bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Hot Spot and Corrosion Damage in Conical Pressure Components
Authors: Adibi-Asl R. , Seshadri R.
Published: January 2011

Structural integrity of an in-service component containing damage such as corrosion and thermal hot spot has to be evaluated regularly so as to certify the acceptance and safety of continued service of the component. In this paper, limit load solutions of a damaged conical shell, particularly local wall thinning and thermal hot spot, is investigated. The derived solutions are based on identifying the regions in the damaged component that directly participate in the plastic action (kinematically active). The concepts of reference volume and decay length are employed to identify the kinematically active regions in the damaged conical shell. The different solutions proposed in this paper are compared with elastic-plastic finite element analysis. The results indicate that proposed solutions can be used with acceptable accuracy to make integrity assessment decisions.
A Method for Detecting the Cold Welding and Optimizing the Welding Procedure for the Electro-Fusion Joints in PE Pipes
Authors: Xu Ping , Guo Weican , Ding Shoubao , Zuo Shangzhi , Shi Ping
Published: January 2011

Electro-fusion (EF) joints are widely used in polyethylene (PE) pipes connection. In the paper, a method for assessing the cold welding and optimizing the welding technology for such joints is developed. An Eigen-line in the EF joint is observed by using the phased array ultrasonic focusing technique as well as B-scan real image technology. A method called “Eigen-line method” is developed to assess cold welding with an empirical formula by measuring the distance between the line and metal wires. A lot of tests show that the developed method can be used to assess the welding technology by measuring the moving speed of the Eigen-line and the distance between the line and metal wires in UT real-time video. Based on UT real-time video experiments, the optimized welding prcedure for joints is obtained, which greatly reduce the time and cost in development of EF joints in PE pipes.
Thermal Aging and Neutron Embrittlement Evaluation of Cast Austenitic Stainless Steels
Authors: Mehta Hardayal S. , Frew Brian D. , Horn Ronald M. , Hua Fred , Ranganath Sampath , Carter Robert G.
Published: January 2011

NUREG-1801, Rev. 1, Section XI.M.13, states that an ASME Code Section XI VT-3 examination is required to be performed of reactor internal components. In addition, the NUREG report specifies that for the license renewal period, these inspections shall be augmented by an aging management program to assess the synergistic effects of thermal aging and neutron embittlement of cast austenitic stainless steel (CASS) components. This aging management program consists of (a) identifying susceptible components; and (b) either performing additional inspections of these components, or performing a component-specific evaluation to confirm that the stresses in the components are sufficiently low such that augmented inspections are not warranted. This paper presents the results of evaluations conducted to assess the potential synergistic effects of thermal aging and neutron embrittlement of CASS components in BWR internals and recommend augmented inspections if needed. The evaluation shows that all the BWR CASS components have ferrite levels below the level for which aging embrittlement is a concern. Furthermore, for the Control Rod Guide Tube Base and Core Spray Sparger Nozzle Elbows, the end of life fluence is less than the threshold value for toughness loss. The end-of-life fluence levels for the orificed fuel support, the jet pump assembly castings and the Low Pressure Core Injecion (LPCI) Couplings exceed the threshold, but the toughness data for irradiated austenitic stainless steel show that these components will have sufficient fracture toughness at end of the license renewal period so that augmented inspection is not required. It is concluded that augmented inspections are not required for the BWR CASS internals.
Welding Induced Distortions and Strains of a Built-Up Panel: Experiment and Numerical Validation
Authors: Bayley Christopher , Goldak John
Published: January 2011

Weld build-up or weld cladding is a welding process in which weld metal can be deposited in order to reclaim the material thickness. In certain applications, welding induced distortions must be controlled while simultaneously minimizing welding induced residual strains. In order to examine the relative effect of the weld build-up region on welding induced distortion and residual strains, two panels were fabricated with either a small 100 × 100 × 3 or large 200 × 200 × 3 mm depression that was subsequently filled by welding. During welding, the strains, displacements and temperature were continuously monitored in order to compare the transient solution with companion FEM models of the same structures. The coupled thermo-mechanical problem was solved using Goldak Technology Inc.s VrSuite program, with the level of agreement of the measured distortions, strains and temperature profiles dependent on their location and history. Both the numerical and experimental tests showed that despite the differences in the geometry, both panels developed the same strain state, although the large welded patch had greater peak value and larger distortions.
Fracture Behavior of Friction Stir Spot Welded Joint
Authors: Mourad Abdel-Hamid I. , Harib Khalifa H. , El-Domiaty Aly
Published: January 2011

