bluuebunny/crossref_metadata_2025 huggingface dataset:
Tobacco use and psychosis risk in persons at clinical high risk
Authors: Ward Heather B. , Lawson Michael T. , Addington Jean , Bearden Carrie E. , Cadenhead Kristin S. , Cannon Tyrone D. , Cornblatt Barbara A. , Jeffries Clark D. , Mathalon Daniel H. , McGlashan Thomas H. , Seidman Larry J. , Tsuang Ming T. , Walker Elaine F. , Woods Scott W. , Perkins Diana O.
Published: October 2018

Aim

To evaluate the role of tobacco use in the development of psychosis in individuals at clinical high risk.

Method

The North American Prodrome Longitudinal Study is a 2‐year multi‐site prospective case control study of persons at clinical high risk that aims to better understand predictors and mechanisms for the development of psychosis. The cohort consisted of 764 clinical high risk and 279 healthy comparison subjects. Clinical assessments included tobacco and substance use and several risk factors associated with smoking in general population studies.

Results

Clinical high risk subjects were more likely to smoke cigarettes than unaffected subjects (light smoking odds ratio [OR] = 3.0, 95% confidence interval [CI] = 1.9‐5; heavy smoking OR = 4.8, 95% CI = 1.7‐13.7). In both groups, smoking was associated with mood, substance use, stress and perceived discrimination and in clinical high risk subjects with childhood emotional neglect and adaption to school. Clinical high risk subjects reported higher rates of several factors previously associated with smoking, including substance use, anxiety, trauma and perceived discrimination. After controlling for these potential factors, the relationship between clinical high risk state and smoking was no longer significant (light smoking OR = 0.9, 95% CI = 0.4‐2.2; heavy smoking OR = 0.3, 95% CI = 0.05‐2.3). Moreover, baseline smoking status (hazard ratio [HR] = 1.16, 95% CI = 0.82‐1.65) and categorization as ever smoked (HR = 1.3, 95% CI = 0.8‐2.1) did not predict time to conversion.

Conclusion

Persons at high risk for psychosis are more likely to smoke and have more factors associated with smoking than controls. Smoking status in clinical high risk subjects does not predict conversion. These findings do not support a causal relationship between smoking and psychosis.
Changes to indications for tunneled cuffed catheter use in hemodialysis patients: A single‐center experience
Authors: Okamoto Takeshi , Sakurada Tsutomu , Koitabashi Kenichiro , Shibagaki Yugo
Published: October 2018

Introduction: As the number of elderly end‐stage renal disease patients lacking suitable vessels for arteriovenous fistula (AVF) is increasing, indications for tunnel cuffed catheters (TCCs) may be expanding. This study aimed to clarify changes over time in the number of patients with TCC and indications for TCCs.

Methods: This single‐center retrospective study analyzed 143 catheters for 95 patients who inserted TCCs between July 2005 and July 2017. Patients were divided into two groups (early‐ and late‐phase groups) based on the median observational period. Demographic data and clinical information were then compared.

Findings: Fifty TCCs were inserted in the early phase group, and 93 TCCs were inserted in the late‐phase group. The late‐phase group was older (77 vs. 70 years; P = 0.003) and showed a higher frequency of hypertensive nephropathy (29% vs. 14%; P < 0.05) and a lower frequency of a history of cardiovascular disease (52.7% vs. 70.0%; P = 0.045). In the late‐phase group, indications for bridge vascular access (0% vs. 11.8%; P < 0.05) or severe cardiac dysfunction (8.0% vs. 20.5%; P < 0.05) were increased. In addition, the late‐phase group showed increases in percentage of patients with the catheter inserted in the femoral vein (10.0% vs. 23.7%; P = 0.047), nephrologists performing catheter insertion (56.0% vs. 87.1%; P < 0.001), and the patients who underwent superficialization of the brachial artery (28.0% vs. 46.2%; P = 0.034). Significant differences in catheter survival, incidence of complications, reasons for catheter removal, or incidence of catheter‐related infection were not observed between groups.

Discussion: Patients with indications for TCC may be increasing due to an increase in elderly end‐stage renal disease patients whose activities of daily living have decreased. In addition, indications for bridge vascular access were widely accepted in the late‐phase group.
Hydrothermal synthesis of Litchi‐like SrTiO3 with the help of ethylene glycol
Authors: Zhao Wei , Wang Hugang , Liu Nianqi , Rong Jiacheng , Zhang Qi , Li Mingxiao , Yang Xianfeng
Published: October 2018

Templated by TiO2 microspheres, litchi‐like SrTiO3 crystals with a narrow size distribution and monodispersity were synthesized through the combination of regulating the ethylene glycol concentration during the hydrothermal process and the post heat treatment. The results show that when the volume ratio of water and ethylene glycol reached 10:70, microsized SrCO3 was firstly formed under the hydrothermal process, and then the litchi‐like SrTiO3 powder was obtained after the postheat treatment at 700°C for 4 hours, which shows a large specific surface area of 37.41 m2/g. It is found that the concentration of ethylene glycol aqueous solution plays an important role on the morphology of the SrTiO3 crystals, and the slightly higher viscosity and proper amount of OH hydroxyl groups facilitate the formation of the micrometer spherical hierarchical surface.
Funding Value Adjustments
Authors: ANDERSEN LEIF , DUFFIE DARRELL , SONG YANG
Published: October 2018

