bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of an immersive virtual reality tour of the operating theater on emergence delirium in children undergoing general anesthesia: A randomized controlled trial
Authors: Ryu Jung‐Hee , Oh Ah‐Young , Yoo Hee‐Jeong , Kim Jin‐Hee , Park Jin‐Woo , Han Sung‐Hee
Published: October 2018

Background and Aims

An immersive virtual reality tour of the operating theater could reduce preoperative anxiety. This study was designed to determine whether a preoperative immersive virtual reality tour demonstrates a reduction in emergence delirium through reducing the preoperative anxiety in children undergoing general anesthesia.

Methods

Eighty‐six children were randomly allocated into either the control or virtual reality group. The control group received conventional education regarding the perioperative process. The virtual reality group watched a 4‐minute virtual reality video showing the operating theater and explaining the perioperative process. Incidence and severity of emergence delirium were the main outcomes. Secondary outcomes included preoperative anxiety using modified Yale Preoperative Anxiety Scale and postoperative behavioral disturbance.

Results

Eighty children completed the final analysis (control group = 39, virtual reality group = 41). The incidence (risk ratio [95% CI]: 1.1 [0.5‐2.8], P = 0.773) and severity of emergence delirium (mean difference [95% CI]: −0.2 [−2.7 to 2.2], P = 0.791) were similar in the two groups. After the intervention, children in the virtual reality group had a significantly lower modified Yale Preoperative Anxiety score than those in the control group (mean difference [95% CI]: 9.2 [0.3‐18.2], P = 0.022). No difference was observed regarding postoperative behavioral disturbance between the two groups at postoperative 1 day (mean difference [95% CI]: −0.1 [−0.3 to 0.1], P = 0.671) and 14 day (mean difference [95% CI]: −0.0 [−0.1 to 0.0], P = 0.329).

Conclusion

Preoperative immersive virtual reality tour of the operating theater did not reduce the incidence and severity of emergence delirium, although it was effective in alleviating preoperative anxiety in children.
What are the validity and reliability of the modified Yale Preoperative Anxiety Scale‐Short Form in children less than 2 years old?
Authors: Kühlmann Anne Y.R. , Lahdo Nisson , Staals Lonneke M. , van Dijk Monique
Published: October 2018

Background

Accurate measurement of preoperative anxiety is important for pediatric surgical patients’ care as well as for monitoring anxiety‐reducing interventions. The modified Yale Preoperative Anxiety Scale‐short form is well validated for this purpose in children aged 2 years and above, but not in younger children.

Aims

We aimed to validate the Dutch version of the modified Yale Preoperative Anxiety Scale‐short form for measuring preoperative anxiety in children less than 2 years old.

Methods

Two investigators independently assessed infants’ anxiety at the holding area and during induction of anesthesia with the modified Yale Preoperative Anxiety Scale‐short form and the COMFORT‐Behavior scale—live and from video observations. Construct validity and responsiveness of both scales were tested with Pearson correlation coefficient. Internal consistency of the modified Yale Preoperative Anxiety Scale‐short form was assessed using Cronbach's α, and inter‐rater reliability and intra‐rater reliability were tested using the intraclass correlation coefficient and Cohen's linearly weighted kappa. Hypotheses for sufficient inter‐rater reliability (r > 0.60) and validity (r > 0.65) had been formulated a priori in line with the COSMIN guidelines.

Results

Behavior of 129 infants (89.1% male) with a median age of 6.5 months (range 0.9‐16.5 months) was observed. The correlations between the modified Yale Preoperative Anxiety Scale‐short form and COMFORT‐Behavioral scale were strong at the holding area and at induction of anesthesia, as were the correlation of change scores between the holding area and induction. Internal consistency of the modified Yale Preoperative Anxiety Scale‐short form was excellent at both the holding area and at induction of anesthesia. Inter‐rater reliability was good to excellent on scale level and moderate to good on item level.

Conclusion

These findings support the validity and reliability of the Dutch version of the modified Yale Preoperative Anxiety Scale‐short form in children less than 2‐years‐old.
Senescence in growth and reproductive allocation in a bunchgrass
Authors: Li C. , Li H. , Yang Y.
Published: October 2018

Senescence is a puzzling phenomenon. Few convincing studies of senescence in perennial herbaceous plants exist. While ramets are known to senesce, whether senescence of bunchgrasses actually occurs is not clear.