The fracture behaviour of lap-shear joints manufactured by friction stir spot welding (FSSW) technique is examined in this paper. Two aluminium sheets of 2.8 mm thickness were welded using different process parameters to form a lap-shear joint. Special tool was designed and fabricated for the stir-spot welding process. Tensile-shear tests were performed to determine the tensile-shear load bearing capacity and toughness of the weld. The stress intensity factor and the J-integral around a weld are determined in order to characterize the fracture behavior. The effect of different main process controlling parameters, e.g., the tool prop pin rotating speed, duration action time and sinking/penetration depth into the lower welded sheet on the weld fracture behaviour has been investigated through an intensive experimental program. Optical and scanning electron microscopes fractographes were obtained to examine the weld fracture modes. The results show that higher frictional heat due to relatively higher tool probe pin rotational speed and penetration depth into the lower sheet produces improved joint static strength and toughness.
Diagnostics of Nuclear Power Plant Components Due to Thickness Measurement by Using Digital Radiography
Authors: Mochizuki Masahito , Kanno Satoshi , Shimizu Shunichi , Daitou Yuichi
Published: January 2011

Technical Guide for Diagnostics of Power Plant Components Technique due to Thickness Measurement by Digital Radiography, JEAG 4224–2009, was issued from Nuclear Standard Committee of Japan Electric Association on June 2009. Two types of digital radiography are applied to thickness measurement; imaging plate (IP) and color image intensifier (Color I. I. ). Organization and detailed contents of the technical guide is introduced in this paper.
Creep Strength Evaluation of Welded Joint Made of Modified 9Cr-1Mo Steel for Japanese Sodium Cooled Fast Reactor (JSFR)
Authors: Wakai Takashi , Nagae Yuji , Onizawa Takashi , Obara Satoshi , Xu Yang , Ohtani Tomomi , Date Shingo , Asayama Tai
Published: January 2011

This paper describes a proposal of provisional allowable stress for the welded joints made of modified 9Cr-1Mo steel (ASME Gr.91) applicable to the structural design of Japanese Sodium cooled Fast Reactor (JSFR). For the early commercialization of the SFRs, economic competitiveness is one of the most essential requirements. One of the most practical means to reduce the construction costs is to diminish the total amount of structural materials. To meet the requirements, modified 9Cr-1Mo steel has attractive characteristics as a main structural material of SFRs, because the steel has both excellent thermal properties and high temperature strength. Employing the steel to the main pipe material, remarkable compact plant design can be achieved. There is only one elbow in the hot leg pipe of the primary circuit. However, in such a compact piping, it is difficult to keep enough distance between welded joint and high stress portion. In the welded joints of creep strength enhanced ferritic steels including ASME Gr.91 (modified 9Cr-1Mo) steel, creep strength may obviously degrade especially in long-term region. This phenomenon is known as “Type-IV” damage. Though obvious strength degradation has not observed at 550°C yet for the welded joint made of modified 9Cr-1Mo steel, it is proper to suppose strength degradation must take place in very long-term creep. Therefore, taking strength degradation due to “Type-IV” damage into account, the allowable stress applicable to JSFR pipe design was proposed based on creep rupture test data acquired in temperature accelerated conditions. Available creep rupture test data of welded joints made of modified 9Cr-1Mo steel provided by Japanese steel vender were collected. The database was analyzed by region partition method. The creep rupture data were divided into two regions of short-term and long-term and those were individually evaluated by regression analyses with Larson Miller Parameter (LMP). Boundary condition between short-term and long-term was half of 0.2% proof stress of base metal at corresponding temperature. First order equation of logarithm stress was applied. For conservativeness, allowable stress was proposed provisionally considering design factor for each region. Present design of JSFR hot leg pipe of primary circuit was evaluated using the proposed allowable stress. As a result, it was successfully demonstrated that the compact pipe design was assured. For validation of the provisional allowable stress, a series of long-term creep tests were started. In future, the provisional allowable stress will be properly reexamined when longer creep rupture data are obtained. In addition, some techniques to improve the performance of welded joints were surveyed and introduced.
Multiaxial Fatigue Failure Criterion Considering Formation and Growth of Small Cracks
Authors: Takahashi Yukio
Published: January 2011

Treatment of stress multiaxiality in fatigue assessment is practically important in many components subjected to cyclic loading during their operation. Based on the results of fatigue tests on hollow and solid bar specimens of SUS316NG and SGV410 under various combinations of axial and torsional stresses, accuracy of fatigue life prediction based on the conventional parameters as well as a two parameter approach newly proposed here was studied. The conventional parameters tended to provide conservative prediction of the failure life for shear-dominated cases especially for SUS316NG while the new approach was able to give more realistic prediction of failure lives.
Development of a Web-Based LNG Plant Management System for Reliability Assessment Covering From Design Stage to Maintenance
Authors: Kim Yu-Gyeong , Kim Joo-Dong , Choi Jae-Boong
Published: January 2011

In recent years, the three-dimensional virtual plant is introduced in the development of plant management system for visually enhanced plant management. A VR (Virtual Reality) based integrity assessment system has been proposed for the nuclear power plant. Consequently, a web-based monitoring system has been developed on the basis of virtual plant by combining graphic visibility with safety margin calculations. However, previous researches were mostly focused on the safety maintenance of nuclear power plants, and did not consider the design stage. This paper proposes a system for the LNG (Liquefied Natural Gas) plant management covering from design stage via construction to the maintenance stage. The management system proposed in this paper includes a virtual plant to enable design review in the design stage, the EDB (Engineering DataBase) which manages the engineering data produced in the design stage and a web based aging monitoring system which can be used in the maintenance stage. The proposed system runs on the Internet on the basis of 3-D graphics system and it is expected to be used for more efficient and reliable LNG plant management.
Modification of Leak Before Break Criterion With Focus on the Residual Stress
Authors: Macurova Katerina , Tichy Richard , Strnadel Bohumir
Published: January 2011