In this paper, we demonstrate that the funding value adjustments (FVAs) of major dealers are debt overhang costs to their shareholders. To maximize shareholder value, dealer quotations therefore adjust for FVAs. Our case studies include interest‐rate swap FVAs and violations of covered interest parity. Contrary to current valuation practice, FVAs are not themselves components of the market values of the positions being financed. Current dealer practice does, however, align incentives between trading desks and shareholders. We also establish a pecking order for preferred asset financing strategies and provide a new interpretation of the standard debit value adjustment.
Characterizing pharmacist prescribers in Alberta using cluster analysis
Authors: Faruquee Chowdhury F. , Guirguis Lisa M. , Hughes Christine A. , Makowsky Mark J. , Sadowski Cheryl A. , Schindel Theresa J. , Cor Ken M. , Yuksel Nese
Published: October 2018

Objectives

Legislative and regulatory bodies in Canada have authorized pharmacists to prescribe in different provinces. Albertan pharmacists have the broadest prescribing scope. Our objective was to cluster Albertan pharmacists into different prescriber groups based on their self-reported prescribing practice and to compare the groups according to practice settings, the proportion of Additional Prescribing Authority (APA) pharmacists and support experiences.

Methods

A cross-sectional survey was administered among a sample of 700 Albertan practicing registered pharmacists in 2013 to identify their involvement in different types of prescribing activities. Cluster analysis was used to group participants based on their reported prescribing practices. Chi-squared test was used to compare prescriber groups by practice settings and the proportion of APA pharmacists. One-way analysis of variance was used to compare the groups by their support experiences.

Key findings

Three major groups of pharmacist prescriber were identified – ‘renewal prescriber’ (74%), ‘Modifier’ (17%) and ‘Wide ranged prescriber’ (9%). Prevalence of ‘renewal prescriber’ in the community setting was 85.8% whereas ‘Modifier’ was predominant (66.7%) in the collaborative setting. Higher support experience facilitated the wide range prescribing. Pharmacists with APA were most likely to be classified into ‘Modifier’ (17.6%) or ‘Wide ranged prescriber’ (13.8%) groups than the ‘renewal prescriber’ group (3.1%).

Conclusions

Although legislation allowed Albertan pharmacists to have the broadest scope of prescribing authority, few are practicing with the fullest scope. Prescribing practice varies based on practice setting and support experience. Future research could explore factors influencing the types of adoption and measure the shifting of prescribing type over time.
A Mid‐Range Theory of Control and Coordination in Service Triads
Authors: Bastl Marko , Johnson Mark , Finne Max
Published: October 2018

The increased frequency of the adoption of service‐based business models by manufacturers, such as solution provision, has given rise to service triads. While there is consensus that actors in service triads are relationally and performatively interdependent, less is understood about how service triads are controlledandcoordinated. In this study, we use an inductive case‐based approach to build an understanding about the roles, approaches, and contextual factors that influence how service triads are controlled and coordinated. We collected and analyzed data from nine companies forming three service triads, each comprising a customer, a manufacturer of an asset, and a service supplier. We synthesized our findings in a theoretical framework, where we show that first, both, controlandcoordination, are present in service triads rather than just control as previously posited. Second, controlling and coordinating service triads is not a single actor's responsibility but rather a collective effort shared by two or three actors. Third, we uncovered four contingent factors that influence the dynamics of how service triads are controlled and coordinated: the customer's risk exposure due to the offering's failure, the substitutability of the offering, the contractual safeguards, and the relationship closeness.
Stalemate in the States: Agenda Control Rules and Policy Output in American Legislatures
Authors: Crosson Jesse M.
Published: October 2018

This article examines how the power of majority‐party leaders to set the legislative voting calendar influences policy change in American state legislatures. By generating an opportunity for party leaders to exercise gatekeeping or negative agenda control, such rules introduce an additional partisan veto player into a system of governance. This addition typically increases the size of the core or gridlock interval, which drives policy change downward. Using both traditional data on bill passage counts and new data on Affordable Care Act compliance, I find strong support for these claims. More specifically, when I calculate core sizes that are sensitive to agenda rules, I find that agenda‐control‐adjusted core size is negatively correlated with policy change, as expected. Moreover, even when I match states on their overall preference dispersion or polarization, the ability of party leaders to exercise negative agenda control is strongly negatively associated with policy change.
What Is Philosophy? Prolegomena to a Sociological Metaphilosophy
Authors: Norrie Stephen J. E.
Published: October 2018

