bluuebunny/crossref_metadata_2025 huggingface dataset:
Classification of Flow Patterns in Angled T-Junctions for the Evaluation of High Cycle Thermal Fatigue
Authors: Qian Shaoxiang , Frith James , Kasahara Naoto
Published: January 2011

Temperature fluctuations generated by the mixing of hot and cold streams at T-junctions can cause high cycle thermal fatigue failure. One of the important parameters for determining the degree of thermal fatigue damage is related to the flow patterns downstream of the mixing junction. Many papers have been published identifying the characteristic equations for classifying the flow patterns at the T-junctions, which have been shown to be related to the momentum ratios between the main pipe flow and the branch pipe flow. The flow patterns and governing equations studied in the past are only applicable to 90-degree tee junctions (T-junctions). The intention of this paper is to extend the work of others to include angled tee junctions other than 90 degrees (Y-junctions). Y-junctions especially with 45-degree angle are also used in the chemical and refinery plants of our concern for lowering the pressure drop in the mixing zone and weakening the impingement of the branch pipe stream against the main pipe. This paper presents the proposal for a set of extended characteristic equations for classifying the flow patterns in mixing tees which can be applied to all angles of tee junctions. The modified characteristic equations have been verified using computational fluid dynamics (CFD) simulations. Models with branch angles other than 90 degrees have been used to confirm the robustness and validity of the modified equations. The effect of the pressure drop caused by the varying opening sizes has been shown to play only a minor role in determining the overall flow patterns, with the key variables being the velocity ratio and the interaction area between the flow in the main pipe and the jet exiting from the branch pipe. The results have also highlighted that the angle of the branch pipe has significant impact on increasing the velocity ratio range for the less damaging deflecting jet flow pattern, which is an important finding that could be used to extend the current design options for piping systems where high cycle thermal fatigue may be a concern.
Vibration Suppression of Flexible Structures Utilizing Internal Resonance of Liquid Sloshing in a Nearly Square Tank
Authors: Ikeda Takashi
Published: January 2011

This paper proposes a new idea to utilize the internal resonance of two different sloshing modes in a nearly square tank when used as a tuned liquid damper (TLD). This idea results in achieving higher efficiency of vibration suppression for flexible structures subjected to horizontal harmonic excitation. Namely, the two sloshing modes (1, 0) and (0, 1) in a nearly square tank are degenerated and hence their natural frequencies are nearly equal with each other. Because the two predominant sloshing modes are nonlinearly coupled, internal resonance is expected to occur. Galerkin’s method is used to determine the modal equations of motion for liquid sloshing. Then, van der Pol’s method is used to determine the expressions of the frequency response curves. Frequency response curves and bifurcation sets are numerically calculated. From these results, the optimal values of the size and instillation angle of the tank can be determined in order to achieve maximum efficiency of vibration suppression in a flexible structure. Experiments confirmed the validity of the theoretical analysis.
Application of CFD to Solve Difficult Industry Thermal Stress Problems
Authors: Dewees David J.
Published: January 2011

Temperature variation is the source of load in pure thermal stress analysis; thus, meaningful prediction of temperatures in a structure is critical to analysis success. Temperature measurement and standard heat transfer correlations should be the basis of the majority of heat transfer analysis. However, there is a class of problems where temperature measurement is not possible or feasible and standard heat transfer correlations are not applicable. For cases such as these, computational fluid dynamics (CFD) provides a valuable tool to better assess the fluid/thermal behavior in complex configurations, and thus the resulting temperature gradients within a structure. Several practical examples that illustrate the value of CFD in thermal stress analysis are detailed in this paper.
Analysis Method of Failure Likelihood on Pressure Equipment With Combined Action of Multi-Failure Mechanism
Authors: Chen Xuedong , Ai Zhibin , Yang Tiecheng , Hu Jiushao , Cheng Chuanqing
Published: January 2011

Since 2003, we have conducted a lot of researches on risk based assessment technology in China according to standards API 581, API 571 etc., mastered the risk distribution conditions of in-service pressure equipments covering all kinds of units of about 80 large-scale oil refinery plants, chemical plants and chemical fertilizer plants in China, and formed the failure trees and technical guide documents for RBI of typical petrochemical units fit to Chinese national conditions. However, we find there are interactions of various failure modes and mechanisms of many petrochemical equipment during their actual running due to the diversity of corrosive media and the complexity of influential factors in the process of risk assessment implementation process, which has not been taken into account in the existing API 581, if we cannot determine the possible dominant failure modes and failure mechanisms as well as influential factors of secondary mechanisms in the actual service environment of pressure equipment, the risk assessment analysis results obtained tend to have big difference from actual conditions. In this paper, researches are conducted with respect to the judgment methods of dominant mechanisms in case of joint action of multiple failure mechanisms of pressure equipment and influential law of secondary mechanisms in several typical complicated medium environment of petrochemical enterprises based on the survey and analysis of failure accidents, risk assessment and experimental research of pressure equipment, and suggestions on improvement with respect to failure likelihood calculation methods in risk assessment in API 581 are given.
Models for Use in Probabilistic Pipe Rupture Assessment Code Development
Authors: Erickson Marjorie A. , Kirk Mark T. , Rathbun Howard J.
Published: January 2011