The article deals with the study of the conditions of breach of pressure vessels and determination of the safety of use of the modified criteria of Leak Before Break when a residual stress is found in the material of a vessel. Design criterion is based on a critical crack length, which must be less than the thickness of the vessel wall. In this case it is guaranteed that there will not be an uncontrolled breach of the vessel. Superposition of residual stress, which occurs in the production of a vessel by impact extrusion, and the hoop stress caused by the internal pressure significantly affects the life and conditions of technical use. Size and character of the distribution of residual stresses were determined experimentally by use of the hole-drilling method. The numerical simulation and mathematical calculations used ANSYS and MATLAB software. The main attention was focused on the application of residual stress in the numerical analysis, based on values obtained by the experimental measurements hole–drilling method.
Determination of CANDU End Fitting Jacking Limits Using Elastic-Plastic Finite Element Analysis
Authors: Li Bing , McNeish Dave , Eom Seyun , Vijay D. K. , Lin Si-tsai , Li Jian
Published: January 2011

In one CANDU reactor unit in Ontario, the west end fitting is designed to connect to the end shield via a stop collar. The outboard end of the stop collar is welded to an attachment ring which shrink-fits on the end fitting body. The east side end fitting is supported by inboard and outboard journal rings resting on their respective bearing sleeves which allow the ‘free’ axial movement of the channel. In support of some maintenance activities, the west end fitting is required to be jacked to get certain clearance for accommodating the operating tools. The previous elastic calculation got the jacking limit of 0.35″ while did not provide enough clearance for tooling. In this paper, an elastic-plastic finite element analysis following ASME B&PV code Section III, Division 1, Subsection NB is performed to increase the jacking limit. The finite element analysis is carried out using ANSYS and validated by an ABAQUS model. In the elastic-plastic finite element analysis, the following effects are considered: strain hardening of stop collar material, stress concentration in stop collar weld, notch effect on stress concentration and fatigue in stop collar. Cyclic jacking loads as displacement controlled loading are applied in the analysis. Considering the time to the end of unit life, the maximum anticipated end fitting jacking cycles are 8. The higher jacking limit is achieved with an acceptable plastic deformation and fatigue damage at the stop collar, which is the weakest part during the end fitting jacking. The results show that the end fitting can be jacked at west side End-face with 1.17″ for 1–3 cycles, 1.15″ for 4 cycles, 1.03″ for 5 cycles, 0.95″ for 6 cycles, 0.85″ for 7 cycles and 0.80″ for 8 cycles. The jacking limits achieved in this paper provide enough clearance for the required maintenance operations.
Material Behavior of Two High Grade Pipe Steels Under Different Triaxility Levels
Authors: Cravero S. , Bravo R. , Mantovano L. , Ernst H.
Published: January 2011

Particular geometries and loading conditions may have important effects on the stress fields of a given component promoting complex triaxial stress states and modifying the hydrostatic stress level. The yield condition of a ductile material is represented by the von Mises stress. However, the triaxial stress states have important effects on material toughness and ductility. This work presents a study of the effects of stress concentrators (different triaxial stress states) on material rupture. The aim is to determine the effects of hydrostatic stresses on the strain at failure in two low alloy high strength mill steels employed in field well and linepipe applications. Cylindrical specimens with different notch radius were tested to obtain different hydrostatic to von Mises stress ratios during tensile tests (h = σh/σVM). The considered notch radii were 2.0, 0.8, 0.4 and 0.25 mm. The notched specimens were loaded in tension and applied load vs. reduction of transversal area data were recorded during the tests. Numerical simulations of the tensile tests allow reproducing the test in the numerical model and calculating the stress and strains fields during each stage of the applied loading. Finally, tables of strain at failure vs. stress triaxiality are obtained for both steels that allow determining the most appropriate material for critical applications.
Comparison of Elastic-Plastic Analysis and Experimental Result for Locally Thinned Pipe
Authors: Reinhardt Wolf , Duan Xinjian
Published: January 2011

The result of a burst test of a thinned straight pipe with local thinning is reported. The locally thinned region had a thickness well below the NB-3600 pressure based Design thickness. The burst pressure is compared with the maximum Design pressure obtained from a variety of elastic-plastic analysis methods, such as plastic limit analysis and the Section VIII Div. 2 elastic-plastic design method.
Design of a Weld Overlay for a Large Bore Pipe Nozzle to Optimize Residual Stress
Authors: Killian Douglas E.
Published: January 2011