The question “What is philosophy?” is difficult to answer because it seems to presuppose answers to long‐standing and controversial philosophical questions. As answers to these questions affect one’s metaphilosophy, apparently irresolvable philosophical disagreements are then converted into deadlock concerning the nature of the discipline. As this problem is unique to philosophy, however, this difficulty itself reveals something of philosophy’s essential nature. As, under analysis, it turns out to arise from a definite way of posing problems, philosophy can initially be defined by a particular mode of problematisation. This essay establishes this argument and proposes a method for developing this insight into a fully realised, socio‐historical metaphilosophy. This involves stages of (a) hermeneutical analysis and (b) historical contextualisation, both of which increase the account’s empirical adequacy. A conclusion discusses the extent to which philosophy is on trial here and argues that questioning the future of philosophy is not inherently philistine.
How (Not) to Theorize About Multiple Realization
Authors: Barrett David
Published: October 2018

Though multiple realization has been an important concept in the philosophy of mind and philosophy of psychology for more than fifty years, it has not been until quite recently that anyone proposed an actual theory of what multiple realization is. This paper argues that the most dominant current theories of multiple realization are unacceptable. It does so by mainly arguing for a particular methodology for theorizing about multiple realization. Rather than being mostly constrained by intuitions, as theorizing about folk notions usually is, theorizing about multiple realization is, it argues, constrained by the theoretical context in which the concept was born. By the lights of this method for constructing theories of multiple realization, these current theories are unacceptable.
The density of odontocete integument depends on blubber lipid composition and temperature
Authors: Lonati Gina L. , Singleton Emily M. , Phelps Caitlin E. , Koopman Heather N. , Pabst D. Ann
Published: October 2018

Cetacean integument serves many functional roles, including contribution to whole body buoyancy. The blubber of the integument of different cetacean species contains varying concentrations of triacylglycerols (TAG) and wax esters (WE); generally, these lipid classes have different densities. Integument can also experience a wide range of temperatures during a dive, so its density may change with depth. The goals of this study were to measure integument density and isolated blubber lipid density in three deep‐diving odontocete species (n = 3–4)—short‐finned pilot whales (Globicephala macrorhynchus), pygmy sperm whales (Kogia breviceps), and Gervais' beaked whales (Mesoplodon europeaus)—at different temperatures (6°C–35°C), and to relate these densities to lipid content and composition. Kogia and Mesoplodon integument and isolated lipids had high WE content (78.7–99.5 wt%) and were less dense (by 1.7%–9.3%) than those of Globicephala, which were composed predominately of TAG. Generally, densities increased as temperature decreased. Changes in integument densities mirrored those of isolated lipid densities, suggesting that blubber lipids are largely responsible for the buoyant properties of cetacean integument. These data demonstrate that the contribution of the integument to whole body density depends on lipid class and temperature, and therefore may provide useful, species‐specific correction factors for diving energetics models.
Tafamidis improves bladder function in hereditary ATTR amyloidosis
Authors: Lee Fang‐Ching , Sakakibara Ryuji , Tateno Fuyuki , Aiba Yosuke , Kishi Masahiko , Suzuki Hiroyoshi , Shimizu Ayami , Takahashi Osamu , Takada Nobuo
Published: October 2018

A 71‐year‐old man with a family history of hereditary ATTR (ATTRm) amyloidosis, began to have sensory disturbance in his extremities at age 65. Although he had no cardiac or gastrointestinal symptoms, a head‐up tilt test, ultrasound echography, myocardial scintigraphy, and upper gastric biopsy showed abnormality. This, together with the findings of nerve conduction study and gene analysis, confirmed a diagnosis of ATTRm. He was started on 20 mg/day tafamidis meglumine, a transthyretin tetramer stabilizer, and 0.5 mg/day clonazepam, a GABAergic drug. Somatic nerve functions were unchanged or slightly worsened. However, his bladder autonomic nerve function, as assessed by a urodynamic test, showed mild improvements characterized by recovery of bladder sensation and contractility.
Heart‐rate modulations reveal attention and consciousness interactions
Authors: Cobos María I. , Guerra Pedro M. , Vila Jaime , Chica Ana B.
Published: October 2018

Our environment is constantly overloaded with information, although we cannot consciously process all the stimulation reaching our senses. Current theoretical models are focused on the cognitive and neural processes underlying conscious perception. However, cognitive processes do not occur in an isolated brain but in a complex interaction between the environment, the brain, and the organism. The brain‐body interaction has largely been neglected in the study of conscious perception. The aim of the present study was to explore if heart rate and skin conductance (SC) are modulated by the interaction between phasic alertness and conscious perception. We presented near‐threshold visual stimuli that could be preceded by an alerting tone on 50% of the trials. Behaviorally, phasic alerting improved perceptual sensitivity for detecting a near‐threshold stimulus (along with changes in response criterion). Following the alerting tone, a cardiac deceleration‐acceleration pattern was observed, which was more pronounced when the near‐threshold stimulus was consciously perceived in comparison with unconsciously perceived stimuli. SC results further showed some degree of subliminal processing of unseen stimuli. These results reveal that cardiac activity could be a marker of attention and consciousness interactions, emphasizing the need for taking into account brain‐body interactions for current theoretical models of consciousness.
On Cross-Validation for Sparse Reduced Rank Regression
Authors: She Yiyuan , Tran Hoang
Published: October 2018