In this study, we grew a set of plants of Elymus excelsus, a bunchgrass, to examine plant size, sexual reproduction and bud formation in individual plants in relation to their gradual ageing, in order to determine whether E. excelsus experiences senescence. We collected data in two consecutive years (2009 and 2010) from field samples of plants from 1 to 5 years old. Using regression models, we performed age‐related analyses of growth and reproduction parameters.

Our results showed that individual plant size (diameter, individual biomass), total biomass of ramets, number and biomass of reproductive ramets, percentage of ramets that were reproductive, reproductive allocation, over‐wintering buds and juvenile ramets all declined with age. However, vegetative growth (number and biomass of vegetative ramets) did not decrease with age.

Those plants that survived, dwindled in size as they aged. However, no plants shifted their resource allocation between growth and reproduction as they aged, so the shift in allocation did not account for the fall in size.
Proximity to a Traditional Physical Store: The Effects of Mitigating Online Disutility Costs
Authors: Nault Barrie R. , Rahman Mohammad S.
Published: October 2018

We examine the implications of proximity to a physical store in offline–online retail competition where online disutility costs, which encompasses factors such as trust in the seller, returns, and after‐sales support, are important. Building on classical models, we consider a traditional retailer's expansion online, benefitting from the physical store's presence in serving customers online. Our innovation is to allow online disutility costs to be mitigated if the purchase is from a dual‐channel retailer, defining the mitigation as a function of proximity to the traditional store. Although expansion online is rarely profitable for traditional retailers, the expanded presence increases consumer welfare—which is further increased by competition from a pure e‐tailer. However, the competition between a pure e‐tailer and dual‐channel retailers can lower social welfare: in aggregate consumers may incur greater online disutility costs than transportation costs to obtain lower prices online. When online disutility costs are high and no pure e‐tailer is present, dual‐channel retailer prices and profits, in traditional stores and online, are greater than those where the market only has physical stores and a pure e‐tailer. Furthermore, consumer welfare is lower. Thus, consumers benefit from an expanded presence of traditional retailers online only when online disutility costs are low enough that mitigation matters. If online disutility costs are low, then their mitigation can result in higher social welfare in a market with only dual‐channel retailers. Similarly, the mitigation of online disutility costs can result in higher social welfare when dual‐channel retailers and a pure e‐tailer coexist.
Solidarity Not Homogeneity: Constructing a Superordinate Aboriginal Identity That Protects Subgroup Identities
Authors: Neufeld Scott D. , Schmitt Michael T.
Published: October 2018

Superordinate identities formed around shared oppression provide political and psychological resources for marginalized groups. However, superordinate identities can also threaten the identities of the subgroups they attempt to bring together. We examined how a superordinate identity was constructed to protect subgroup identities using data from 31 urban Aboriginal participants who strongly identified with both their subgroup (heritage cultures) and superordinate Aboriginal identities. Participants defined the superordinate Aboriginal identity as a fundamentally diverse category where no one subgroup was more representative of the wider category than others. Participants also put their respect for subgroup diversity into practice by regularly engaging with Aboriginal (subgroup) cultures other than their own. Finally, participants felt that representations of the superordinate Aboriginal category should prioritize local cultures. We discuss these findings in relation to research in social psychology on superordinate and subgroup identities, multiculturalism, and collective resistance and provide some suggestions for how this work may be extended.
Exposure at Default Without Conversion Factors—Evidence from Global Credit Data for Large Corporate Revolving Facilities
Authors: Thackham Mark , Ma Jun
Published: October 2018

Credit granting institutions are in the business of lending money to customers, some of whom subsequently fail to repay as promised. For these events, accurate loan balance estimates—termed exposure at default (EAD)—provide quantification of potential losses and form a required input to minimum credit capital calculation under the Basel II Accord. Most available EAD research estimates the credit conversion factor (CCF), which is a transform of EAD, but as we highlight this has substantial deficiencies: an inherent singularity rendering the CCF undefined or numerically unstable and it often provides EAD estimates that fail economic intuition. We build a descriptive model for EAD—without relying on the CCF—using the Global Credit Data database, advancing the literature in three important ways. First we identify, like other studies on revolving facilities, that balance and limits drive EAD and we therefore develop our model to capture these joint dynamics flexibly. Second we find evidence in the data of risk-based line management where lenders tend to decrease limits for riskier obligors. Third we confirm results from other studies of mild EAD countercyclicality, whereby EAD is lower during a subdued economy.
An Imputation–Regularized Optimization Algorithm for High Dimensional Missing Data Problems and Beyond
Authors: Liang Faming , Jia Bochao , Xue Jingnan , Li Qizhai , Luo Ye
Published: October 2018

