPE solution and the gelation and quasi-spinodal temperatures were slightly higher. These phenomena were in contradiction with the result of the concentration fluctuation. This contradiction was thought to be due to the fact that diffused UHMWPE chains in the dispersion solution were gelled easily on the MWNT surface rather than the gelation by self-coagulation.
Reliability and prediction of long-term performance of polymer-based materials
Authors: Brostow Witold
Published: March 2009

The prediction of long-term performance from short-term tests is the bottom line of polymer science and engineering for users of polymer-based materials (PBMs) - which means for scientists, engineers, and laymen, or, literally, for everybody. Methods of prediction of mechanical properties (creep, stress relaxation, dynamic mechanical behavior, tension, etc.) based on the chain relaxation capability (CRC), the stress-time and temperature-time correspondence principles are presented. The methods can be applied even to small amounts of experimental data (2 or 3 isotherms or 2 or 3 stress levels) and can produce much better results than the still used 1955 Williams-Landel-Ferry (WLF) equation. Successful applications of the CRC approach include multiphase systems, including polymer liquid crystal (PLC) copolymers. An extension to the tribological properties of PBMs (in particular, scratch healing) is outlined. A quantitative definition of materials brittleness was formulated in 2006; it is connected to results in both the mechanics and tribology of PBMs.
Punctuating a Neck: Adoption, Chroming and Crisis in the Life of a Family
Authors: Grimwade Jo
Published: March 2009

An extraordinary case is presented. The father had been admitted to an emergency ward following stabbing by his first son. The son had become uncontrollable and used many substances, constantly and reduced family life to a battleground with his mother. The two older boys were adopted, the third was miraculously conceived. In about ten sessions, the family's story was told in dramatic ways. Over twelve years later, the boys have become fathers and the grandparents are doting.
Relationship Between Water Solubility, Soil Sorption, Octanol-Water Partitioning, and Concentration of Chemicals in Biota
Authors: Kenaga EE , Goring CAI
Published: March 2009

There is a need for a method of preliminary estimation of bioconcentration factors in fish and soil sorption coefficients for chemicals. A data base was assembled for 170 compounds having average values for these two parameters and also average values for water solubility and n-octanol-water partition coefficients. Binary regression equations between the logarithms of these values gave correlation coefficients that were all significant below the 1 percent level. Using these equations, measured average values for any of the four parameters could be used to estimate average values for the unmeasured parameters. The 95 percent confidence limits for the calculated values were about ±1 to 3 orders of magnitude of the measured values. The relatively large variation of the actual from the predicted values was due both to the variation in the type of methodology used to make the measurements and also to the intrinsic variation in values attributable to the nature of the chemicals, the characteristics of the soils and fish, and the environmental conditions employed in the studies. Much less variation between actual and predicted values has been achieved when more uniform methodology is adopted for measuring these parameters. Despite the variability, the data are useful for early assessment of the potential for bioconcentration and mobility in the environment. Knowledge of the two factors is needed for hazard assessment in the environment.

Bioconcentration factor values for Daphnia appear to be as valid for correlation purposes as those for fish.
Effects of Gas Turbine Engine Load Spectrum Variables on Crack Propagation
Authors: Macha DE , Grandt AF , Wicks BJ
Published: March 2009

This paper describes results of an elevated temperature fatigue crack growth study in IN-100, a nickel-base superalloy. The objective of this study was to determine if conventional fracture mechanics techniques can predict crack growth under conditions expected to occur in jet engine turbine disks. Results are reported for two types of experiments. The first group of tests examines isolated load events that may occur in a turbine disk load history. The influence of tensile overloads, compressive underloads, overload/underload sequences, and periods of sustained load on subsequent constant amplitude fatigue crack growth are discussed. The second group of specimens was subjected to a spectrum load history that combines many of the isolated load events. Cumulative damage crack growth predictions are performed by several procedures and shown to agree quite well with the experimental results. The influence of specimen thickness is considered for both the isolated event and the spectrum loading experiments.
Microstructure, Slip Distribution, and Strain Hardening in Aluminum Alloys
Authors: Sanders RE
Published: March 2009