In high dimensional data analysis, regularization methods pursuing sparsity and/or low rank have received much attention recently. To provide a proper amount of shrinkage, it is typical to use a grid search and a model comparison criterion to find the optimal regularization parameters. However, we show that fixing the parameters across all folds may result in an inconsistency issue, and it is more appropriate to cross-validate projection–selection patterns to obtain the best coefficient estimate. Our in-sample error studies in jointly sparse and rank deficient models lead to a new class of information criteria with four scale-free forms to bypass the estimation of the noise level. By use of an identity, we propose a novel scale-free calibration to help cross-validation to achieve the minimax optimal error rate non-asymptotically. Experiments support the efficacy of the methods proposed.
Results and Reasons of Failure at the Secondary Level Examination of Bangladesh Education System: An Empirical Investigation
Authors: Hossain Md. Amir
Published: October 2018

The aim of this research paper is to look at the results and reasons of failure of the SSC, Dakhil, and Vocational Examinations-2018 under 10 Education Boards in Bangladesh. It would like to unveil the 21st-century Education System of the secondary level. Its aim is to highlight all sorts of Subjects of Humanities, Business Studies, and Science Group at the secondary level. It attempts to investigate the total students of all education boards, reasons of failure, comparative study of pass rate, the number of successful students with GPA-5, and their average percentage of each board. This study would like to focus on the real picture of teachers’ and students’ performance at the secondary level. For this purpose, the current researcher had to complete the survey with the help of 20 participants, including 10 students, 5 teachers, and 5 parents regarding results and failure of the secondary level examination based on questionnaire system at Sristy Central School & College, Uttara, Dhaka. Sources were taken from the selected national dailies of Bangladesh. Teachers, students, and parents were asked to tick the right option out of four about the current education system of the secondary level. Based on their comments, the researcher had to find out the probable means of solution. Moreover, the aim of the paper is to investigate the effective recommendations for learners, parents, and teachers with a view to showing a new dimension of the secondary level education system of Bangladesh.
Mitochondrial ATP synthase β‐subunit production rate and ATP synthase specific activity are reduced in skeletal muscle of humans with obesity
Authors: Tran Lee , Langlais Paul R. , Hoffman Nyssa , Roust Lori , Katsanos Christos S.
Published: October 2018

New Findings

What is the central question of this study?

Humans with obesity have lower ATP synthesis in muscle along with lower content of the β‐subunit of the ATP synthase (β‐F1‐ATPase), the catalytic component of the ATP synthase. Does lower synthesis rate of β‐F1‐ATPase in muscle contribute to these responses in humans with obesity?

What is the main finding and its importance?

Humans with obesity have a lower synthesis rate of β‐F1‐ATPase and ATP synthase specific activity in muscle. These findings indicate that reduced production of subunits forming the ATP synthase in muscle may contribute to impaired generation of ATP in obesity.

The content of the β‐subunit of the ATP synthase (β‐F1‐ATPase), which forms the catalytic site of the enzyme ATP synthase, is reduced in muscle of obese humans, along with a reduced capacity for ATP synthesis. We studied 18 young (37 ± 8 years) subjects of which nine were lean (BMI = 23 ± 2 kg m−2) and nine were obese (BMI = 34 ± 3 kg m−2) to determine the fractional synthesis rate (FSR) and gene expression of β‐F1‐ATPase, as well as the specific activity of the ATP synthase. FSR of β‐F1‐ATPase was determined using a combination of isotope tracer infusion and muscle biopsies. Gene expression of β‐F1‐ATPase and specific activity of the ATP synthase were determined in the muscle biopsies. When compared to lean, obese subjects had lower muscle β‐F1‐ATPase FSR (0.10 ± 0.05 vs. 0.06 ± 0.03% h−1; P < 0.05) and protein expression (P < 0.05), but not mRNA expression (P > 0.05). Across subjects, abundance of β‐F1‐ATPase correlated with the FSR of β‐F1‐ATPase (P < 0.05). The specific activity of muscle ATP synthase was lower in obese compared to lean subjects (0.035 ± 0.004 vs. 0.042 ± 0.007 arbitrary units; P < 0.05), but this difference was not significant after the activity of the ATP synthase was adjusted to the β‐F1‐ATPase content (P > 0.05). Obesity impairs the synthesis of β‐F1‐ATPase in muscle at the translational level, reducing the content of β‐F1‐ATPase in parallel with reduced capacity for ATP generation via the ATP synthase complex.
Ferropenia sin anemia, más que un hallazgo de laboratorio
Authors: Martín Arsanios Daniel , Serrano Samuel , Espinel Bayron , Quintero Elias , Rincón María José , Bastidas Goyes Alirio
Published: October 2018

El déficit de hierro sin anemia se encuentra presente en diversas patologías de la práctica clínica; sin embargo, se conoce poco sobre la importancia, las complicaciones y los beneficios de su tratamiento. Este artículo describe la evidencia actual sobre distintas vías fisiopatológicas, abordaje y tratamiento de las principales patologías relacionadas con la ferropenia sin anemia. Para ello se realizó una búsqueda completa y actualizada de la literatura científica en Medline, OVID, Lilacs, SciELO y EMBASE utilizando una estrategia definida con términos MeSH y no MeSH, limitado a español e inglés.
Creencias islámicas respecto a la muerte y análisis sobre su impacto en la donación humana
Authors: Laurens Acevedo Lysha Michelle , Lince Rivera Isabella , Pérez Angélica María , Jiménez Sánchez Sebastian , Kunzel Gallo Alexa , Lastra Santiago María Alejandra
Published: October 2018