Missing data are frequently encountered in high dimensional problems, but they are usually difficult to deal with by using standard algorithms, such as the expectation–maximization algorithm and its variants. To tackle this difficulty, some problem-specific algorithms have been developed in the literature, but there still lacks a general algorithm. This work is to fill the gap: we propose a general algorithm for high dimensional missing data problems. The algorithm works by iterating between an imputation step and a regularized optimization step. At the imputation step, the missing data are imputed conditionally on the observed data and the current estimates of parameters and, at the regularized optimization step, a consistent estimate is found via the regularization approach for the minimizer of a Kullback–Leibler divergence defined on the pseudocomplete data. For high dimensional problems, the consistent estimate can be found under sparsity constraints. The consistency of the averaged estimate for the true parameter can be established under quite general conditions. The algorithm is illustrated by using high dimensional Gaussian graphical models, high dimensional variable selection and a random-coefficient model.
What Are Good‐Looking Candidates, and Can They Sway Election Results?*
Authors: Praino Rodrigo , Stockemer Daniel
Published: October 2018

Objective

In this article, we address two major gaps in the understanding of the relationship between candidate attractiveness and electoral success. With the assistance of the Victoria Police Criminal Identification Unit in Melbourne, Australia, we show how good‐looking candidates look like by building the faces of six “ideal candidates” in terms of physical attractiveness. Utilizing our “ideal candidates,” we then investigate whether candidate attractiveness can actually sway electoral results.

Methods

We proceed in four distinct steps, using data from the 2008 U.S. House of Representatives elections. First, we collect data on candidate attractiveness. Second, we build our “ideal candidates” and obtain their attractiveness ranking. Third, we model the effect of candidate attractiveness on candidate vote margins. Fourth, we run four hypothetical scenarios that assess whether candidate attractiveness can sway the electoral results in marginal seats.

Results

About two‐thirds of marginal races would trigger a different winner if the actual loser looked like our ideal candidates. In addition, virtually every single marginal race would have had a different outcome if the unsuccessful candidate looked like our “ideal candidate” and the successful candidate was very unattractive.

Conclusion

Candidate attractiveness can sway electoral results, provided that elections are competitive.
Highly specialized Cretaceous beetle parasitoids (Ripiphoridae) identified with optimized visualization of microstructures
Authors: Batelka Jan , Prokop Jakub , Pohl Hans , Bai Ming , Zhang Weiwei , Beutel Rolf G.
Published: October 2018

Extremely miniaturized longipedes insects (body length c. 0.3 mm) embedded in two pieces of Cretaceous amber from Myanmar are described and interpreted. Using inverted fluorescence and light microscopy for detailed analysis of microstructures, the inclusions were identified as primary larvae of the beetle family Ripiphoridae, subfamily Ripidiinae. While the structure of thoracic and abdominal segments including appendages corresponds well with the groundplan known in recent members of Ripidiinae, a curved prosternal ridge with prominent spines (each c. 5 μm), the reduced condition of stemmata and antennae and the lack of sharp mandibles are unique features within the entire family, apparently apomorphies of the longipedes larvae. A sinuate prosternal edge with a dense row of spines (prosternoctenidium) might be homologous with ‘head ctenidia’ in some previously described miniaturized conicocephalate larvae, but further investigation is needed. The morphological differences between the head of longipedes larvae and extant Ripidiinae are interpreted as adaptations to different groups of hosts and life strategies. Palaeoethology of the longipedes larvae is briefly discussed. In addition, the systematic placement of conicocephalate larvae from Canadian, Myanmar and Russian Cretaceous ambers, already interpreted by various authors as primary instars within Coleopterida (assigned to either Strepsiptera or to the coleopteran Tenebrionoidea: Ripiphoridae), is discussed.
Magnitude and pattern of improvement in processes of care for hospitalised children with diarrhoea and dehydration in Kenyan hospitals participating in a clinical network
Authors: Akech Samuel , Ayieko Phillip , Irimu Grace , Stepniewska Kasia , English Mike ,   Clinical Information Network authors
Published: October 2018

Objective

WHO recommends optimisation of available interventions to reduce deaths of under‐five children with diarrhoea and dehydration (DD). Clinical networks may help improve practice across many hospitals but experience with such networks is scarce. We describe magnitude and patterns of changes in processes of care for children with DD over the first 3 years of a clinical network.

