bluuebunny/crossref_metadata_2025_split huggingface dataset:
Shear-Wave Ultrasonic Crack Inspection Tool Performance for Cracks Associated With Metal Loss
Authors: Scholte Mendoza Paola , Bott Steven , Hubert Yvan 
Published: November 2016

Shear-wave ultrasonic in-line tools are used for crack management in liquids pipelines. An ultrasonic pulse is generated, travels in the pipe wall and reflects on axially oriented artifacts that could be geometric or crack-like in nature. If several geometrical artifacts are present, detection and sizing efficiency of these ultrasonic inspection tools could be reduced. Cracking located within corrosion is one possible interacting set of geometrical artifacts that could affect in-line inspection (ILI) performance.
As part of continuous improvement, a comprehensive review of two thousand three hundred and thirty eight in-the-ditch measurements of cracking in corrosion were compared to crack ILI reported features in order to determine the tool performance in cases where cracks were associated with metal loss. Relationships of depth and predicted burst pressures were reviewed and compared to cracks not associated with metal loss. Additionally, field NDE results that had incomplete information in the ILI-NDE correlation files with indications of being potential defects were reviewed to examine the possibility of undocumented coincident cracking in metal loss that could represent an integrity threat. This paper summarizes the results and potential implications for management of cracking in corrosion using shear-wave ultrasonic crack ILI.
Restored Crossings: When and Where to Apply Stream Restoration Techniques to Protect Exposed Pipelines
Authors: Salas Dan , Steber Aaron 
Published: November 2016

Maintenance of existing rights-of-way often involve dealing with exposed pipelines near stream crossings. Streams often shift over time. This adjustment can lead to erosion of the streambed and streambanks, exposing pipelines or other infrastructure to threats such as hydraulic pressure, buoyancy, debris collisions, or pipe vibration and fatigue. Under these conditions, managers can be faced with relocating the pipe, performing localized streambank stabilization, or employing stream restoration techniques to provide long-term protection.
When localized stabilization is the preferred approach, selection of techniques is often determined by what will protect the pipeline without consideration of the stream context surrounding it. However, due to site conditions, manager preferences, and regulatory considerations, techniques from the disciplines of stream restoration and habitat enhancement can provide cost-effective alternatives to traditional hard-armoring by concrete or stone depending on the site context. Using past experience and a series of decision analysis tools, it was determined that geomorphic context should be factored as a foremost consideration when evaluating the most stable and cost effective approach to correcting exposed pipelines. One of the most critical factors in assessing the feasibility of stabilization options is the height and orientation of exposed pipes relative to the stream’s bankfull elevation.
Improvement of Pipeline Fatigue Life Estimation
Authors: Tiku Sanjay , Dinovitzer Aaron , Semiga Vlad , Piazza Mark , Jones Tom 
Published: November 2016

Fracture mechanics methodologies for calculating fatigue lives have been successfully applied by pipeline operators to estimate integrity reassessment intervals. Their application in the definition of pipeline system fatigue lives has been overly conservative in actual practice. The source and magnitude of the conservatism inherent in the calculated fatigue life estimates needs to be identified so operators have a better indicator of when reassessments should take place. The pipe life estimation is especially critical for Electric Resistance Weld (ERW) and Electric Flash Weld (EFW) pipeline systems with longitudinally oriented defects.
Prior work on improving fatigue life was initiated through studies completed by Pipeline Research Council International, Inc. (PRCI) to evaluate the sources of differences between fatigue life estimates produced by industry fatigue analysis software and different metallurgists. Two significant sources of conservatism in the fatigue life estimation process were identified: the fatigue crack growth rate (da/dN) and the bulging correction factor applied to axial surface flaws. The experimental and numerical simulation techniques considering the impact of these factors on rate of fatigue crack growth of pipeline axially oriented defects are described in this paper.
Finite element modeling was used to simulate pipe bulging in the presence of axial flaws. The effect of the pipe thickness, diameter and flaw geometry was compared with treatments included in existing defect assessment standards. The results illustrate that for longer and deeper flaws existing treatments over represent the local bending due to pipe wall bulging. This results in unnecessarily conservative (shorter) fatigue life estimates.
The crack growth rate (da/dN) was measured in a compact tension specimen material fatigue testing program. The test results included a range of ERW and EFW pipe materials with varying vintages and grades. The measured fatigue crack growth rate for the materials tested was found to be lower than that recommended by existing industry standards. This adds to the over conservatism of current approaches.
The numerical simulation and materials testing results and related recommendations presented in this paper are compared to existing codified treatments to quantify the level of conservatism inherent in the current state of practice. Recommendations are provided to enhance the precision and better manage conservatism in fatigue crack growth rate calculations. Increased accuracy serves to improve integrity management and would be of interest to pipeline operators, consultants and regulators.
A Finite Element Procedure to Model the Effect of Hydrostatic Testing on Subsequent Fatigue Crack Growth
Authors: Anderson Ted L. , Thorwald Greg V. 
Published: November 2016