Full Structural Weld Overlays (FSWOL) have been used successfully in the nuclear power industry for a number of years to mitigate and repair small (4″) to medium (10″) bore welded piping components susceptible to primary water stress corrosion cracking (PWSCC). Mitigation is provided by the creation of compressive residual stress on the inside surface of the pipe as layers of weld overlay are deposited over the outside surface of the pipe. ASME Code Case N-740-2 requires that these overlay designs provide adequate structural integrity considering the growth of postulated 75% through-wall inside surface flaws by PWSCC and cyclic fatigue. Application of this repair procedure to larger diameters components such as 30 inch reactor vessel nozzles is not practical due to the large amount of weld metal (overlay thickness) which would be required to satisfy the design requirements of a FSWOL and the associated demands on implementation schedule and exposure to radiation. An alternate procedure is currently being considered for these larger components which utilizes an Optimized Weld Overlay (OWOL) design based on a reduced thickness and smaller postulated flaw. In particular, ASME Code Case 754 specifies, in part, that 50% through-wall inside surface flaws be shown to be acceptable. Furthermore, an OWOL would continue to provide mitigation of materials susceptible to PWSCC by requiring that the thickness of the overlay be sufficient to induce compressive residual stress on the inside surface. This paper presents results of finite element analysis for an optimized weld overlay on a large bore (30″) reactor vessel coolant nozzle dissimilar metal weld, with particular attention to the incremental development of residual stress with each layer of weld metal. Through numerical simulation of the complete fabrication history, including repair of the original dissimilar metal weld, hydrostatic testing, and completion of the nozzle safe end-to-pipe joint prior to implementation of the overlay, the pre-overlay state of stress is defined for use as the basis for evaluating the stress improvement provisions of the weld overlay process. Results are obtained for both kinematic and isotropic hardening rules to study the effect of these two extreme measures of material characterization on the development of residual stress. Additional results are presented to study the sensitivity of the welding simulations to material yield strength and mesh refinement. Predicted stresses are also compared to measured data from a full scale mockup of a large bore reactor vessel nozzle with an optimized weld overlay.
Experimental Validation of Inverse Techniques for the Remote Identification of Impact Forces in Gap-Supported Systems Subjected to Local and Flow Turbulence Excitations
Authors: Delaune Xavier , Piteau Philippe , Debut Vincent , Antunes Jose
Published: January 2011

Predictive computations of the nonlinear dynamical responses of gap-supported tubes subjected to flow excitation have been the subject of active research. Nevertheless, experimental results are still necessary, for validation of the theoretical predictions as well as for asserting the integrity of field components. Because carefully instrumented test tubes and tube-supports are seldom possible, due to space limitations and to the severe environment conditions, there is a need for robust techniques capable of extracting relevant information from the actual vibratory response data. Although at the present time such analysis is over-ambitious, as far as the multi-supported tube bundles of real-life components are concerned, the same instrumentation difficulties frequently apply in the case of laboratory test rigs. Therefore, the subject of this paper is of practical significance even in the more modest realm of laboratory experiments. The knowledge of the dynamical contact/impact (vibro-impact) forces is of paramount significance, as also the tube/support gaps. Following our previous studies in this area using wave-propagation techniques [1–3], we recently applied modal methods for extracting such information. Based on numerically simulated time-domain vibro-impact responses, the dynamical support forces, as well as the vibratory responses at the support locations, were identified from one or several vibratory responses at remote locations, from which the support gaps could also be inferred [4]. Also recently, for the related problem of friction force identification on bowed strings, preliminary experiments have shown the feasibility of these identification techniques [5]. In the present paper, the modal identification techniques developed in [4,5] are tested using an experimental rig built at CEA/Saclay, consisting on a randomly excited clamped-free beam which impacts on an intermediate gap-support. Identification of the impact force, as well as of the beam motion at the gap-support, are achieved based on remote measurements of the beam response provided by two accelerometers. A significant feature of the experimental identifications presented in this paper is that, beyond the results obtained under a point-force shaker excitation, we test here an original technique to identify the gap-supported reactions in flow-excited systems, which was recently introduced in [4]. As for most inverse problems, the identification results may prove sensitive to both noise and modeling errors. Therefore, regularization techniques discussed in [4] are used to mitigate the effects of unmeasured noise perturbations. Overall, the experimentally identified results compare reasonably well with the measured contact forces and motions at the gap-supports. Actually, even if our identifications are not immaculate at the present time, they remain nevertheless quite usable.
Influencing Factors for Improving Accuracy in Prediction of Stress Corrosion Crack Growth Rate in Boiling Water Reactor Operational Condition: Part 1—Prediction of SCC Growth Rate in Terms of Vickers Hardness
Authors: Takeda Yoichi , Lu Zhanpeng , Adachi Takeshi , Peng Qunjia , Kuniya Jiro , Shoji Tetsuo
Published: January 2011