US Nuclear Regulatory Commission (USNRC) Standard Review Plan (SRP) 3.6.3, describes the current methodology for leak-before-break (LBB) piping safety assessment. Specifically, it describes a deterministic assessment procedure that can be used to demonstrate compliance with the 10CFR50 Appendix-A, General Design Criterion 4 (GDC-4) requirement that the primary system pressure piping exhibit an extremely low probability of rupture. However, SRP 3.6.3 does not permit assessment of piping systems with active degradation mechanisms, even though it is known that primary water stress corrosion cracking (PWSCC) has occurred in systems that have been granted LBB exemptions to remove pipe-whip restraints. To address this need, a program is being conducted with the long-term goal of developing a probabilistic assessment tool that can be used to directly demonstrate compliance with 10CFR50 Appendix–A, GDC-4, a tool that would account for the effects of both active degradation mechanisms and the mitigation activities that are being undertaken to address this degradation. This program has been termed “xLPR” as its goal is to demonstrate an eXtremely Low Probability of Rupture in pressure boundary piping systems. This methodology augments current LBB assessment models (leak rate and crack stability models) through the addition of best estimate models describing the initiation and propagation of flaws due to the various degradation mechanisms (fatigue, PWSCC, intergranular stress corrosion cracking (IGSCC), etc.), inspection models, and mechanical and chemical mitigation/remediation models that describe changes in stress state, pipe material and environment caused by mitigation/remediation efforts. Models currently used in LBB assessment will be updated, or replaced, with best estimate, probabilistic models, including those for leak rate and crack stability assessment. All models should account for the full distribution of input variables (where known) in order to account for both epistemic and aleatory uncertainties in as detailed a manner as feasible. This paper summarizes the structure and current activities of the Modeling Task Group within the framework of the overall xLPR Project, and the methodology used to select and develop the models for the xLPR Pilot Study. Preliminary information on the various models chosen for the Pilot Study, and how they are linked within the structure of the overall xLPR probabilistic code, is also provided.
Slitting and Contour Method Residual Stress Measurements in an Edge Welded Beam
Authors: Hosseinzadeh Foroogh , Bouchard P. John , Toparli M. Burak
Published: January 2011

Welding is known to introduce complex three-dimensional residual stresses of substantial magnitude into pressure vessels and pipe-work. For safety-critical components, where welded joints are not stress-relieved, it can be of vital importance to quantify the residual stress field with high certainty in order to perform a reliable structural integrity assessment. Finite element modeling approaches are being increasingly employed by engineers to predict welding residual stresses. However, such predictions are challenging owing to the innate complexity of the welding process [1]. The idea of creating weld residual stress benchmarks against which the performance of weld modeling procedures and practitioners can be evaluated is gaining increasing acceptance. A stainless steel beam 50 mm deep by 10 mm wide, autogenously welded along the 10 mm edge, is a candidate residual stress simulation benchmark specimen that has been studied analytically and for which neutron and synchrotron diffraction residual stress measurements are available. The current research was initiated to provide additional experimental residual stress data for the edge-welded beam by applying, in tandem, the slitting and contour residual stress measurement methods. The contour and slitting results were found to be in excellent agreement with each other and correlated closely with published neutron and synchrotron residual stress measurements when differences in gauge volume and shape were accounted for.
Effect of Nitrogen on Hydrogen Embrittlement of Austenitic Stainless Steels Based on Type 316LN
Authors: Imade Masaaki , Zhang Lin , An Bai , Iijima Takashi , Fukuyama Seiji , Yokogawa Kiyoshi
Published: January 2011

The effect of nitrogen on hydrogen gas embrittlement (HGE) in 1 and 70 MPa hydrogen and internal reversible hydrogen embrittlement (IRHE) of austenitic stainless steels of 17Cr11Ni2Mo(0.4 in max.)N alloys, based on type 316LN, was investigated by slow strain rate technique tests at room temperature in comparison with the effect of Ni on HGE and IRHE of Ni-added type 316 stainless-steel-alloys. For the nitrogen-added alloys, HGE and IRHE decreased with increasing nitrogen content, where α′ martensitic transformation occurred. HGE was not observed but IRHE was observed above the nitrogen content, where austenite is completely stabilized by nitrogen. Hydrogen-induced fracture related to the strain-induced α′ martensite structure was observed in HGE specimens and that together with brittle transgranular fracture was observed in IRHE specimens. HGE of the nitrogen-added alloys is larger than that of the Ni-added alloys in the Nieq range, where α′ martensitic transformation occurred. No HGE was observed in both the nitrogen-added alloys and the Ni-added alloys, but IRHE was observed in not the Ni-added alloys but the nitrogen-added alloys above the Nieq, where no martensite is identified in both alloys. It is discussed that the α′ martensite and the austenite of the nitrogen-added alloys were more sensitive to HGE or IRHE than those of the Ni-added alloys.
A Comparison of Residual Stresses in Single-Pass and Multipass SA508 Steel Welds
Authors: Francis J. A. , Mark A. F. , Turski M. , Bate S. K. , Hofmann M. , Withers P. J.
Published: January 2011