El islam surgió a principios del siglo VII, al este de la península arábiga, cuando Mahoma, el profeta, tuvo revelaciones del arcángel Gabriel y, consecuentemente, propuso el nacimiento de este modo de vida basado en el sometimiento a la voluntad de Alá. Las creencias alrededor de esta religión han cruzado fronteras, debido a la migración voluntaria o forzosa de su comunidad, hecho que ha marcado una influencia sociocultural de gran magnitud en sus creyentes respecto a la muerte y, por ende, a la donación humana de órganos y tejidos para trasplante. Por este motivo, su estudio constituye un tema de gran interés para los profesionales de la salud, dado que hay percepciones que influyen directamente en la concepción de sus fieles. Se tiene en cuenta el cuerpo como un ente sagrado, símbolo de la integración del alma, materia, ego e intelecto con una resurrección que podría comprometer su integridad en el proceso de donación. Sin embargo, las grandes instituciones en materia de bioética islámica respaldan que prima la obligación moral de solidaridad universal que conlleva hacerle el bien al prójimo, siempre y cuando no se infrinja un daño al ser propio.
Mycobacterium nonchromogenicum en un paciente con neumoconiosis: reporte de un caso en atención primaria
Authors: Villadiego Cortina Alejandra Melisa , Pardo Rubio Ernesto
Published: October 2018

La neumoconiosis es una patología pulmonar crónica producida por el daño tisular que originan algunos tóxicos al ser inhalados durante ciertos periodos. El caso presentado corresponde a un paciente inmunocompetente con silicoantracosis, un tipo de neumoconiosis, en quien se detecta infección pulmonar por Mycobacterium nonchromogenicum en un centro de atención primaria en Bogotá, Colombia, poco común y de gran interés médico.
Consideration on Tempering and PWHT Temperatures of C-Mn and Low Alloy Steels Used for the Fabrication of Pressure Vessels: Smart Tuning of Heat Treatment Parameters
Authors: Pillot Sylvain , Sakata Mikihiro , Coudreuse Lionel , Ngomo Valéry
Published: October 2018

For many years, process licensors and/or end-users have frequently specified that the tempering temperature of C-Mn alloys and low alloy steels (i.e. Cr-Mo, Mn-Mo-Ni alloys) should be greater than the post-weld heat treatments (PWHT). Most of the time, tempering temperature is then required as much as 30°C (54°F) above the PWHT temperature, making it very difficult for steelmakers to be able to supply compliant materials, especially for heavy wall components.

Application of rules in the applicable codes often leads steelmakers to request for deviations in cases where they become not compatible with material capabilities. This report is intended to illustrate the combined effect of tempering and PWHT on materials properties and to provide recommendations on how to tune smart the tempering treatment with the aim of proposing the most efficient complete heat treatment sequence.

Data provided within this paper for C-Mn steels and low alloy grades (Cr-Mo and Mn-Mo-Ni alloys) prove that tempering can be performed at temperatures below, at or above one of PWHT without any adverse effect. Data from actual mill production records show that stringent material specifications can be met by steelmakers when they are allowed to tune smartly the heat treatment parameters (tempering temperature) in accordance with applicable construction codes.

The data also demonstrate that limiting the tempering temperature in the lower range of allowed temperatures may be beneficial to customers as it gives more safety margins for fabrication and maintenance (i.e. potential repairs/modifications) of pressure vessels. It permits either to consider more cycles for PWHT or to perform PWHT at higher temperatures or for longer durations, while on the opposite, current trend imposing high tempering temperatures limits flexibility.
Advanced Signal Processing Techniques for Guided Wave Corrosion Monitoring System in Secondary Circuits of Nuclear Power Plants
Authors: Gribok Andrei , Agarwal Vivek
Published: October 2018

This paper describes the application of independent component analysis (ICA) to detect corrosion-induced defects in commercial nuclear power plants. This paper analyzes the applicability and benefits of ICA when applied to guided wave (GW) technology to detect corrosion in secondary circuits, as well as studying the potential for expanding the range of GW technology to include complex geometries and piping components. The ultrasonic GWs can inspect long stretches of straight piping; however, more complex geometries that include elbows, welds, and tees are causing spurious reflections and coherent noise, which significantly decreases the sensitivity of the GW systems. The potential of ICA to improve detection sensitivity is analyzed and practical recommendations are provided. It is demonstrated on GW data collected at one of the commercial nuclear power plants that ICA, under certain conditions, is capable of separating different coherent noise components and has potential for improving signal-to-noise ratio.
Buckling of Tanks With a Conical Roof Under Harmonic Settlement
Authors: Fan Haigui , Wang Zewu , Yan Kun
Published: October 2018