A microstructural approach has been used to explain the deformation characteristics which influence the formability of aluminum alloy sheet materials. Optical metallography and transmission electron microscopy were used to study the response of various aluminum alloys to uniaxial and biaxial deformation. The predominant strengthening mechanisms for a given alloy had the strongest effect on strain localization and biaxial strain hardening behavior. Dispersion-strengthened alloys displayed a wavy slip mode, and high levels of strain hardening and resistance to strain localization. Precipitation or solid-solution-strengthened alloys exhibited more localized deformation and lower capacities for biaxial strain hardening.
Application of Formability Assessment to Autobody Outer Panels
Authors: Furubayashi T , Kojima M
Published: March 2009

Sheet metal formability in the press forming of autobody outer panels corresponds to the forming limits governed by fracture and geometrical defects. The geometrical surface defects are affected especially by the geometry of the die face. This kind of formability in a wider sense has been investigated by using simulated experimental dies of different geometry in the die face.

The forming limit relating to fracture is closely related to the r- and n-values, while the forming limit of surface defects is governed by the yield point.
Formability of INCOLOY Alloy MA 956: An Oxide Dispersion Strengthened Sheet Alloy
Authors: Robinson ML , Astley I
Published: March 2009

The objective of this work was to measure the formability of INCOLOY alloy MA 956 sheet. This alloy, an iron, 19.5 weight percent chromium, 4.5 weight percent aluminum alloy strengthened by a fine dispersion of yttrium oxide particles, was designed to exhibit good strength and corrosion resistance at 1100°C, for uses such as combustor components in gas turbine engines. Sheet formability was measured utilizing conventional techniques. Tension tests in the longitudinal, transverse, and 45-deg directions produced strength and ductility data, work hardening exponents, and the coefficient of anisotropy (r-value). Results of Swift cup tests were used to determine deep drawing characteristics. Olsen cup test results were used to rate the stretchability of the sheet and effectiveness of different lubricants. Strain analysis of specimens, via the grid technique, yielded failure strain data and a forming limit diagram was produced. Attempts to interrelate these formability indexes, utilizing methods developed for conventional sheet materials, met with varying amounts of success. Although not highly formable compared to conventional alloys, MA 956 does exhibit a usable degree of formability, indicating a capability to be formed into simple shapes.
Upsetting Test for Determining Stress-Strain Curves in the Range of Very High Strains
Authors: Pöhlandt K , Roll K
Published: March 2009

In the upsetting test, stress-strain curves can be determined up to very high strains. However, two sources of error make the result increasingly inaccurate with growing strain: friction, and the error of measurement of the instantaneous specimen height.

Two methods are described by which these errors—or at least one of them—can be suppressed. The first method consists in the use of specimens according to Rastegaev. These specimens give excellent lubrication conditions and remain almost exactly cylindrical during testing, but the measurement of the instantaneous specimen height is even more inaccurate than for conventional specimens.

In the second method, both errors are suppressed by using a new kind of specimen, the diameter of which is larger at the ends than in the middle section. As a result, the work required for friction is suppressed, and in addition the error of height measurement propagates only weakly into the calculated values of strain and stress. This is demonstrated both by experiments and by calculations based on the finite-element method.
Computer-Aided Modeling of Selected Sheet Metal Forming Processes
Authors: Subramanian TL , Nagpal V , Altan T
Published: March 2009

Sheet metal forming processes, such as brake bending, rubber forming, and punch stretch forming, have significant use in manufacturing aircraft, automotive, and appliance parts. Computer-aided modeling and simulation of these processes provides information for production planning, for equipment and tooling selection, and for predicting potential failure during forming. Mathematical models and computer programs are developed to analyze and simulate these widely used sheet forming processes. The validity of these process models and the accuracy of the predicted results were evaluated by laboratory and production site tests.
Formability Testing for Precision and Accuracy
Authors: Niemeier BA
Published: March 2009

The author views the ability to shape press-formed parts with the logic and reason that are definitive of science. Materials which are in existence and those which are being developed for shape changeability are considered from intrinsic and extrinsic characteristics of force-deformation situations. Both mathematical modeling and statistics of precision and accuracy are introduced for direct measurements, such as depth to fracture. Elasticity and plasticity characteristics, which are both dimensionalized and nondimensionalized parametric relationships, are related to the fundamental physical variables of force and length.