The safe operation of a power plant is contingent on the integrity of its welded joints. In turn, the performance of these welded joints is strongly influenced by the residual stresses that remain after fabrication and, where applicable, post-weld heat treatment operations. It is thus critical that careful consideration is given to the influence of weld residual stresses on plant integrity at the design stage, as well as during subsequent service. Since it is generally difficult to measure weld residual stresses in thick-walled components, numerical models are employed to make predictions. Such models, however, will be limited by our understanding of material behaviour, particularly in the case of multipass welds, which involve several complex thermo-mechanical cycles. Here, we report on neutron diffraction measurements, which enable the residual stresses for a single weld bead deposited on to a 20 mm thick SA508 steel plate to be compared with those in an 8-pass groove weld. The same low-carbon (SD3) filler metal was used in the manufacture of both types of specimen. Interestingly, the residual stress distributions for each type of specimen were found to be very similar. This suggests that cyclic hardening effects did not play a decisive role in determining the final residual stress distribution within the multipass weld.
Coupled Creep Fatigue Analysis on 2-1/4 Cr-1Mo-V Pressure Components Per Code Case 2605
Authors: Zhao Mingxin
Published: January 2011

Vanadium modified or 2 1/4Cr-1Mo-V materials, including SA-182 F22V, SA-336 F22V, SA-541 Type D Class 4a, and SA-832 Grade 22V, are commonly used in pressure vessels or reactors with operating temperatures in the creep range and under cyclic loading conditions. The expected equipment service life due to fatigue will be affected by accumulated creep damage, which may no longer be ignored at higher operating temperatures. Coupled fatigue and creep damages become a crucial factor in evaluating pressure components’ service conditions. ASME B&PV Code Case 2605 outlined a procedure and acceptance criteria for conducting such analysis. This study reviews the background information on fatigue evaluation in the creep range, and presents a fatigue analysis coupled with creep damage on a reactor nozzle structure using finite element method as an example and practical application of the code case. Detailed implementations, analysis results, and recommendations are demonstrated and discussed.
Prediction of Relaxation Property for Long Term in Bolted Flange Joints Based on Viscoelasticity Model of Gasket
Authors: Yamaguchi Atsushi , Tsuji Hirokazu , Honda Takashi
Published: January 2011

Creep/relaxation occurs when gaskets for bolted flange joints are used over extended periods. Creep/relaxation of gaskets may cause leakage of an internal fluid from the joints. In order to prevent leakage of a contained fluid from flange joints, it is important to establish a method for the prediction of gasket creep or stress relaxation. In the present study, the relaxation behavior of the axial bolt force was measured in order to estimate creep/relaxation of gaskets by referencing the ASTM F-38 test method [1]. The tests were accomplished at room temperature over a period of 240 hours (10 days). The strain behavior of gaskets was obtained using the viscoelasticity model and the finite element (FE) model of the test equipment based on the ASTM F-38 test method. In addition, the creep strain behavior of gaskets obtained through finite element analysis (FEA) and applied to gaskets in the FE model of the bolted flange joints, and the stress relaxation in the bolted flange joints were estimated over the long term. In the FEA of the bolted flange joints, the relaxation behavior of the axial bolt force that includes internal pressure load was predicted using the creep strain behavior of the gasket. Then, the radial gasket stress is investigated for tightening, for internal pressure load and for stress relaxation. It was found that the radial stress of the gaskets approaches uniformity, and the effect of flange rotation in the bolted flange joint decreases due to the creep strain behavior of the gaskets.
A Stochastic Approach of Thermal Fatigue Crack Growth (LEFM) in Mixing Tees
Authors: Radu Vasile , Paffumi Elena
Published: January 2011

The assessment of fatigue crack growth due to turbulent mixing of hot and cold coolants presents significant challenges, in particular to determine the thermal loading spectrum. Thermal striping is defined as a random temperature fluctuation produced by incomplete mixing of fluid streams at different temperatures, and it is essentially a random phenomenon in a temporal sense. The objective of this work is to develop a stochastic model to assess thermal fatigue crack growth in mixing tees, based on the power spectral density (PSD) of the temperature fluctuation at the inner pipe surface. Based on the analytical solution for temperature distribution through the wall thickness, obtained by means of Hankel transform, a frequency temperature response function is proposed, in the framework of single-input, single-output (SISO) methodology from random noise/signal theory under sinusoidal input. For the elastic thermal stresses distribution solutions, the magnitude of the frequency response function is first derived and checked against the prediction by FEA. The frequency response of the stress intensity factor (SIF) is obtained by a polynomial fitting of the stress profiles through the wall thickness at various instants of time. The variability in load is given by the statistical properties of thermal spectrum. The temperature spectrum is assumed to be given as a stationary normalized Gaussian narrow-band stochastic process, with constant PSD for a defined range of frequencies. The connection between SIF’s PSD and temperature’s PSD is assured with SIF frequency response function modulus. The frequency of the peaks of each magnitude for KI, which is supposed to be a stationary narrow-band Gaussian process, is characterized by the Rayleigh distribution, and, consequently, the expected value of crack growth rate in respect to cycles is obtained. The probabilities of failure are estimated by mean of the Monte Carlo methods considering a limit state function, which is based on the developed stochastic model. The results of the stochastic approach of thermal fatigue crack growth in mixing tees is completed with probabilistic input to account for the variability in the material characteristics, and finally an application is given to obtain the probability of mixing tees piping failure as function of time reference period.
Classification Method in Chinese Supervision Regulation on Safety Technology for Stationary Pressure Vessel
Authors: Wu Linlin , Shou Binan , Xie Tiejun , Chen Zhaohui , Xu Ping
Published: January 2011