It is known that stress corrosion cracking (SCC) found in the operational power plants show complex cracking behaviors and it’s resulted in complex crack shape e.g. crack branching and its uneven crack front. For the cracking near the weldment, this is due to crack penetrated along the complex distribution of residual stress and strain hardened area. In this investigation, in order to advance the accuracy for crack growth prediction with considering such complex fields, theoretical formulation for SCC growth was further modified. Hardness of the materials, which is a measureable parameter even in operational power plant, was focused on to reflect strain hardening of the component like heat affected zone of the weldments. The theoretical formulation for SCC growth has terms with yield strength of the material and strain hardening exponent to describe crack tip strain rate. Strain hardening was simulated by cross rolling with the range of 4 – 32% as thickness reduction. Correlation between yield strength, strain hardening exponent at 288°C and Vickers hardness was obtained by means of tensile tests and hardness tests on 316L stainless steel. It was observed that a monotonic increase in Vickers hardness and yield strength with degree of reduction in thickness worked by cross rolling. Relationship between Vickers hardness and yield strength was found to have linear correlation. Further confirmation was made by plotting the reported mechanical properties data in terms of Vickers hardness. In addition, linear relationship was found between yield strength and strain hardening exponent. These relationships were introduced into SCC theoretical formulation and a SCC growth rate prediction curve in terms of Vickers hardness was proposed. SCC crack growth evaluation tests with selected work hardened 316L stainless steel were performed in oxygenated pure water environment at 288°C to confirm the predictability of the formulation. The prediction curve had a good agreement with available literature data as well as obtained crack growth rates in the hardness range of 140–300HV which was likely expected one in weld HAZ.
Contributory Factors to Accurate Prediction of Rate of Stress Corrosion Cracking in Boiling Water Reactor Under Unexpected Condition During Operation: Part 3—The Effect of High Loading Rate on SCC Growth Behaviour
Authors: Tanabe Yuji , Tamura Takeo , Suzuki Kenji , Kuniya Jiro , Shoji Tetsuo
Published: January 2011

The goal of the study is to reveal the effect of high loading rate on the stable SCC growth behaviour of nuclear-grade stainless steel, SUS316L. To this end, the Split-Hopkinson pressure bar (SHPB) experiments on SUS316L were performed first to establish the dynamic tensile stress-strain response at strain rates up to 700s−1. The analyses of dynamic stress intensity factors for wedge loading experiments on modified compact tension specimens during SCC test were then performed by the finite element method. The outline of the wedge loading experiments by the use of the Split-Hopkinson pressure bar is briefly mentioned in this paper as well.
Composite Material Property Database Using Smooth Specimens to Generate Design Allowables With Uncertainty Estimation
Authors: Shah Pranav D. , Melo Jose Daniel D. , Cimini Carlos A. , Fong Jeffrey T.
Published: January 2011

For brevity, the class of “composite materials” in this paper is intended to refer to one of its subclasses, namely, the fiber-reinforced composite materials. In developing composite material property databases, three categories of data are needed. Category 1 consists of all raw test data with detailed information on specimen preparation, test machine description, specimen size and number per test, test loading history including temperature and humidity, etc., test configuration such as strain gage type and location, grip description, etc. Category 2 is the design allowable derived from information contained in Category 1 without making further experimental tests. Category 3 is the same design allowable for applications such that new experiments prescribed by user to obtain more reliable properties for the purpose on hand. At present, most handbook-based composite material property databases contain incomplete information in Category 1 (raw data), where a user is given only the test average values of properties such as longitudinal, transverse, and shear moduli, major and out-of-plane Poisson’s ratios, longitudinal tensile and compressive, transverse tensile and compressive, and shear strengths, inter-laminar shear strength, ply thickness, hygrothermal expansion coefficients, specific gravity, fiber volume fraction, etc. The presentation in Category 1 ignores the inclusion of the entire test environment description necessary for a user to assess the uncertainty of the raw data. Furthermore, the design allowable listed in Category 2 is deterministically obtained from Category 1 and the user is given average design allowable without uncertainty estimation. In this paper, it is presented a case study where average design allowable failure envelopes of open hole specimens were obtained numerically for two different quasi-isotropic carbon fiber-epoxy laminates using the appropriate Category 1 data. Using the method of statistical design of experiments, it is then showed how the average design allowable can be supplemented with uncertainty estimates if the Category 1 database is complete. Application of this methodology to predicting reliability of composite structures is discussed.
Etch mechanisms of silicon gate structures patterned in SF6/CH2F2/Ar inductively coupled plasmas
Authors: Luere O. , Pargon E. , Vallier L. , Pelissier B. , Joubert O.
Published: January 2011

Patterning complex metal gate stack becomes increasingly challenging since the gate dimension for all isolated as well as dense gate structures present on 300 mm wafer needs to be controlled within the nanometer range. In this article, the authors show that SF6/CH2F2/Ar plasma chemistries to etch the polysilicon gate present very interesting critical dimension (CD) control capabilities for advanced gate etch strategies compared to commonly used HBr/O2/Cl2 plasma chemistries, thanks to the different mechanisms involved in the passivation layer formation on the gate sidewalls. Indeed, contrary to HBr/Cl2/O2 plasma chemistries, the passivation layers in SF6/Ar/CH2F2 plasmas are not formed from deposition of etch by-products coming from the gas phase but the passivating species are chemically sputtered from the bottom of the etched structures and coat the silicon sidewalls by line of sight deposition. Such mechanisms result in thin and uniform CFX passivation layers on the gate sidewalls very similar in dense and isolated structures leading to an improved CD control.
Inhibition of carbon growth and removal of carbon deposits on extreme ultraviolet lithography mirrors by extreme ultraviolet irradiation in the presence of water, oxygen, or oxygen/ozone mixtures
Authors: Niibe Masahito , Koida Keigo , Kakutani Yukinobu
Published: January 2011