Hydrostatic testing of pipelines that are subject to pressure cycling and fatigue damage can alter the intrinsic characteristics of flaws that survive the test. The effect is generally favorable, as test pressures well above the maximum operating pressure (MOP) can significantly reduce the subsequent rate of fatigue crack growth. The phenomenon is known as fatigue retardation, which is caused by crack closure due to compressive residual stresses created by plastic deformation during the hydrotest.
Fatigue retardation following an overload event is a well-known phenomenon in metallic structures, but there has been little or no effort to take advantage of this beneficial effect in pipelines. This paper presents a modeling procedure aimed at quantifying fatigue retardation following a hydrostatic test. A series of 3D elastic-plastic finite element simulations have been performed to model fatigue crack growth following a pressure test. The effect of test pressure and MOP on plasticity-induced crack closure was studied. The relative effect of fatigue retardation on remaining life was demonstrated with several examples. In some cases, the results were counter intuitive.
Application of Thermal Analysis Tool for Girth Welding Procedure Qualification
Authors: Dekhane Aditya , Wang Alex , Wang Yong-Yi , Quintana Marie 
Published: November 2016

The mechanical properties of welds are governed by the final microstructure that develops as an interaction between the chemical composition and cooling rates produced by welding thermal cycles. For welds in modern microalloyed thermomechanically controlled processed (TMCP) pipeline steels, the microstructure and mechanical properties can be extremely sensitive to cooling rates. The development and qualification of welding procedures to achieve targeted mechanical properties is often an iterative process. Accurate knowledge of welding thermal cycles and cooling rates as a function of welding parameters is valuable for optimization of welding process development.
This paper covers the development, validation, and application of a girth welding thermal analysis tool. The core of the tool is a numerical model that has a two-dimensional, axi-symmetrical finite element procedure to simulate the transient heat transfer processes both in the weld metal and the heat affected zone (HAZ). The tool takes welding parameters, pipe and bevel geometry, and thermal properties as inputs and predicts thermal cycles and cooling rates in weld metal and HAZ. The comparison of thermal cycles between experimental measurements and the model predictions show the tool was robust and accurate.
This tool is particularly effective in understanding the thermal history and resulting microstructure and mechanical properties of welds produced with high-productivity gas metal arc welding (GMAW), such as mechanized dual-torch pulsed gas metal arc welding (DT GMAW-P). The tool was used in optimization of development and qualification of welding procedures of a DT GMAW-P process under a tight time schedule. The actual welds were fabricated according to the optimized welding procedures followed by the mechanical testing of welds. Good agreement was found between the predicted tensile properties and those from experimental tests. The welding procedures were qualified within the tight time schedule by avoiding iterative trials, and reducing the cost associated with the making of trial welds and mechanical testing by approximately 50%. This tool has also been applied in the application of essential welding variables methodology (EWVM) for X80 and X70 linepipe steels [1, 2].
Future applications of the tools include the revamp of the approach to essential variables in welding procedure qualification. In particular, the parameters affecting cooling rates may be “bundled” together towards the one critical factor affecting weld properties, i.e., cooling rate. The individual parameters may be varied beyond the limits in the current codes and standards as long as their combined effects make the cooling rate stay within a narrow band. It is expected that the same framework of approaches to GMAW processes can be extended other welding processes, such as FCAW and SMAW.
Local attenuation curve optimization framework for high quality perfusion maps in low‐dose cerebral perfusion CT
Authors: Van Nieuwenhove Vincent , Van Eyndhoven Geert , Batenburg K. Joost , Buls Nico , Vandemeulebroucke Jef , De Beenhouwer Jan , Sijbers Jan 
Published: November 2016

Purpose:Cerebral perfusion x‐ray computed tomography (PCT) is a powerful tool for noninvasive imaging of hemodynamic information throughout the brain. Conventional PCT requires the brain to be imaged multiple times during the perfusion process, and hence radiation dose is a major concern. The authors propose a PCT reconstruction algorithm that allows for lowering the dose while maintaining a high quality of the perfusion maps. It relies on an accurate estimation of the arterial input function (AIF), which in turn depends on the quality of the attenuation curves in the arterial region.Methods:The authors propose the local attenuation curve optimization (LACO) framework. It accurately models the attenuation curves inside the vessel and arterial regions and optimizes its shape directly based on the acquired x‐ray projection data.Results:The LACO algorithm is extensively validated with simulation and real clinical experiments. Quantitative and qualitative results show that our proposed approach accurately estimates the vessel and arterial attenuation curves from only few x‐ray projections. In contrast to conventional approaches, where the AIF is estimated based on the reconstructed images, our method computes an optimal AIF directly based on the projection data, resulting in far more accurate perfusion maps.Conclusions:The LACO algorithm allows estimating high quality perfusion maps in low dose scanning protocols.
Computer aided prognosis for cell death categorization and prediction in vivo using quantitative ultrasound and machine learning techniques
Authors: Gangeh M. J. , Hashim A. , Giles A. , Sannachi L. , Czarnota G. J. 
Published: November 2016