Pressure vessels, which are widely used in various industries, have different levels of hazards. In order to provide different technical requirements for vessels with different levels of hazards, classification of pressure vessels is necessary and supervision and administration should be carried out by category. The aim of this paper is to introduce a simple and rational classification method presented in the new version of Chinese Supervision Regulation on Safety Technology for Stationary Pressure Vessel, which specifies that the stationary pressure vessels should be classified according to the design pressure, volume, and fluid type. The classification methods of European Union and Australia are also described in this paper.
A Study on Behavior of Mixed Mode Fatigue Crack Growth of Spiral Welding Part Under Bending Load
Authors: Choi Jung-Hun , Kim Il-Hwan , Koo Jae-Mean , Seok Chang-Sung
Published: January 2011

Manufacturing of large scale steel pipes in a nuclear power plant, offshore structures and a petroleum chemical plant, etc., a spiral welding method is mainly used. Such a welding part generally has several types of defect such as an undercut, a pit and a crack and in many cases, it finally reaches the failure by crack growth from these. The linear elastic fracture mechanics has been applied to a study on fatigue crack growth of welding parts, that is, as the weld, the heat affected zone (HAZ) and the base metal part in a large scale steel pipe by several reachers. However, since such studies are mainly the results by a standard specimen under uniaxial tensile load, they are different from the fatigue crack growth of a real large scale steel pipe under multiaxial load. In this study, we performed the evaluation for the characteristics of the mixed mode fatigue crack growth behavior of a spiral welding part in a real large scale steel pipe under bending load.
Application of Plastic Region Bolt Tightening to Flange Joint Assembly: Behavior of Compact Flanged Joint Subjected to Thermal Load
Authors: Kaneda Shinobu , Shimizu Yoshiyasu , Nagata Satoshi , Tsuji Hirokazu
Published: January 2011

In the past study the plastic region tightening has been applied to the compact flange joint and its advantages have been demonstrated. However, behavior of the compact flange joint subjected to the thermal load is not investigated. There are reduction of the gasket stiffness, the flange rotation, and difference in the thermal expansion among the members making up the flange joint. It is well known that these problems cause the change in axial bolt force. The present paper describes the behavior of the compact flange joint subjected to the thermal load under the plastic region tightening. Since there is a difference in temperature between the compact flange joint and the bolts, the axial bolt force increases as the temperature of the internal fluid increases. The additional axial bolt force is positive when the thermal loads are applied to the compact flange joint. However, the additional axial bolt force was approximately 3% of the bolt yield force at maximum and the bolt had a sufficient margin for the allowable limit. Additionally, the load factor depends on the change in the elastic modulus due to change in temperature of the internal fluid.
Coalescence of Complex Cracks in Ex-Service Carbon Steel Pipe Bends During Burst Pressure Tests
Authors: Duan Xinjian , Kozluk Michael J. , Gendron Tracy , Slade John
Published: January 2011

This paper presents burst pressure tests of two ex-service, 2 1/2-inch, SA-106 Grade B pipe bends with multiple part-through-wall axial cracks. The two pipes tested were sections of outlet feeders that were removed from the Point Lepreau Generating Station after 18.6 and 19.5 effective full-power years of service. The field of cracks was tightly distributed in the longitudinal and transverse directions of pipe bends on both inside surface and outside surfaces. The total length of the crack fields were 40 mm and 100 mm, respectively. The deepest crack was 73% through-wall. The burst pressure tests were performed at 90°C. The failure pressure was more than 4 times the design pressure. Post-test metallurgical examinations revealed mixed mode failures on the main fracture surface. The failure of the specimens was controlled by local plastic collapse of the ligaments of a small number of the deepest cracks in the field of cracks.
On the Use of Theory of Rings on Non-Linear Elastic Foundation to Study the Effect of Bolt Spacing in Bolted Flange Joints
Authors: Do Tan Dan , Bouzid Abdel-Hakim , Dao Thien-My
Published: January 2011

Bolted flange joints are extensively used to connect pressure vessels and piping equipment together. They are simple structures that offer the possibility of disassembly. However, they often experience leakage problems due to a loss of tightness as a result of a non-uniform distribution of gasket contact stresses in the radial and circumferential direction. Many factors contribute to such a failure; the flange and gasket stiffness and bolt spacing design combination being one of them. In our recent paper the effects of bolt spacing was investigated based on the theory of circular beams resting on a linear elastic foundation [1]. This paper is an extension of the work in which an analytical solution based on the true gasket non-linear behavior is developed. The study focuses on the distribution of the gasket contact stress of two large diameter flanges namely a 52 and a 120 in heat exchanger flanges. The non-linear gasket behavior solution is compared to the FEA and the linear gasket behavior solution for evaluation and validation.
Development of Initial Input Parameters for a Probabilistic Pipe Rupture Assessment Code for Nuclear Reactor Coolant Pressure Boundary Leak-Before-Break Analyses
Authors: Focht Eric M. , DeBoo Guy
Published: January 2011