Precision and accuracy are first presented in a simplistic format. Common and not-so-common parametric terms, such as stress, strain, strain hardening, and texture hardness, are used to indicate significance of precision. While numbers, charts, graphs, and equations are provided to handle abstract variables, full insight into the complete phenomena of numerical precision and accuracy remains with each investigator.

Levels of success and failure in correlating formability response are described from selected cooperative research. Included are encoded data from a large number of industrial and academic mechanical testing laboratories. Inter- and intralaboratory comparisons are related. There is the zone of uncertainty which may be deduced from a zone of confusion. Correlation or lack of the same is ascribed to an inadequately small zone of uncertainty. Statistical viewpoints of the author are offered through an in-depth level of references.
Finite Element Analysis of Biaxial Stress Test Specimen for Graphite/Epoxy and Glass Fabric/Epoxy Composites
Authors: Marloff RH
Published: March 2009

Finite element analyses of a diametrally loaded circular test specimen proposed for biaxial stress testing of composite materials are described. Two orthotropic material systems were investigated: unidirectional graphite/epoxy and glass/epoxy woven fabric. For the former, the stress distributions in the gage section were obtained for various loading angles. In general, the stresses did not agree with the uniform stress assumption based on force equilibrium except for the case corresponding to pure shear. Probable failure locations on the specimen boundary rather than in the gage section were identified for all loading angles by using a tensor polynomial failure criterion. Test results for the pure shear loading case confirmed the predicted failure location. Two geometry modifications were investigated as to their effect on this failure location. One of these, consisting of the removal of the small radius at the end of the gage section, warrants further investigation.

Examination of the E-glass/epoxy woven fabric material for the pure shear loading case showed a more uniform stress state in the gage section and the absence of a potential failure point on the boundary. Thus the test specimen shows promise for the determination of shear properties for such materials.
Stiffness Reduction as an Indicator of Damage in Graphite/Epoxy Laminates
Authors: Camponeschi ET , Stinchcomb WW
Published: March 2009

Changes in the stiffness of graphite epoxy laminates were experimentally investigated as indicators of fatigue damage. Five laminate orientations were considered: [0]4, [90]4, [±45]8, [0.90]8, [0.90,±45]8, and four inplane stiffness properties were monitored for each. The stiffness components were Exx, Eyy, Gxy, and , and vxy and were measured using a longitudinal tension test, a rail shear test, and a transverse bend test. Nondestructive testing techniques such as C-scan and edge replication were also performed to aid in the observation of damage development.

Results describe the response of each laminate orientation in tension-tension fatigue, including a record of changes in the stiffness properties at intervals during fatigue.

Longitudinal stiffness (Exx) and shear stiffness (Gxy) were shown to significantly decrease for the [0.90,±45]8 laminate following fatigue loading. The inplane stiffness properties for the other four laminates remain essentially unchanged following fatigue loading. Matrix cracking and delamination appear to contribute to the stiffness reductions that occur in the [0.90,±45]8 laminate, although the damage state and attendant stifness changes are not simple functions of the response of the constituent laminae.
Influence of Frequency and Environmental Conditions on Dynamic Behavior of Graphite/Epoxy Composites
Authors: Putter S , Buchanan DL , Rehfield LW
Published: March 2009

The purpose of this research is to experimentally determine the combined influence of frequency and environmental conditions on dynamic behavior of graphite/epoxy composites. The new additions to the data base on dynamic behavior facilitate confident use of these composites in applications.

This objective has been accomplished by performing flexural vibration tests on graphite/epoxy beams. Dynamic behavior in the dry room-temperature state of 25°C (77°F) is contrasted with four elevated-temperature states: (1) 82°C (180°F), dry; (2) 60°C (140°F), moisture saturated; (3) 82°C (180°F), moisture saturated; and (4) 93°C (200°F), moisture saturated. The properties determined are an effective flexural modulus and damping for frequencies from 10 to 1000 Hz. Specimens are of four distinct ply layups manufactured from Narmco 5208/T300 unidirectional tape.