Purpose:At present, a one‐size‐fits‐all approach is typically used for cancer therapy in patients. This is mainly because there is no current imaging‐based clinical standard for the early assessment and monitoring of cancer treatment response. Here, the authors have developed, for the first time, a complete computer‐aided‐prognosis (CAP) system based on multiparametric quantitative ultrasound (QUS) spectroscopy methods in association with texture descriptors and advanced machine learning techniques. This system was used to noninvasively categorize and predict cell death levels in fibrosarcoma mouse tumors treated using ultrasound‐stimulated microbubbles as novel endothelial‐cell radiosensitizers.Methods:Sarcoma xenograft tumor‐bearing mice were treated using ultrasound‐stimulated microbubbles, alone or in combination with x‐ray radiation therapy, as a new antivascular treatment. Therapy effects were assessed at 2–3, 24, and 72 h after treatment using a high‐frequency ultrasound. Two‐dimensional spectral parametric maps were generated using the power spectra of the raw radiofrequency echo signal. Subsequently, the distances between “pretreatment” and “post‐treatment” scans were computed as an indication of treatment efficacy, using a kernel‐based metric on textural features extracted from 2D parametric maps. A supervised learning paradigm was used to either categorize cell death levels as low, medium, or high using a classifier, or to “continuously” predict the levels of cell death using a regressor.Results:The developed CAP system performed at a high level for the classification of cell death levels. The area under curve of the receiver operating characteristic was 0.87 for the classification of cell death levels to both low/medium and medium/high levels. Moreover, the prediction of cell death levels using the proposed CAP system achieved a good correlation (r = 0.68,  p < 0.001) with histological cell death levels as the ground truth. A statistical test of significance between individual treatment groups with the corresponding control group demonstrated that the predicted levels indicated the same significant changes in cell death as those indicated by the ground‐truth levels.Conclusions:The technology developed in this study addresses a gap in the current standard of care by introducing a quality control step that generates potentially actionable metrics needed to enhance treatment decision‐making. The study establishes a noninvasive framework for quantifying levels of cancer treatment response developed preclinically in tumors using QUS imaging in conjunction with machine learning techniques. The framework can potentially facilitate the detection of refractory responses in patients to a certain cancer treatment early on in the course of therapy to enable switching to more efficacious treatments.
Trained Immunity and Susceptibility to HIV
Authors: Derrick Steven C. 
Published: November 2016

ABSTRACT

In this issue of
Clinical and Vaccine Immunology
, K. Jensen et al. (Clin Vaccine Immunol 24:e00360-16, 2017,
https://doi.org/10.1128/CVI.00360-16
) describe a dual-purpose attenuated
Mycobacterium tuberculosis-
simian immunodeficiency virus vaccine (AMTB-SIV). Interestingly, immunized infant macaques required fewer oral exposures to SIV to become infected relative to nonimmunized animals. The authors hypothesized that augmented susceptibility to SIV was due to activation of CD4
+
T cells through trained immunity. This commentary explores the possible relationship between trained immunity, enhanced CD4 T cell responses, and increased susceptibility to human immunodeficiency virus (HIV).
Detection and Differentiation of Leishmania spp. in Clinical Specimens by Use of a SYBR Green-Based Real-Time PCR Assay
Authors: de Almeida Marcos E. , Koru Ozgur , Steurer Francis , Herwaldt Barbara L. , da Silva Alexandre J. 
Published: November 2016