The U.S. Nuclear Regulatory Commission (NRC) and the Electric Power Research Institute (EPRI) entered into a cooperative agreement to develop a modular computer code for determining the probability of rupture of reactor coolant pressure boundary piping. The goal of xLPR project (Extremely Low Probability of Rupture), as it is known, is to develop a flexible modular code that satisfies the assessment methodology in the NRC Standard Review Plan (SRP) 3.6.3 leak-before-break analysis. The NRC SRP 3.6.3 provides guidance on satisfying Title 10 of the Code of Federal Regulations Part 50 (10 CFR Part 50) Appendix A, General Design Criteria 4 that requires primary system pressure piping to exhibit an extremely low probability of rupture. The initial phase of the xLPR project is the Pilot Study where the base structure of the code will be developed and tested on a known case. The Pilot Study version of the xLPR code consists of an alpha version where proxy modules and inputs are used and a beta version where the state-of-the art modules and inputs are used. This paper will discuss the input parameters used for the alpha xLPR code.
On the Creep Rupture Prediction of Composite Pressure Vessels
Authors: Schulz Michael
Published: January 2011

This article illustrates a concept of predicting the time dependent deformation and creep rupture strength of carbon fibre reinforced plastics (CFRP). In the presented concept the viscoelastic behaviour of the resin is determined by creep rupture tests at different temperature and load levels. Out of the experiments the relaxation spectrum of the resin is modelled including the spread. With the help of the classical rule of mixture and a modified classical laminate theory the minimum strain rate for the composite will be determined. The results will be compared to experimental data. Furthermore the Monkman-Grant approach is used to determine the time-to-failure strain-rate relation. Therefore an elastic solution of the classical laminate theory is used including Puck’s failure criteria to compute the Monkman-Grant relation. A Monte Carlo Simulation will be done to include the spread of the Monkman-Grant relation. The results will be compared to experimental results of unidirectional specimens. Finally it will be explained how the lifetime of a pressure vessel can be computed using the explained concept.
API 579-1 / ASME FFS-1 Power Industry Examples
Authors: Frey Joe , Carter Peter
Published: January 2011

The use of the fitness-for-service (FFS) standard API 579-1/ASME FFS-1 is increasing in the power industry. A fitness-for-service evaluation in a power plant can be performed to determine whether a unit can run safely until the next planned outage. This evaluation can save a significant amount of money. Examples of the effective application of API 579-1/ASME FFS-1 in the power industry are provided in this paper.
Stress-Rupture Behavior of Alloys 230 and 617 for High Temperature Applications
Authors: Hasan Muhammad H. , Chatterjee S. , Roy A. K. , Pal Joydeep
Published: January 2011

Austenitic Alloys 230 and 617 have been identified to be the two most suitable structural materials for heat exchanger application within the purview of the next generation nuclear plant (NGNP) program. The NGNP program is aimed at developing electricity and hydrogen using heat from very-high-temperature-reactor (VHTR). A maximum operating temperature of 950 °C has been recommended to achieve the highest possible efficiency in both electricity and hydrogen generation. The identification of Alloys 617 and 230 as heat exchanger materials was based on their excellent resistance to high-temperature degradations including creep, stress-rupture, fatigue and tensile deformation. Extensive efforts have been made to evaluate the creep and stress-rupture behavior of both alloys at temperatures relevant to the NGNP application. This paper presents the results of stress-rupture testing involving these alloys as functions of applied stress and temperature. The time to rupture was gradually reduced with simultaneous increase in stress and temperature, leading to a gradual reduction in the Larson-Miller-Parameter (LMP) indicating enhanced rupture tendency.
Lower Bound Methods in Elastic-Plastic Shakedown Analysis
Authors: Reinhardt Wolf , Adibi-Asl Reza
Published: January 2011

Several methods were proposed in recent years that allow the efficient calculation of elastic and elastic-plastic shakedown limits. This paper establishes a uniform framework for such methods that are based on perfectly-plastic material behavour, and demonstrates the connection to Melan’s theorem of elastic shakedown. The paper discusses implications for simplified methods of establishing shakedown, such as those used in the ASME Code. The framework allows a clearer assessment of the limitations of such simplified approaches. Application examples are given.
Water Hammer and Column Separation Due to Accidental Simultaneous Closure of Control Valves in a Large Scale Two-Phase Flow Experimental Test Rig
Authors: Bergant Anton , van ’t Westende Jos M. C. , Koppel Tiit , Gale Janez , Hou Qingzhi , Pandula Zoltan , Tijsseling Arris S.
Published: January 2011

A large-scale pipeline test rig at Deltares, Delft, The Netherlands has been used for filling and emptying experiments. Tests have been conducted in a horizontal 250 mm diameter PVC pipe of 258 m length with control valves at the downstream and upstream ends. This paper investigates the accidental simultaneous closure of two automatic control valves during initial testing of the test rig. The simultaneous closure of both valves has induced upsurge and downsurge at the same time. Large water hammer and column separation have caused failure of pipe supports and leakage at pipe joints. The incident was caused by a fault in an electronic conversion box due to power failure. Afterwards the downstream end automatic valve has been modified to a manually operated valve to avoid the accidental simultaneous closure of the valves. The accidental transient event has been fully recorded with pressures, flow rates and water levels. The measurements of the accident are presented, analyzed and discussed in detail. Photographs show the damages to the system.
Hyper-Gravity and Multiple Reflections in Wave Propagation in the Aorta
Authors: Kroot J. M. B. , Giannopapa C. G.
Published: January 2011

