Fatigue Testing of Pipeline Welds and Heat-Affected Zones in Pressurized Hydrogen Gas.

Several welds and associated heat-affected zones (HAZs) on two API X70 and two API X52 pipes were tested to determine the fatigue crack growth rate (FCGR) in pressurized hydrogen gas and assess the area of the pipe that was most susceptible to fatigue when subjected to hydrogen gas. The relationship between FCGRs for welds and HAZs compared to base metal is discussed relative to local residual stresses, differences in the actual path of the crack, and hydrogen pressure effects.

Demonstration of a chamber for strain mapping of steel specimens under mechanical load in a hydrogen environment by synchrotron radiation.

We demonstrate a hydrogen gas chamber suitable for lattice strain measurements and capturing radiographs of a steel specimen under a mechanical load using high energy synchrotron x-rays. The chamber is suitable for static and cyclic mechanical loading. Experiments were conducted at the 1-ID-E end station of the Advanced Photon Source, Argonne National Laboratory.

A transatlantic perspective on 20 emerging issues in biological engineering.

Advances in biological engineering are likely to have substantial impacts on global society. To explore these potential impacts we ran a horizon scanning exercise to capture a range of perspectives on the opportunities and risks presented by biological engineering. We first identified 70 potential issues, and then used an iterative process to prioritise 20 issues that we considered to be emerging, to have potential global impact, and to be relatively unknown outside the field of biological engineering.

Chamber for mechanical testing in H with observation by neutron scattering.

A gas-pressure chamber has been designed, constructed, and tested at a moderate pressure (3.4 MPa, 500 psi) and has the capability of mechanical loading of steel specimens for neutron scattering measurements. The chamber will allow a variety of in situ neutron scattering measurements: in particular, diffraction, quasielastic scattering, inelastic scattering, and imaging.

Predicting Stability of Mild Cognitive Impairment (MCI): Findings of a Community Based Sample.

Background: Mild Cognitive Impairment (MCI) is a risk factor for Alzheimer's disease (AD) and other forms of dementia. However, much heterogeneity concerning neuropsychological measures, prevalence and progression rates impedes distinct diagnosis and treatment implications.

Objective: Aim of the present study was the identification of specific tests providing a high certainty for stable MCI and factors that precipitate instability of MCI in a community based sample examined at three measurement points.

Neural Correlates of Unsuccessful Memory Performance in MCI.

People with mild cognitive impairment (MCI) are at an elevated risk of developing Alzheimer's disease or other forms of dementia. Although the neural correlates of successful memory performance in MCI have been widely investigated, the neural mechanisms involved in unsuccessful memory performance remain unknown. The current study examines the differences between patients suffering from stable amnestic MCI with multiple deficit syndromes and healthy elderly controls in relation to the neural correlates of both successful and unsuccessful encoding and recognition.

Sensitivity Analysis of Fatigue Crack Growth Model for API Steels in Gaseous Hydrogen.

A model to predict fatigue crack growth of API pipeline steels in high pressure gaseous hydrogen has been developed and is presented elsewhere. The model currently has several parameters that must be calibrated for each pipeline steel of interest. This work provides a sensitivity analysis of the model parameters in order to provide (a) insight to the underlying mathematical and mechanistic aspects of the model, and (b) guidance for model calibration of other API steels.

Antihistamine induced blood oxygenation level dependent response changes related to visual processes during sensori-motor performance.

The histaminergic involvement in selective processes underlying its role in human sensori-motor performance is largely unknown. Recently, selective effects of central H₁-inverse agonism on sensory visual processes were observed in electrophysiological--but not behavioral data; a discrepancy suggested to result from speeded response-choice related processes. This study attempts to establish the effects on visual processes and identify putative compensatory mechanisms related to increased visual and response-choice task demands by assessing H₁-inverse agonism induced changes in blood oxygenation level dependent (BOLD) response.