ABSTRACTLeishmaniasis in humans is caused byLeishmaniaspp. in the subgeneraLeishmaniaandViannia. Species identification often has clinical relevance. Until recently, our laboratory relied on conventional PCR amplification of the internal transcribed spacer 2 (ITS2) region (ITS2-PCR) followed by sequencing analysis of the PCR product to differentiateLeishmaniaspp. Here we describe a novel real-time quantitative PCR (qPCR) approach based on the SYBR green technology (LSG-qPCR), which uses genus-specific primers that target the ITS1 region and amplify DNA from at least 10Leishmaniaspp., followed by analysis of the melting temperature (Tm) of the amplicons on qPCR platforms (the Mx3000P qPCR system [Stratagene-Agilent] and the 7500 real-time PCR system [ABI Life Technologies]). We initially evaluated the assay by testing referenceLeishmaniaisolates and comparing the results with those from the conventional ITS2-PCR approach. Then we compared the results from the real-time and conventional molecular approaches for clinical specimens from 1,051 patients submitted to the reference laboratory of the Centers for Disease Control and Prevention forLeishmaniadiagnostic testing. Specimens from 477 patients tested positive forLeishmaniaspp. with the LSG-qPCR assay, specimens from 465 of these 477 patients also tested positive with the conventional ITS2-PCR approach, and specimens from 10 of these 465 patients had positive results because of retesting prompted by LSG-qPCR positivity. On the basis of theTmvalues of the LSG-qPCR amplicons from reference and clinical specimens, we were able to differentiate four groups ofLeishmaniaparasites: theVianniasubgenus in aggregate; theLeishmania(Leishmania)donovanicomplex in aggregate; the speciesL. (L.)tropica; and the speciesL. (L.)mexicana,L. (L.)amazonensis,L. (L.)major, andL. (L.)aethiopicain aggregate.
Enterovirus 71 3C Promotes Apoptosis through Cleavage of PinX1, a Telomere Binding Protein
Authors: Li Jing , Yao Yunfang , Chen Yu , Xu Xiao , Lin Yongquan , Yang Zhilong , Qiao Wentao , Tan Juan 
Published: November 2016

ABSTRACTEnterovirus 71 (EV71) is an emerging pathogen causing hand, foot, and mouth disease (HFMD) and fatal neurological diseases in infants and young children due to their underdeveloped immunocompetence. EV71 infection can induce cellular apoptosis through a variety of pathways, which promotes EV71 release. The viral protease 3C plays an important role in EV71-induced apoptosis. However, the molecular mechanism responsible for 3C-triggered apoptosis remains elusive. Here, we found that EV71 3C directly interacted with PinX1, a telomere binding protein. Furthermore, 3C cleaved PinX1 at the site of Q50-G51 pair through its protease activity. Overexpression of PinX1 reduced the level of EV71-induced apoptosis and EV71 release, whereas depletion of PinX1 by small interfering RNA promoted apoptosis induced by etoposide and increased EV71 release. Taken together, our study uncovered a mechanism that EV71 utilizes to promote host cell apoptosis through cleavage of cellular protein PinX1 by 3C.IMPORTANCEEV71 3C plays an important role in processing viral proteins and interacting with host cells. In this study, we showed that 3C promoted apoptosis through cleaving PinX1, a telomere binding protein, and that this cleavage facilitated EV71 release. Our study demonstrated that PinX1 plays an important role in EV71 release and revealed a novel mechanism that EV71 utilizes to induce apoptosis. This finding is important in understanding EV71-host cell interactions and has potential impact on understanding other enterovirus-host cell interactions.
Activity-dependent formation and location of voltage-gated sodium channel clusters at a CNS nerve terminal during postnatal development
Authors: Xu Jie , Berret Emmanuelle , Kim Jun Hee 
Published: November 2016

In auditory pathways, the precision of action potential (AP) propagation depends on axon myelination and high densities of voltage-gated Na (Nav) channels clustered at nodes of Ranvier. Changes in Nav channel expression at the heminode, the final node before the nerve terminal, can alter AP invasion into the presynaptic terminal. We studied the activity-dependent formation of Nav channel clusters before and after hearing onset at postnatal day 12 in the rat and mouse auditory brain stem. In rats, the Nav channel cluster at the heminode formed progressively during the second postnatal week, around hearing onset, whereas the Nav channel cluster at the nodes was present before hearing onset. Initiation of heminodal Nav channel clustering was correlated with the expression of scaffolding protein ankyrinG and paranodal protein Caspr. However, in whirler mice with congenital deafness, heminodal Nav channels did not form clusters and maintained broad expression, but Nav channel clustering was normal at the nodes. In addition, a clear difference in the distance from the heminodal Nav channel to the calyx across the mediolateral axis of the medial nucleus of the trapezoid body (MNTB) developed after hearing onset. In the medial MNTB, where neurons respond best to high-frequency sounds, the heminodal Nav channel cluster was located closer to the terminal than in the lateral MNTB, where neurons respond best to low-frequency sounds. Thus sound-mediated neuronal activities are potentially associated with the refinement of the heminode adjacent to the presynaptic terminal in the auditory brain stem. NEW & NOTEWORTHY Clustering of voltage-gated sodium (Nav) channels and their distribution along the axon, specifically at the unmyelinated axon segment next to the nerve terminal, are essential for tuning propagated action potentials. Nav channel clusters near the nerve terminal and their location as a function of neuronal position along the mediolateral axis are controlled by auditory inputs after hearing onset. Thus sound-mediated neuronal activity influences the tonotopic organization of Nav channels at the nerve terminal in the auditory brain stem.