Hypergravity and gravity changes encountered in e.g. airplanes, rollercoasters and spaceflight can result in headaches or loss of consciousness due to decreased cerebral blood flow. This paper describes the effect of hypergravity and gravity changes on the pressure in the aorta and the distension of its wall. The model presented consists of a pressure part caused by gravity and a part representing pressure waves propagating through the vessel. The total pressure is described by a one-dimensional formulation in the frequency domain. To accommodate for geometrical and material variations, the vessel is modeled as a series of sections in which multiple reflections can occur. Results are presented for constant and varying gravity in straight and tapered flexible vessels.
Macroscopic and microscopic electrical characterizations of high-k ZrO2 and ZrO2/Al2O3/ZrO2 metal-insulator-metal structures
Authors: Martin Dominik , Grube Matthias , Weinreich Wenke , Müller Johannes , Wilde Lutz , Erben Elke , Weber Walter M. , Heitmann Johannes , Schröder Uwe , Mikolajick Thomas , Riechert Henning
Published: January 2011

In order for sub-10 nm thin films of ZrO2 to have a dielectric constant larger than 30 they need to be crystalline. This is done by either depositing the layer at higher temperatures or by a postdeposition annealing step. Both methods induce high leakage currents in ZrO2 based dielectrics. In order to understand the leakage a thickness series of ultrathin ZrO2 and nanolaminate ZrO2/Al2O3/ZrO2 (ZAZ) films, deposited by atomic layer deposition, was investigated. After deposition these films were subjected to different rapid thermal annealing (RTA) processes. Grazing incidence x-ray diffraction and transmission electron microscopy yield that the crystallization of ZrO2 during deposition is dependent on film thickness and on the presence of an Al2O3 sublayer. Moreover, the incorporation of Al2O3 prevents crystallites from spanning across the entire film during RTA. C-V and I-V spectroscopies show that after a 650 °C RTA in N2 the capacitance equivalent oxide thickness of 10 nm ZAZ films is reduced to 1.0 nm while maintaining low leakage currents of 3.2×10−8 A/cm2 at 1 V. Conductive atomic force microscopy studies yield that currents are not associated with significant morphological features in amorphous layers. However, after crystallization, the currents at crystallite grain boundaries are increased in ZrO2 and ZAZ films.
Control of semiconductor quantum dot nanostructures: Variants of SixGe1−x/Si quantum dot molecules
Authors: Murphy Jessica K. , Hull Robert , Pyle Devin , Wang Hao , Gray Jennifer , Floro Jerrold
Published: January 2011

We examine variations in the basic structure of quantum dot molecules (fourfold quantum dot nanostructures forming around a central facetted pit) in the SixGe1−x/Si(100) system. Arrays of quantum dot molecules are seeded by Ga+ focused ion beam (FIB) prepatterning of the Si substrate prior to epitaxial Si buffer layer growth and GexSi1−x film deposition. Five main variants to the regular quantum dot molecule structure are observed. The populations of these variant structures depend on the initial FIB processing conditions; their frequencies generally increase with increasing prepatterned pit depth and with increasing incident ion energy. This work suggests both routes to improving uniformity of regular quantum dot molecule arrays as well as routes to enabling synthesis of a wider range of nanostructure geometries.
Translational Pausing Ensures Membrane Targeting and Cytoplasmic Splicing of
XBP1u
mRNA
Authors: Yanagitani Kota , Kimata Yukio , Kadokura Hiroshi , Kohno Kenji
Published: January 2011

A peptide-mediated translational pause facilitates the unconventional splicing of a messenger RNA on the endoplasmic reticulum.
Aberrant Overexpression of Satellite Repeats in Pancreatic and Other Epithelial Cancers
Authors: Ting David T. , Lipson Doron , Paul Suchismita , Brannigan Brian W. , Akhavanfard Sara , Coffman Erik J. , Contino Gianmarco , Deshpande Vikram , Iafrate A. John , Letovsky Stan , Rivera Miguel N. , Bardeesy Nabeel , Maheswaran Shyamala , Haber Daniel A.
Published: January 2011

Noncoding RNAs transcribed from DNA repeats in heterochromatin are expressed at surprisingly high levels in tumors.
Numerous IgG4-positive plasma cells are ubiquitous in diverse localised non-specific chronic inflammatory conditions and need to be distinguished from IgG4-related systemic disorders
Authors: Strehl Johanna D , Hartmann Arndt , Agaimy Abbas
Published: January 2011

Background

IgG4-related systemic fibrosclerosis is a recently defined disorder characterised by a diffuse or tumefactive inflammatory reaction rich in IgG4-positive plasma cells associated with sclerosis and obliterative phlebitis. Although characteristic histopathological features are essential for the diagnosis of these disorders, to date there exists no consensus regarding the cut-off values used to define a ‘significant IgG4-positive plasma cell count,’ and data regarding the distribution of IgG4-positive plasma cells under common (non-specific) inflammatory conditions are lacking.