Experiments involving the inhibition of carbon growth and removal of carbon deposits on extreme ultraviolet (EUV) lithography mirrors were carried out. First, a carbon film was deposited on a Ru-capped Mo/Si multilayer mirror by introducing n-decane gas at a pressure of 1.3×10−5 Pa into the vacuum chamber and irradiating this mirror with an EUV dose of 380 J/mm2. Following, the mirror was further exposed to EUV irradiation while introducing water vapor, oxygen, or oxygen/ozone mixtures at a gas pressure of 1.0×10−2 Pa into the chamber. The reflectivity of the mirror, which was decreased upon carbon-film growth, could be recovered by the introduction of oxygen or oxygen/ozone mixtures. In the inhibition experiment, EUV irradiation was carried out while introducing n-decane gas at a pressure of 1.3×10−5 Pa and, simultaneously, water vapor, oxygen, or oxygen/ozone mixtures with a pressure of about 1×10−2 Pa. No remarkable inhibition of carbon-film growth was observed for water vapor and oxygen gas. However, a definite inhibition was observed with the introduction of oxygen/ozone mixtures.
Electrical characteristics of Ti–Ta–O based MIM capacitors
Authors: Lukosius M. , Kaynak C. Baristiran , Wenger Ch. , Ruhl G. , Rushworth S.
Published: January 2011

Amorphous Ti–Ta–O thin films were deposited by the atomic-vapor deposition technique for metal-insulator-metal (MIM) applications. Depositions were carried out at 400 °C on 200-mm Si (100) wafers using TiN and TaN as bottom electrode materials. The comparison of electrical properties of MIM capacitors was done after physical-vapor deposited growth of different top electrodes, namely, Au, TiN, TaN, and Ti. Capacitance-voltage measurements revealed that the dielectric constant of 50 can be reached if Ti–Ta–O layers are deposited on TiN and if Au, TaN, or Ti is used as the top electrode. The k value is reduced to 37 if TaN is used as bottom electrode. However, if TiN is used as the top electrode, the k value of the stack is reduced by a factor of 3, from 50 to 17, independent of whether TiN or TaN are used as bottom electrodes. The lowest leakage current values (∼10−8 A/cm2) were observed when gold was used as the top electrode, whereas it increased by 3 orders of magnitude if the top electrode was changed to TiN and even more if the top electrode was changed to TaN or Ti.
Proteome Half-Life Dynamics in Living Human Cells
Authors: Eden Eran , Geva-Zatorsky Naama , Issaeva Irina , Cohen Ariel , Dekel Erez , Danon Tamar , Cohen Lydia , Mayo Avi , Alon Uri
Published: January 2011

In times of stress, long-lived proteins increase their durability.
Transfusion-TransmittedBabesiaspp.: Bull's-Eye onBabesia microti
Authors: Leiby David A.
Published: January 2011

Babesiaspp. are intraerythrocytic protozoan parasites of animals and humans that cause babesiosis, a zoonotic disease transmitted primarily by tick vectors. Although a variety of species or types ofBabesiahave been described in the literature as causing infection in humans, the rodent parasiteBabesia microtihas emerged as the focal point of human disease, especially in the United States. Not only hasB. microtibecome established as a public health concern, this agent is increasingly being transmitted by blood transfusion: estimates suggest that between 70 and 100 cases of transfusion-transmittedBabesia(TTB) have occurred over the last 30 years. A recent upsurge in TTB cases attributable toB. microti, coupled with at least 12 fatalities in transfusion recipients diagnosed with babesiosis, has elevated TTB to a key policy issue in transfusion medicine. Despite clarity on a need to mitigate transmission risk, few options are currently available to prevent the transmission ofB. microtiby blood transfusion. Future mitigation efforts may stress serological screening of blood donors in regionalized areas of endemicity, with adjunct nucleic acid testing during the summer months, when acute infections are prevalent. However, several hurdles remain, including the absence of a licensed blood screening assay and a thorough cost-benefit analysis of proposed interventions. Despite current obstacles, continued discussion of TTB without proactive intervention is no longer a viable alternative.
Taxonomy, Epidemiology, and Clinical Relevance of the Genus
Arcobacter
Authors: Collado Luis , Figueras Maria José
Published: January 2011