Mild cognitive impairment: advantages of a comprehensive neuropsychological assessment.

Mild cognitive impairment (MCI) could be an auspicious candidate for an early marker of a beginning dementia. However, although MCI is accepted as a heterogeneous condition by now, performance testing or diagnosis is often based on a limited number of cognitive tests. Furthermore, there is still disagreement about the necessity to include subjective cognitive complaints as a diagnostic criterion.

Childhood maltreatment and migraine (part I). Prevalence and adult revictimization: a multicenter headache clinic survey.

Objectives: To examine the prevalence of childhood maltreatment and adult revictimization in migraineurs and the association with sociodemographic factors, depression and anxiety.

Background: Population and practice-based studies have demonstrated an association of childhood abuse and headache in adults, although further details on headache diagnoses, characteristics, and comorbid conditions are lacking. There are mounting data suggesting substantial impact of early maltreatment on adult physical and mental health.

Childhood maltreatment and migraine (part II). Emotional abuse as a risk factor for headache chronification.

Objectives: To assess in a headache clinic population the relationship of childhood abuse and neglect with migraine characteristics, including type, frequency, disability, allodynia, and age of migraine onset.

Background: Childhood maltreatment is highly prevalent and has been associated with recurrent headache. Maltreatment is associated with many of the same risk factors for migraine chronification, including depression and anxiety, female sex, substance abuse, and obesity.

Childhood maltreatment and migraine (part III). Association with comorbid pain conditions.

Objective: To evaluate in a headache clinic population the relationship of childhood maltreatment on the prevalence of pain conditions comorbid with migraine.

Background: Childhood maltreatment is highly prevalent and has been frequently associated with recurrent headache. The relationship of maltreatment and pain has, however, been a subject of some debate.

Allodynia in migraine: association with comorbid pain conditions.

Background: Cutaneous allodynia (CA) in migraine is a clinical manifestation of central nervous system sensitization. Several chronic pain syndromes and mood disorders are comorbid with migraine. In this study we examine the relationship of migraine-associated CA with these comorbid conditions.

Quantifying nonlinear anisotropic elastic material properties of biological tissue by use of membrane inflation.

Determination of material parameters for soft tissue frequently involves regression of material parameters for nonlinear, anisotropic constitutive models against experimental data from heterogeneous tests. Here, parameter estimation based on membrane inflation is considered. A four parameter nonlinear, anisotropic hyperelastic strain energy function was used to model the material, in which the parameters are cast in terms of key response features.

Posttraumatic stress disorder in migraine.

Objective: To evaluate the relative frequency of posttraumatic stress disorder (PTSD) in episodic migraine (EM) and chronic daily headache (CDH) sufferers and the impact on headache-related disability.

Background: Approximately 8% of the population is estimated to have PTSD. Recent studies suggest a higher frequency of PTSD in headache disorders.

Stiffening of the Extrapulmonary Arteries From Rats in Chronic Hypoxic Pulmonary Hypertension.

Changes in the compliance properties of large blood vessels are critical determinants of ventricular afterload and ultimately dysfunction. Little is known of the mechanical properties of large vessels exhibiting pulmonary hypertension, particularly the trunk and right main artery. We initiated a study to investigate the influence of chronic hypoxic pulmonary hypertension on the mechanical properties of the extrapulmonary arteries of rats.

Comparison of mechanical behavior among the extrapulmonary arteries from rats.

Results of comparative tests on pulmonary arteries from untreated Long-Evans rats are presented from three sections of the artery: the trunk, and the right and left main extrapulmonary arteries. Analyses were conducted looking for mechanical differences between the flow (longitudinal) and circumferential directions, between the right and left main arteries, and between each of the mains and the trunk. The mechanical properties of rat pulmonary arteries were obtained with a bubble inflation technique.

A microstructural hyperelastic model of pulmonary arteries under normo- and hypertensive conditions.