Methods

The authors analysed 121 randomly selected histopathological specimens containing prominent lymphoplasmacytic infiltrates (11 obstructive sialadenitis, 27 inflammatory lesions of the oral cavity, 24 inflammatory gastrointestinal lesions, 15 rheumatoid synovitis, 15 non-specific synovitis, eight non-specific dermatitis and 21 primary carcinomas with a peritumoral inflammatory response). For comparison, seven cases of sclerosing sialadenitis (Küttner tumour) were examined.

Results

High counts of IgG4 plasma cells were found in sclerosing sialadenitis (mean 40/high-power field (hpf)), contrasting sharply with sialadenitis caused by sialolithiasis (mean 3/hpf). Greatly varied but generally high counts of IgG4-positive plasma cells were also seen in several of the other lesions, particularly in rheumatoid synovitis (mean 55/hpf), oral cavity lesions (mean 79/hpf) and carcinoma-associated inflammatory response (mean 24/hpf). The mean IgG4/IgG ratios for all lesions varied between 0 and 0.4.

Conclusions

The results demonstrate the ubiquitous occurrence of variably high numbers of IgG4-positive plasma cells under diverse non-specific inflammatory conditions, indicating that high IgG4-positive plasma cell counts and high IgG4/IgG ratios per se do not reliably distinguish IgG4-associated systemic disease from non-specific conditions, and that the IgG4 counts must be cautiously interpreted in the context of appropriate clinical and histopathological features.
John Hughlings Jackson and our understanding of the epilepsies 100 years on
Authors: Iniesta Ivan
Published: January 2011

The term Jacksonian epilepsy was coined by Jean Martin Charcot following John Hughlings Jackson's 1870 paper ‘A study of convulsions’, where he had defined a convulsion as “a symptom resulting from an occasional, an excessive and a disorderly discharge of nerve tissue on muscles”. His earlier writings had included cases of syphilis related epilepsy, and the introduction of the first successful antiepileptic drugs—the bromides. Based on careful clinical observation or, as Hughlings Jackson himself put it, on the “experiments performed by disease”, ‘A study of convulsions’ was a synthesis of those previous reports which has contributed to our practical understanding of epilepsy, a contribution which continues to inform our thinking to the present day.
DNA attenuates enterocyte Toll-like receptor 4-mediated intestinal mucosal injury after remote trauma
Authors: Sodhi Chhinder , Levy Ryan , Gill Roop , Neal Matthew D. , Richardson Ward , Branca Maria , Russo Anthony , Prindle Thomas , Billiar Timothy R. , Hackam David J.
Published: January 2011

Intestinal mucosal injury occurs after remote trauma although the mechanisms that sense remote injury and lead to intestinal epithelial disruption remain incompletely understood. We now hypothesize that Toll-like receptor 4 (TLR4) signaling on enterocytes after remote injury, potentially through the endogenous TLR4 ligand high-mobility group box-1 (HMGB1), could lead to intestinal dysfunction and bacterial translocation and that activation of TLR9 with DNA could reverse these effects. In support of this hypothesis, exposure of TLR4-expressing mice to bilateral femur fracture and systemic hypotension resulted in increased TLR4 expression and signaling and disruption of the ileal mucosa, leading to bacterial translocation, which was not observed in TLR4-mutant mice. TLR4 signaling in enterocytes, not immune cells, was required for this effect, as adenoviral-mediated inhibition of TLR4 in enterocytes prevented these findings. In seeking to identify the endogenous TLR4 ligands involved, the expression of HMGB1 was increased in the intestinal mucosa after injury in wild-type, but not TLR4-mutant, mice, and administration of anti-HMGB1 antibodies reduced both intestinal mucosal TLR4 signaling and bacterial translocation after remote trauma. Strikingly, mucosal injury was significantly increased in TLR9-mutant mice, whereas administration of exogenous DNA reduced the extent of TLR4-mediated enterocyte apoptosis, restored mucosal healing, and maintained the histological integrity of the intestinal barrier after remote injury. Taken together, these findings identify a novel link between remote injury and enterocyte TLR4 signaling leading to barrier injury, potentially through HMGB1 as a ligand, and demonstrate the reversal of these adverse effects through activation of TLR9.
Cytoprotective effects of albumin, nitrosated or reduced, in cultured rat pulmonary vascular cells
Authors: Li Hui-Hua , Xu Jing , Wasserloos Karla J. , Li Jin , Tyurina Yulia Y. , Kagan Valerian E. , Wang Xiaorong , Chen Alex F. , Liu Zhao-Qian , Stoyanovsky Detcho , Pitt Bruce R. , Zhang Li-Ming
Published: January 2011