Overall, the modulus and damping results indicate that frequency effects are quite small in all cases. They are a bit greater for matrix-controlled modes of response at the higher frequencies. At the same temperature, damping increases with moisture saturation. For dry specimens, however, damping decreases with temperature.
Long-Life Damage Tolerant Jet Transport Structures
Authors: Goranson UG , Hall J , Maclin JR , Watanabe RT
Published: March 2009

Criteria and procedures used in commercial aircraft design over the last two decades have produced long-life damage tolerant structures with a credible safety record. This has been achieved through diligent attention to detail design, manufacturing, maintenance, and inspection procedures. Recent updates of federal regulations governing fatigue and fail-safe strength evaluation of transport category airplane structures and advancements in the capability to analyze damaged structure have spurred new technological developments. Adaptation of traditional fatigue and fracture mechanics technologies plus a large test and service experience data base have led to development of technology control methods suitable for nonspecialist engineers.

Detection of damage before it becomes dangerous is the ultimate control in ensuring damage tolerance throughout the economic service life of the structure. Traditional damage growth and residual strength evaluations fail to incorporate damage detection parameters which influence maintenance planning. New technology is under development for proper recognition of damage detection opportunities in a fleet of aircraft with possible multiple cracking events and subjected to a multitude of inspections. Emerging damage tolerance rating systems provide efficient measurements of inspection activities and permit coordinated manufacturer/operator/certifying agency actions necessary to ensure continued structural airworthiness of existing and future jet transport fleets.
Methodology for Evaluating Weight Savings from Basic Material Properties
Authors: Ekvall JC , Rhodes JE , Wald GG
Published: March 2009

Major payoffs of new aerospace structures in terms of weight savings, performance, and life-cycle cost are anticipated from successful development of advanced materials. To aid in development of new alloy systems a method has been developed for predicting weight savings resulting from material (property set) improvements for specific failure modes in aircraft structures. Material properties include density, modulus of elasticity, strength, fatigue, crack growth, fracture toughness, and stress corrosion resistance. Weight savings analysis includes consideration of the margins of safety for various failure modes that could affect the size of the aircraft structure. Results of analysis applicable to a carrier-based patrol aircraft and an advanced tactical fighter indicate a weight savings potential of up to 16 percent for advanced aluminum alloys.
Calcareous Soils of the Southwestern United States
Authors: Beckwith GH , Hansen LA
Published: March 2009

The origin, distribution, and engineering properties of calcareous soils of the southwestern United States are reviewed. The influence of climatic conditions on formation is discussed. A classification system is outlined in which detailed descriptions of soil masses and their discontinuities are made in test pits or trenches. Procedures of investigation which emphasize the use of standard penetration, plate bearing, and pressure-meter tests and seismic surveys are outlined along with bearing capacity and elastic settlement analysis methods. Typical geotechnical properties from in situ tests and settlement records are presented.
Geotechnical Properties of Two Calcareous Oozes
Authors: Valent PJ , Altschaeffl AG , Lee HJ
Published: March 2009

The geotechnical properties of two deep-sea calcareous oozes are discussed. The first ooze, a clayey silt with 56 to 75 percent calcium carbonate, was subjected to laboratory vane shear, one-dimensional compression, and triaxial shear testing. The void ratio-log pressure relationship obtained from one-dimensional compression tests, for a pressure increment ratio of 1, was found to be continuously plunging, a curve form possibly characteristic of the calcareous oozes. The failure envelope determined from triaxial shear tests defined a decreasing effective friction angle with increasing confining stress (34 deg, decreasing to 28 deg). Efforts toward establishing a connection between these phenomena and grain crushing in the sediment at engineering loads were not conclusive.