This work represents the first application of a statistical mechanics based microstructural orthotropic hyperelastic model to pulmonary artery mechanics under normotensive and hypertensive conditions. The model provides an analogy between the entangled network of long molecular chains and the structural protein framework seen in the medial layer, and relates the mechanical response at macro-level to the deformation (entropy change) of individual molecular chains at the micro-level. A finite element approach was adopted to implement the model.

Bubble-test method for synthetic and bovine vascular material.

A measurement system has been designed and constructed at NIST for the study of the mechanical properties of synthetic and bovine vascular materials. The measurement technique was validated on latex, where good agreement was found with the Neo-Hookean model. Measurements were also made on expanded polytetrafluoroethylene, which is commonly used for vascular grafts.

Responsiveness to G-CSF before leukopenia predicts defense to infection in high-dose chemotherapy recipients.

An active assessment of the host capacity to prevent infection during myelosuppression should be beneficial in patients receiving high-dose chemotherapy. A single dose of granulocyte colony-stimulating factor (G-CSF) (5 microg/kg) was given to 57 patients with multiple myeloma early after the completion of 85 high-dose chemotherapy (melphalan 200 mg/m2) courses. This provoked a highly variable white blood cell (WBC) peak after 12 to 14 hours.

Stress and strain in rat pulmonary artery material during a biaxial bubble test.

A biaxial bubble test has been designed to ascertain the mechanical properties of rat pulmonary arteries. The analytical procedure used to estimate stress and strain from the resulting test data is presented along with some analytical results. The bubble test was performed by loading a flat piece of rat pulmonary artery into a test fixture beneath a circular opening; the material was subsequently pressurized from below, producing a "bubble" of deformed material.

Comparison of strength properties of normotensive and hypertensive rat pulmonary arteries.

A series of tests were conducted to quantify the difference in the mechanical properties of normo- and hypertensive pulmonary arteries. A bubble-test design was employed to measure the biaxial properties of a segment of artery. The test results compare the properties at multiple orientations of the trunk, right, and left pulmonary arteries from normal (Control) and monocrotaline-treated male Long-Evans wild rats that ranged in age from 8 to 17 weeks old, along with some preliminary results from hypoxic Long-Evans knock-out rats.

An Experimental Method for Measuring Mechanical Properties of Rat Pulmonary Arteries Verified With Latex.

This paper describes a test method for measuring the mechanical properties of small, nonlinear membrane samples from a rat model for pulmonary hypertension. The size and nonlinearity of the pulmonary artery samples poses a challenge for developing a test method that will generate quality, reproducible data in the pressure range experienced by the hypertensive pulmonary artery. The experimental method described here has sufficient precision to yield a combined relative standard uncertainty of 4 %.

The CD19+ B-cell counts at peripheral blood stem cell mobilization determine different levels of tumour contamination and autograft purgability in low-grade lymphoma.

The tumour load of peripheral blood stem cell (PBSC) harvests and the outcome of ex vivo immunomagnetic B-cell purging was investigated in 19 patients with low-grade lymphoma. To quantify the tumour load, we combined fluorescence-activated cell sorting measurement of CD19+ B-cells and determination of the B-cell light chain ratio (LCR) with consensus complementarity-determining region III-polymerase chain reaction (CDRIII-PCR) and gene scan analysis. The number of tumour cells was calculated using B-cell extracts from the PBSCs.

The relationship between monoclonal myeloma precursor B cells in the peripheral blood stem cell harvests and the clinical response of multiple myeloma patients.

The aim of this study was to determine the presence of monoclonal myeloma precursor B cells in peripheral blood stem cell harvests and to investigate their role in the clinical outcome of multiple myeloma patients. A total of 39 multiple myeloma patients were treated with a sequential therapy including double high-dose melphalan therapy followed by a double transplant procedure. The apheresis products for the second transplant were purged using a panel of four or five different mouse monoclonal antibodies against B-cell antigens (CD10, CD19, CD20, CD22 and CD37).