S-nitrosoalbumin (SNO-Alb) has been shown to be an efficacious cytoprotective molecule in acute lung injury, as well as ischemia-reperfusion injury in heart and skeletal muscle. Nonetheless, limited information is available on the cellular mechanism of such protection. Accordingly, we investigated the protective effects of SNO-Alb [ and its denitrosated congener, reduced albumin (SH-Alb) ] on tert-butyl hydroperoxide (tBH)-mediated cytotoxicity in cultured rat pulmonary microvascular endothelial cells (RPMEC), as well as hydrogen sulfide (H2S)-mediated cytotoxicity in rat pulmonary artery smooth muscle cells (RPASMC). We noted that tBH caused a concentration-dependent necrosis in RPMEC, and pretreatment of RPMEC with SNO-Alb dose-dependently decreased the sensitivity of these cells to tBH. A component of SNO-Alb cytoprotection was sensitive to NG-nitro-l-arginine methyl ester and was associated with activation of endothelial nitric oxide synthase (eNOS), phenomena that could be reproduced with pretreatment with SH-Alb. Exogenous H2S caused concentration-dependent apoptosis in RPASMC due to activation of ERK1/2 and p38, as well as downregulation of Bcl-2. Pretreatment with SNO-Alb reduced H2S-mediated apoptosis in a concentration-dependent manner that was associated with SNO-Alb-mediated inhibition of activation of ERK1/2 and p38. Pretreatment with SNO-Alb reduced toxicity of 1 mM sodium hydrosulfide in an NG-nitro-l-arginine methyl ester-sensitive fashion in RPASMC that expressed gp60 and neuronal NOS and was capable of transporting fluorescently labeled SH-Alb. Therefore, SNO-Alb is cytoprotective against models of oxidant-induced necrosis (tBH) and inhibitors of cellular respiration and apoptosis (H2S) in both pulmonary endothelium and smooth muscle, respectively, and a component of such protection can be attributed to a SH-Alb-mediated activation of constitutive NOS.
CCT241533 Is a Potent and Selective Inhibitor of CHK2 that Potentiates the Cytotoxicity of PARP Inhibitors
Authors: Anderson Victoria E. , Walton Michael I. , Eve Paul D. , Boxall Katherine J. , Antoni Laurent , Caldwell John J. , Aherne Wynne , Pearl Laurence H. , Oliver Antony W. , Collins Ian , Garrett Michelle D.
Published: January 2011

CHK2 is a checkpoint kinase involved in the ATM-mediated response to double-strand DNA breaks. Its potential as a drug target is still unclear, but inhibitors of CHK2 may increase the efficacy of genotoxic cancer therapies in a p53 mutant background by eliminating one of the checkpoints or DNA repair pathways contributing to cellular resistance. We report here the identification and characterization of a novel CHK2 kinase inhibitor, CCT241533. X-ray crystallography confirmed that CCT241533 bound to CHK2 in the ATP pocket. This compound inhibits CHK2 with an IC50 of 3 nmol/L and shows minimal cross-reactivity against a panel of kinases at 1 μmol/L. CCT241533 blocked CHK2 activity in human tumor cell lines in response to DNA damage, as shown by inhibition of CHK2 autophosphorylation at S516, band shift mobility changes, and HDMX degradation. CCT241533 did not potentiate the cytotoxicity of a selection of genotoxic agents in several cell lines. However, this compound significantly potentiates the cytotoxicity of two structurally distinct PARP inhibitors. Clear induction of the pS516 CHK2 signal was seen with a PARP inhibitor alone, and this activation was abolished by CCT241533, implying that the potentiation of PARP inhibitor cell killing by CCT241533 was due to inhibition of CHK2. Consequently, our findings imply that CHK2 inhibitors may exert therapeutic activity in combination with PARP inhibitors. Cancer Res; 71(2); 463–72. ©2011 AACR.
Use of Macrophages to Target Therapeutic Adenovirus to Human Prostate Tumors
Authors: Muthana Munitta , Giannoudis Athina , Scott Simon D. , Fang Hsin-Yu , Coffelt Seth B. , Morrow Fiona J. , Murdoch Craig , Burton Julian , Cross Neil , Burke Bernard , Mistry Roshna , Hamdy Freddie , Brown Nicola J. , Georgopoulos Lindsay , Hoskin Peter , Essand Magnus , Lewis Claire E. , Maitland Norman J.
Published: January 2011

New therapies are required to target hypoxic areas of tumors as these sites are highly resistant to conventional cancer therapies. Monocytes continuously extravasate from the bloodstream into tumors where they differentiate into macrophages and accumulate in hypoxic areas, thereby opening up the possibility of using these cells as vehicles to deliver gene therapy to these otherwise inaccessible sites. We describe a new cell-based method that selectively targets an oncolytic adenovirus to hypoxic areas of prostate tumors. In this approach, macrophages were cotransduced with a hypoxia-regulated E1A/B construct and an E1A-dependent oncolytic adenovirus, whose proliferation is restricted to prostate tumor cells using prostate-specific promoter elements from the TARP, PSA, and PMSA genes. When such cotransduced cells reach an area of extreme hypoxia, the E1A/B proteins are expressed, thereby activating replication of the adenovirus. The virus is subsequently released by the host macrophage and infects neighboring tumor cells. Following systemic injection into mice bearing subcutaneous or orthotopic prostate tumors, cotransduced macrophages migrated into hypoxic tumor areas, upregulated E1A protein, and released multiple copies of adenovirus. The virus then infected neighboring cells but only proliferated and was cytotoxic in prostate tumor cells, resulting in the marked inhibition of tumor growth and reduction of pulmonary metastases. This novel delivery system employs 3 levels of tumor specificity: the natural “homing” of macrophages to hypoxic tumor areas, hypoxia-induced proliferation of the therapeutic adenovirus in host macrophages, and targeted replication of oncolytic virus in prostate tumor cells. Cancer Res; 71(5); 1805–15. ©2011 AACR.