Buckling behavior of tanks with a conical roof under harmonic settlement has been researched in this paper. A real tank in engineering is taken into account and the harmonic settlement is applied to the bottom of the tank to simulate its buckling behavior. Results show that the tank wall will be subjected to a deformation mutation when the settlement reaches a critical value. It means that compared to the conical roof, the tank wall is more vulnerable to buckling. Because of the complexity added by the grid of rafters and rings on the roof, two different simplified models are presented. For the first model, the tank’s roof is modified to an equivalent thickness based on the smeared method; for the other one, the roof is completely eliminated and its influence is represented by simply supported boundary conditions at the top of the tank wall. Analysis shows that the tank model without a roof can’t reflect buckling behavior of the real tank in engineering very well. While the model with an equivalent thickness roof can avoid this deficiency and achieve high efficiency and accuracy. It’s recommended to be applied to buckling analysis of tanks under settlement. Based on that, effects of wave numbers on the critical settlement for the three models are researched and compared. Result shows that the simplified tank model with an equivalent thickness roof presented in this paper is efficient and useful for buckling analysis of tanks with a conical roof under settlement.
Hydrogen Transfer Line Structural Analysis
Authors: Rosenblad Peter M. , Buchanan L. P. , Bett C. R.
Published: October 2018

This paper presents the design and analysis of the Hydrogen Transfer Lines (HTL) in the Spallation Neutron Source Facility (SNS), Oak Ridge National Laboratory in Oak Ridge, Tennessee. SNS is a Neutron Accelerator providing intense pulsed neutron beams for scientific research into the behavior of materials. The use of supercritical Hydrogen provides moderation of these neutron beam lines. This is facilitated by the HTL, which consists of six coaxial tubes transporting supercritical hydrogen to and from the Moderators surrounding the Mercury Target inside the Core Vessel (CV). Each Hydrogen line is surrounded by a vacuum tube in order to preserve the supercritical Hydrogen temperature of −425°F (−254° C/19 K). An inert Helium tube and a Water Jacket surround the Outer Vacuum Jacket.

The Hydrogen boundary is considered the primary containment boundary, with the vacuum tubing being the secondary containment boundary both considered to be safety significant. The HTL assembly tubing must be qualified as Performance Category 3 to the requirements of Department of Energy Standard 1020-1994 for Natural Phenomena Hazards. This requires a detailed dynamic analysis. The HTL must also be qualified to ASCE 43-05 for Limit State consideration for abnormal events and ASME B31.3 for sustained and occasional (upset) loadings. The design basis includes consideration of normal sustained loadings such as deadweight and pressure, as well as thermal expansion/contraction, a Design Basis Earthquake (DBE) with associated Anchor Movements (SAM) and the potential physical interaction between coaxial tubes. Intermittent spacers are provided between some of the tubes, providing a functional interspace between the Hydrogen tubing and the Vacuum Jackets. The analytical methodology involves supplementing unaddressed criteria per ASME B31.3 thus requiring the application of more detailed rules found in ASME Section III, NC-3600, ASCE/SEI 43 – 05 as well as Regulatory Requirements such as USNRC Regulatory Guide 1.61 and 1.92. To assess the potential of a postulated failure of the primary Hydrogen boundary inside the Core Vessel, NUREG 0800, Section 3.6.3, Leak-Before-Break Evaluation Procedures are employed.
Pressure Temperature Ratings of Aluminum Alloy Flanges
Authors: Xu Kang , Rana Mahendra D.
Published: October 2018

ASME B31.3 Appendix L provides the pressure and temperature ratings of forged aluminum flanges. The flanges are from NPS 1/2 to NPS 24 in three rating Classes 150, 300 and 600 with two grades of aluminum alloys: ASTM B247 3003-H112 and 6061-T6. However, B31.3 does not provide any technical information on the basis of the pressure and temperature ratings. A review of the historical development of ASME B16.5 indicated that the aluminum flanges had the same technical basis for pressure and temperature ratings as the ferrous alloy flanges in ASME B16.5. The 1960 Addenda of the 1957 Edition B16.5 included both aluminum flanges and ferrous alloy flanges. A new Code Case 2905 has been recently approved to allow B31.3 Appendix L aluminum flanges in fabricating Section VIII Division 1 pressure vessels as B16.5 flanges on the basis that both flange specifications have the same safety margin. In this paper, the technical basis of the pressure and temperature rating of aluminum flanges is revisited. Based on the same principle, the pressure ratings are extended to Class 900 and Class 1500 for the two aluminum alloys using the same analysis. Since ASTM B247 5083-H112 is another common grade of aluminum forging alloy, the pressure and temperature ratings are proposed for 5083-H112.
The Influence of Elevated Temperature in Creep Relaxation of Various PTFE Gaskets Production Methods
Authors: Silva Ana C. , Werner Florian , Xavier Lucas
Published: October 2018

Polytetrafluoroethylene (PTFE) products have been widely used for industrial sealing applications due to their outstanding chemical resistance as well as their electrical, anti-stick, impact resistance and low friction properties. Diverse PTFE flat gaskets production methods are available in the industry, which include the combination of a selected Resin Type and a determined manufacturing process, being able to provide a wide range of several types of PTFE gaskets, with different mechanical characteristics.