The genus
Arcobacter
, defined almost 20 years ago from members of the genus
Campylobacter
, has become increasingly important because its members are being considered emergent enteropathogens and/or potential zoonotic agents. Over recent years information that is relevant for microbiologists, especially those working in the medical and veterinary fields and in the food safety sector, has accumulated. Recently, the genus has been enlarged with several new species. The complete genomes of
Arcobacter butzleri
and
Arcobacter nitrofigilis
are available, with the former revealing diverse pathways characteristic of free-living microbes and virulence genes homologous to those of
Campylobacter.
The first multilocus sequence typing analysis showed a great diversity of sequence types, with no association with specific hosts or geographical regions. Advances in detection and identification techniques, mostly based on molecular methods, have been made. These microbes have been associated with water outbreaks and with indicators of fecal pollution, with food products and water as the suspected routes of transmission. This review updates this knowledge and provides the most recent data on the taxonomy, species diversity, methods of detection, and identification of these microbes as well as on their virulence potential and implication in human and animal diseases.
Progress and Problems in Understanding and Managing Primary Epstein-Barr Virus Infections
Authors: Odumade Oludare A. , Hogquist Kristin A. , Balfour Henry H.
Published: January 2011

Epstein-Barr virus (EBV) is a gammaherpesvirus that infects a large fraction of the human population. Primary infection is often asymptomatic but results in lifelong infection, which is kept in check by the host immune system. In some cases, primary infection can result in infectious mononucleosis. Furthermore, when host-virus balance is not achieved, the virus can drive potentially lethal lymphoproliferation and lymphomagenesis. In this review, we describe the biology of EBV and the host immune response. We review the diagnosis of EBV infection and discuss the characteristics and pathogenesis of infectious mononucleosis. These topics are approached in the context of developing therapeutic and preventative strategies.
Comments on the dilemma in the November/December issue: ‘Tethered dog dies’
Authors: Marshall Freddie
Published: January 2011

The dilemma in the November/December issue concerned a vet who transported a dog between clinics in the boot of an estate car (In Practice, November/December 2010, volume 32, pages 514–515). The animal was secured with a lead, but on arrival it was found dead, trapped with the lead around its neck. The noises the dog had been making seemed to be agitation, and when they stopped the vet assumed the dog had gone to sleep. Pippa Swan commented that it could be assumed that the cause of death was strangulation and that the dog had suffered. It might have been a tragic misjudgement, but that could not absolve the vet's responsibility for the animal. A possible way forward would be to consider whether a vet who had behaved in this way should be judged more harshly than a member of the public. While vets should know the consequences of tying up a dog without proper supervision, they were also human and could make mistakes. Were the incident to be reported, the consequences for the vet might not stop at going to court; the RCVS Disciplinary Committee might decide that the vet was guilty of serious professional misconduct. If there was no evidence that the behaviour had any implications for future conduct, a decision for no further action, or a warning or reprimand might be sufficient.
Deficiency in myeloid differentiation factor-2 and toll-like receptor 4 expression attenuates nonalcoholic steatohepatitis and fibrosis in mice
Authors: Csak Timea , Velayudham Arumugam , Hritz Istvan , Petrasek Jan , Levin Ivan , Lippai Dora , Catalano Donna , Mandrekar Pranoti , Dolganiuc Angela , Kurt-Jones Evelyn , Szabo Gyongyi
Published: January 2011

Toll-like receptor 4 (TLR4) and its coreceptor, myeloid differentiation factor-2 (MD-2), are key in recognition of lipopolysaccharide (LPS) and activation of proinflammatory pathways. Here we tested the hypothesis that TLR4 and its coreceptor MD-2 play a central role in nonalcoholic steatohepatitis (NASH) and liver fibrosis in nonalcoholic fatty liver disease. Mice of control genotypes and those deficient in MD-2 or TLR4 [knockout (KO)] received methionine choline-deficient (MCD) or methionine choline-supplemented (MCS) diet. In mice of control genotypes, MCD diet resulted in NASH, liver triglycerides accumulation, and increased thiobarbituric acid reactive substances, a marker of lipid peroxidation, compared with MCS diet. These features of NASH were significantly attenuated in MD-2 KO and TLR4 KO mice. Serum alanine aminotransferase, an indicator of liver injury, was increased in MCD diet-fed genotype controls but was attenuated in MD-2 KO and TLR4 KO mice. Inflammatory activation, indicated by serum TNF-α and nictoinamide adenine dinucleotide phosphate oxidase complex mRNA expression and activation, was significantly lower in MCD diet-fed MD-2 KO and TLR4 KO compared with corresponding genotype control mice. Markers of liver fibrosis [collagen by Sirius red and α-smooth muscle actin (SMA) staining, procollagen-I, transforming growth factor-β1, α-SMA, matrix metalloproteinase-2, and tissue inhibitor of matrix metalloproteinase-1 mRNA] were attenuated in MD-2 and TLR4 KO compared with their control genotype counterparts. In conclusion, our results demonstrate a novel, critical role for LPS recognition complex, including MD-2 and TLR4, through NADPH activation in liver steatosis, and fibrosis in a NASH model in mice.
Ectonucleotidases in the digestive system: focus on NTPDase3 localization
Authors: Lavoie Elise G. , Gulbransen Brian D. , Martín-Satué Mireia , Aliagas Elisabet , Sharkey Keith A. , Sévigny Jean
Published: January 2011