The second ooze, a fine sand-silt with 77 to 86 percent calcium carbonate, was tested both in-place (vane shear) and in the laboratory (vane shear and triaxial). In-place vane strengths are quite high, 10 to 30 kPa (1.5 to 4.5 psi), while laboratory vane strengths are near zero. The ooze exhibits high in-place vane strength sensitivities (5 to 10).
Unique Engineering Properties and Compression Behavior of Deep-Sea Calcareous Sediments
Authors: Demars KR
Published: March 2009

This study examines the individual particles comprising a typical deep-sea calcareous clay as a means of explaining their unique engineering properties and compression behavior. The scanning electron microscope is used to determine calcareous particle geometry, size, and packing, and the effect of one-dimensional compression on microstructure and particle fracture. The sediments examined in this study have carbonate contents of 40 to 90 percent, including 5 to 10 percent of sand-sized Foraminifera, the remainder being fine, silt-sized nannofossils. The Foraminifera and nannofossils are hollow and capable of storing large quantities of intraparticle water. When subjected to moderate compression stresses, the Foraminifera particles are susceptable to fracture and release intraparticle water, whereas the nannofossils exhibit minor fracturing or chipping at particle contact points. Carbonate contents should be routinely performed as an index property on deep-sea sediment specimens to determine the presence of hollow nannofossil and foram particles.
Geotechnical Properties and Behavior of Calcretes in South and South West Africa
Authors: Netterberg F
Published: March 2009

This paper reviews the geotechnical properties and behavior of calcretes (caliches) in South and South West Africa. Calcretes range in properties from those of loose soils to hard rock. Their unusual composition and origin convey upon them unusual geotechnical properties, limiting the applicability of some current ASTM and other description, classification, and test methods and specifications for bases, subbases, and surface courses.
Electrochemical Corrosion of an Aluminum Alloy in Cavitating Ethylene Glycol Solutions
Authors: Chance RL
Published: March 2009

Aluminum alloys that are used in engine cooling systems with high velocity fluids are particularly susceptible to damage by cavitation. Electrochemical methods were used successfully to determine the contribution of corrosion to the total metal damage caused by ultrasonically-induced cavitation. Measurements were made for an aluminum casting alloy immersed in hot ethylene glycol solutions, which were either well-inhibited or poorly inhibited against corrosion. Results of controlled-potential tests showed that the resistance of aluminum to cavitation damage in various media may be evaluated electrochemically, and that the magnitude of the effect of corrosion on cavitation damage can be as high as 75 percent of the total damage when cavitation is induced by ultrasonics. The metal potential, the corrosivity of the medium, and the inhibitor content of the ethylene glycol solution affect the nature and degree of cavitation damage.
Heat-Transfer Model for Fibrous Insulations
Authors: Bhattacharyya RK
Published: March 2009

A model has been developed that describes the insulation property of fibrous insulation. The assumptions necessary for the derivation and possible limitations are discussed.

Analysis of the model shows the effect of mean temperature and the effect of the insulation thickness on the effective thermal conductivity. The model provides a convenient way of predicting the thermal resistance at full thickness. Implementation of the technique, however, requires further tests with standardized equipment.

Further extensions of the model and modifications of the standard measuring techniques of the standard calibration specimen have been outlined. Areas requiring further research are indicated.
Sampling Faced Foam Insulation Board for Heat Flow Meter Thermal Performance Testing
Authors: Sherman M
Published: March 2009

A practical method is proposed for sampling large-dimension faced rigid foam plastic thermal insulation board in order to obtain a representative number of smaller-dimension test specimens for reproducibly measuring the board's thermal performance properties in conventional heat flow meter equipment. Using a statistical approach, six-specimen traverse sampling is shown to significantly reduce the required number of test specimens without inordinately increasing measurement error risk. Data are also provided which characterize the long-term protective benefits of aluminum foil facers in maintaining good thermal performance capability (aged k-factor).
Fibrous Glass Board as a Standard Reference Material for Thermal Resistance Measurement Systems
Authors: Siu MCI
Published: March 2009

Results of thermal measurements on over 300 pairs of fibrous glass board specimens, and statistical analysis of the data, are presented. This material is available as a Standard Reference Material (SRM) from the Office of Standard Reference Materials, National Bureau of Standards, Washington, D.C. 20234. Considerations are discussed for effective use of this SRM in the calibration of measurement systems such as the guarded hot-plate and heat flow meter apparatuses.