The production method has significant impact on the mechanical properties of the PTFE gaskets, especially the creep relaxation property at elevated temperatures. Therefore, the gasket behavior at high temperatures and, consequently, the bolted flanged joint (BFJ) performance, directly depends on both selected Resin Type and gasket manufacturing process.

One of the most used PTFE gasket types is produced from multiaxially expanded PTFE sheets. As it is known, different types of stretching, among other factors, confer to the gasket particular mechanical characteristics. This type of gasket exhibits a very low gasket seating stress, and it is the preferred type for most low bolt load flanges.

This paper presents a study of the creep relaxation property at room and elevated temperatures of expanded PTFE gaskets manufactured by different Resin Types and processes of expanding PTFE materials. Experimental results are presented comparing EN 13555 [1] Qsmax, PQR and ΔeGc parameters of the produced PTFE gaskets.
The Mechanical Interaction of Clad and Base Metal for Molten Salt Reactor Structural Components
Authors: Messner M. C. , Phan V.-T. , Jetter R. I. , Sham T.-L.
Published: October 2018

Cladding structural components with a corrosion resistant material may greatly extend the design life of molten salt reactor concepts. A complete design methodology for such cladded, high temperature nuclear components will require addressing many issues: fabrication, corrosion resistance, metallurgical interaction, and the mechanical interaction of the clad and base materials under load. This work focuses on the final issue: the mechanical interaction of the base and clad under creep-fatigue conditions. Depending on the relative mechanical properties of the two materials the clad may substantially influence the long-term cyclic response of the structural system or its effect might be negligible. To quantify the effect of different clad material properties we develop an efficient method for simulating pressurized cladded components in the limiting case where the section of interest is far from structural discontinuities. Using this method we evaluate the mechanics of the clad/base system and identify different regimes of mechanical response. The focus is on situations relevant to high temperature nuclear components: thermal-cyclic Bree-type problems and similar axisymmetric structures. The insights gained from these structural studies will form the basis for developing design rules for high-temperature, nuclear, cladded components.
Detection of Ratcheting in Finite Element Calculations
Authors: Messner M. C. , Sham T.-L.
Published: October 2018

The distinction between a ratcheting and non-ratcheting response is critical for many high temperature design methods. Non-ratcheting is generally considered safe — deformation remain bounded over the lifetime of the component — while ratcheting is undesirable. As a particular example, the elastic perfectly-plastic (EPP) design methods described in recent ASME Section III, Division 5 code cases require a designer to distinguish ratcheting from non-ratcheting for finite element analyses using a relatively simple, elastic perfectly-plastic constitutive response. However, it can be quite difficult to distinguish these two deformation regimes using finite element (FE) analysis particularly in the case where the actual ratcheting strain is small. In practice FE analysis of structures that are analytically in either the plastic shakedown or ratcheting regimes will result in small, cycle-to-cycle accumulated strains characteristic of ratcheting. Distinguishing false ratcheting — the structure is actually in the plastic shakedown regime — from true ratcheting can be challenging. We describe the characteristics of nonlinear FE analysis that cause these false ratcheting strains and describe practical methods for distinguishing a ratcheting from a non-ratcheting response.
A Unified Inelastic Constitutive Model for the Average Engineering Response of Grade 91 Steel
Authors: Messner M. C. , Phan V.-T. , Sham T.-L.
Published: October 2018

Grade 91 steel has been called out for use in advanced reactor intermediate heat exchangers and other components. The material has good high temperature creep resistance and thermal properties but has a complex microstructure that manifests as cyclic softening, work softening, and tension/compression asymmetry in its engineering mechanical response. We describe a unified viscoplastic model for the deformation of Grade 91 for an expected operating temperature range spanning from room temperature to approximately 650°C. The model transitions from a rate independent response at low temperatures and high strain rates to a rate dependent, unified viscoplastic response at high temperatures and low creep strain rates. The model captures work and cyclic softening in the material through combined isotropic-kinematic hardening and captures observed tension/compression asymmetry and related anomalous ratcheting effects through a non-J2 flow term. A particular focus of the model is on capturing the average response of Grade 91 as determined from a wide collection of experimental data at many different temperatures, rather than the response of a single set of experiments at a particular temperature. The final model is suitable for the engineering design of nuclear components via inelastic analysis using the ASME Section III, Division 5 procedures.
Weld Rod Fatigue Analysis Using Effective Notch Stress Method
Authors: Karpanan Kumarswamy , Weber Kirk Allison , Hershman Gerald
Published: October 2018

Welds are one of the commonly used joint types and are employed extensively in subsea oil and gas production equipment. Commonly used weld joints in subsea components are fillet, butt, full-penetration, plug, and girth. Fatigue is one of the critical failure modes for welded joints. Welded joints are complex to analyze for fatigue loading due to the microstructure change during the welding process. The welding process also induces residual stress in the heat affected zone (HAZ) surrounding the weld. This, in turn, can adversely affects the fatigue life of the joint.