Extracellular nucleotides and adenosine are biologically active molecules that bind members of the P2 and P1 receptor families, respectively. In the digestive system, these receptors modulate various functions, including salivary, gastric, and intestinal epithelial secretion and enteric neurotransmission. The availability of P1 and P2 ligands is modulated by ectonucleotidases, enzymes that hydrolyze extracellular nucleotides into nucleosides. Nucleoside triphosphate diphosphohydrolases (NTPDases) and ecto-5′-nucleotidase are the dominant ectonucleotidases at physiological pH. While there is some information about the localization of ecto-5′-nucleotidase and NTPDase1 and -2, the distribution of NTPDase3 in the digestive system is unknown. We examined the localization of these ectonucleotidases, with a focus on NTPDase3, in the gastrointestinal tract and salivary glands. NTPDase1, -2, and -3 are responsible for ecto-ATPase activity in these tissues. Semiquantitative RT-PCR, immunohistochemistry, and in situ enzyme activity revealed the presence of NTPDase3 in some epithelial cells in serous acini of salivary glands and mucous acini and duct cells of sublingual salivary glands, in cells from the stratified esophageal and forestomach epithelia, and in some enteroendocrine cells of the gastric antrum. Interestingly, NTPDase2 and ecto-5′-nucleotidase are coexpressed with NTPDase3 in salivary gland cells and stratified epithelia. In the colon, neurons express NTPDase3 and glial cells express NTPDase2. Ca2+ imaging experiments demonstrate that NTPDases regulate P2 receptor ligand availability in the enteric nervous system. In summary, the specific localization of NTPDase3 in the digestive system suggests functional roles of the enzyme, in association with NTPDase2 and ecto-5′-nucleotidase, in epithelial functions such as secretion and in enteric neurotransmission.
Hydrogen sulfide mitigates transition from compensatory hypertrophy to heart failure
Authors: Givvimani Srikanth , Munjal Charu , Gargoum Riyad , Sen Utpal , Tyagi Neetu , Vacek Jonathan C. , Tyagi Suresh C.
Published: January 2011

We reported previously that although there is disruption of coordinated cardiac hypertrophy and angiogenesis in transition to heart failure, matrix metalloproteinase (MMP)-9 induced antiangiogenic factors play a vital role in this process. Previous studies have shown the cardioprotective role of hydrogen sulfide (H2S) in various cardiac diseases, but its role during transition from compensatory hypertrophy to heart failure is yet to be unveiled. We hypothesize that H2S induces MMP-2 activation and inhibits MMP-9 activation, thus promoting angiogenesis, and mitigates transition from compensatory cardiac hypertrophy to heart failure. To verify this, aortic banding (AB) was created to mimic pressure overload in wild-type (WT) mice, which were treated with sodium hydrosulfide (NaHS, H2S donor) in drinking water and compared with untreated control mice. Mice were studied at 3 and 8 wk. In the NaHS-treated AB 8 wk group, the expression of MMP-2, CD31, and VEGF was increased while the expression of MMP-9, endostatin, angiostatin, and tissue inhibitor of matrix metalloproteinase (TIMP)-3 was decreased compared with untreated control mice. There was significant reduction in fibrosis in NaHS-treated groups. Echocardiograph and pressure-volume data revealed improvement of cardiac function in NaHS-treated groups over untreated controls. These results show that H2S by inducing MMP-2 promotes VEGF synthesis and angiogenesis while it suppresses MMP-9 and TIMP-3 levels, inhibits antiangiogenic factors, reduces intracardiac fibrosis, and mitigates transition from compensatory hypertrophy to heart failure.
Differential atrophy of the postero-lateral hip musculature during prolonged bedrest and the influence of exercise countermeasures
Authors: Miokovic Tanja , Armbrecht Gabriele , Felsenberg Dieter , Belavý Daniel L.
Published: January 2011

As part of the 2nd Berlin BedRest Study (BBR2-2), we investigated the pattern of muscle atrophy of the postero-lateral hip and hamstring musculature during prolonged inactivity and the effectiveness of two exercise countermeasures. Twenty-four male subjects underwent 60 days of head-down tilt bedrest and were assigned to an inactive control (CTR), resistive vibration exercise (RVE), or resistive exercise alone (RE) group. Magnetic resonance imaging (MRI) of the hip and thigh was taken before, during, and at end of bedrest. Volume of posterolateral hip and hamstring musculature was calculated, and the rate of muscle atrophy and the effect of countermeasure exercises were examined. After 60 days of bedrest, the CTR group showed differential rates of muscle volume loss ( F = 21.44; P ≤ 0.0001) with fastest losses seen in the semi-membranosus, quadratus femoris and biceps femoris long head followed by the gluteal and remaining hamstring musculature. Whole body vibration did not appear to have an additional effect above resistive exercise in preserving muscle volume. RE and RVE prevented and/or reduced muscle atrophy of the gluteal, semi-membranosus, and biceps femoris long head muscles. Some muscle volumes in the countermeasure groups displayed faster recovery times than the CTR group. Differential atrophy occurred in the postero-lateral hip musculature following a prolonged period of unloading. Short-duration high-load resistive exercise during bedrest reduced muscle atrophy in the mono-articular hip extensors and selected hamstring muscles. Future countermeasure design should consider including isolated resistive hamstring curls to target this muscle group and reduce the potential for development of muscle imbalances.