The S-N fatigue approach is commonly used for weld fatigue analysis due to the simplicity of this method. Industry standards such as DNV, IIW, BS-7608, and ASME BPVC Sec VIII Div. -2 or -3 are typical references for this type of analysis. For subsea specific applications, DNV-RP-C203 and BS-7608 are generally used because these two standards provide S-N curves for welds in “air” as well as in “seawater with cathodic protection”. These two codes also provide S-N curves for various weld geometries ranging from simple fillet welds to complex tubular joints. Some of the weld fatigue analysis techniques used in the subsea industry are the: nominal stress approach, structural hot spot stress approach, effective notch stress approach (ENS), structural stress method (ASME VIII-2, -3) and the Fracture mechanics based fatigue crack propagation (FCG) approach.

This paper presents the fatigue analysis of fillet welds in bore inserts using the ENS method. In the ENS method, a 1mm radius notch is modelled at the weld root or toe, see Figure 1, which yields a finite weld root stress. The stress analysis is carried out using FEA and the stresses on the notch along with the appropriate fatigue curve are used to estimate the weld root fatigue life.
Dynamic Fracture Behavior of 316L Brazed Joint: Study With Experimental and Finite Element Methods
Authors: Zhang Weiya , Jiang Wenchun , Yang Bin , Song Ming , Zhai Xiangnan
Published: October 2018

Brazed joints are widely used in the plate fin structures, and it is very important to ensure the strength under dynamic pressure. This paper investigated the dynamic fracture mechanism of 316L brazed joints using experimental and finite element method. Results show that the yield strength, tensile strength and elongation of the brazed joint are closely related with the strain rate. Using the finite element method, the strain rate sensitive model (Johnson-Cook) is built, and the brazed joint shows a multi-axial fracture mode. Meanwhile, the brazed residual stress and filler metal thickness affect the dynamic fracture behavior of the brazed joint.
Assessment of Heat-to-Heat Variation of Gr.91 Boiler Pipings by Small Punch Creep Test
Authors: Komazaki Shin-ichi , Obata Keisuke , Tomobe Masato , Yaguchi Masatsugu , Kumada Akihiro
Published: October 2018

The small punch (SP) testing technique was applied to five heats of Gr.91 steel, which had been actually used for boiler pipings in different ultra-super critical (USC) power plants for long periods of time, to investigate the applicability of this testing technique to the assessment of heat-to-heat variation of creep property. The SP creep test was carried out at the temperature of 650°C and under the loads of 190, 230, 300 N using a small disk-type specimen (ϕ 8 × 0.5 mm). The experimental results revealed that the SP creep rupture strength (rupture life) and the deformation rate were different depending on the heat. These differences were qualitatively in good agreement with those observed in the uniaxial creep test. The results obtained in this study indicated that the SP creep testing technique could be a strong tool for the assessment of heat-to-heat variation of in-service boiler pipings.
Efficiency Diagram Alternative Rule for Ratchetting: Historical Background, Overview, On-Going Developments
Authors: Martin A. , Pétesch C. , Lejeail Y. , Lamagnère P. , Lebarbé T. , Muñoz Garcia J. E. , Aiello G.
Published: October 2018

RCC-MRx Code is the result of the merger of the RCC-MX 2008, developed in the context of the research reactor Jules Horowitz Reactor project, and the RCC-MR 2007, which established rules applicable to the design of components operating at high temperature and to the Vacuum Vessel of ITER.

This code has been issued in French and English versions by AFCEN (Association Française pour les règles de Conception et de Construction des Matériels des Chaudières Electro-nucléaires) in 2012, 2015, and a new edition will be published by the end of 2018.

This new edition integrates a significant evolution for the rules dedicated to the ratchetting evaluation through the so-called “efficiency diagram rule”. This rule was initially developed to present a less penalizing rule than the classical “3 Sm” rule and to analyze the interaction between creep and ratchetting in the high temperature domain.

Since the first edition of RCC-MR code, several modifications have been made to this rule to improve its representativeness for this kind of damage. These modifications were motivated and justified by numerous experimental tests.

The last significant evolution is thus the occasion to present through this article, the background of this rule, the major evolutions already incorporated in the code and also the on-going developments.
Low Cycle Fatigue (EAF) of AISI 304L and 347 in PWR Water
Authors: Seppänen Tommi , Alhainen Jouni , Arilahti Esko , Solin Jussi
Published: October 2018

The update of the ASME III design fatigue curve for stainless steel in conjunction with the Fen model described in the NUREG/CR-6909 report has been criticized since publication. Data used to develop curves and models raises more questions than it answers.

Material testing in a simulated light water reactor environment is difficult due to the temperature and pressure involved. The experimental challenge makes it tempting to take shortcuts where they should least be taken. Facing and overcoming the challenges, direct strain-controlled fatigue testing has been performed at VTT using a unique tailored-for-purpose EAF facility. The applicable ASTM standards E 606 and E1012 are followed to provide results that are directly compatible with ASME Code Section III.

Several earlier PVP papers (PVP2016-63291, PVP2017-65374) report lower than calculated experimental Fen factors for stabilized stainless steels. In this paper new results, in line with the previous years’ conclusions, are presented for nonstabilized AISI 304L tested with dual strain rate waveforms.

To model environmental effects more accurately, an approach accounting for the damaging effect of plastic strain is proposed. A draft Fen model, similar in structure to the NUREG model but with additional parameters, is shown to significantly improve the accuracy of Fen prediction.