Methods

Observational study involving children aged 2–59 months with DD admitted to 13 hospitals participating in the clinical network. Processes of individual patient care including agreement of assessment, diagnosis and treatment according to WHO guidelines were combined using the composite Paediatric Admission Quality of Care (PAQC) score (range 0–6).

Results

Data from 7657 children were analysed and improvements in PAQC scores were observed. Predicted mean PAQC score for all the hospitals at enrolment was 59.8% (95% CI: 54.7, 64.9) but showed a wide variation (variance 10.7%, 95% CI: 5.8, 19.6). Overall mean PAQC score increased by 13.8% (95% CI: 8.7–18.9, SD between hospitals: ±8.2) in the first 12 months, with an average 0.9% (95% CI: 0.3–1.5, SD ± 1.0) increase per month and plateaued thereafter, and changes were similar in two groups of hospitals joining the network at different times.

Conclusion

Adherence to guidelines for children admitted with DD can be improved through participation in a clinical network but improvement is limited, not uniform for all aspects of care and contexts and occurs early. Future research should address these issues.
Surgical ligation of patent ductus arteriosus in a dorper sheep
Authors: Halleran Jennifer L. , Baumwart Ryan D. , Dugat Danielle R. , Streeter Robert N. , Phillips Heidi
Published: October 2018

Objective

To report the diagnosis and treatment of a companion dorper wether with patent ductus arteriosus (PDA).

Study design

Case report.

Animal

An 8‐month‐old dorper wether presented to its primary care veterinarian for a persistent cough and was referred for suspected heart failure on the basis of physical examination and thoracic radiography. A PDA was diagnosed on echocardiography.

Methods

The sheep underwent cardiac catheterization and angiogram to measure pulmonary arterial and right ventricular (RV) pressures, identify the morphology of the PDA, and determine whether an intravascular occlusion of the PDA was feasible. Pulmonary artery pressure was 84/53 mm Hg (mean = 66), and RV pressures were 79/5 mm Hg (mean = 45); these were consistent with pulmonary hypertension. The size and shape of the PDA precluded vascular occlusion. Instead, the PDA was ligate through a left fourth intercostal approach.

Results

The sheep improved clinically after surgery. The PDA seemed closed on echocardiogram 3 days after surgery. Measurement of postoperative fractional shortening was consistent with decreased left ventricular systolic function that had resolved according to follow‐up echocardiography.

Conclusion

We report the first known diagnostic evaluation and successful treatment of naturally occurring PDA in a companion sheep.

Clinical significance

For economically valuable small ruminants, radiographs, echocardiography and cardiac catheterization can be used to diagnose and plan surgical treatment of PDAs, with a potential for a good long‐term outcome.
Evaluation of peer teaching and deliberate practice to teach veterinary surgery
Authors: Compton Nashua J. , Cary Julie A. , Wenz John R. , Lutter John D. , Mitchell Colin F. , Godfrey Jennifer
Published: October 2018

Objective

To assess the impact of peer teaching and deliberate practice on surgical skills acquisition and retention in first‐ and second‐year veterinary students.

Study design

Randomized, prospective, comparative study.

Sample population

Eighteen first‐year and 25 second‐year students from 1 college of veterinary medicine who had previously demonstrated proficiency in basic surgical skills.

Methods

Forty‐three participants were divided into 3 groups: the test group (group A, n = 15), who participated in a structured peer‐assisted learning program using deliberate practice; the time‐practice control group (group B, n = 15), who participated in an unstructured peer‐supported environment; and the assessment‐only control group (group C, n = 13), who participated in the assessments. Participants performed a subcutaneous mass removal on a cadaver model and were assessed via a global rating system. Three assessment points were evaluated: pretraining, immediate posttraining, and retention.

Results

The number of participants who achieved acceptable or excellent grand total scores in group A increased after training. Among all participants, 22% in group A, 35% in group B, and 38% in group C did not achieve an acceptable total score at the retention assessment.

Conclusion

The study population improved in skill level and retention through the use of standardized video and peer instruction with attention to effective learning strategies, particularly deliberate practice.

Clinical significance

Use and enhancement of the format introduced in this study could augment veterinary surgical education.
Renal dysfunction aggravated impaired cutaneous wound healing in diabetic mice
Authors: Xie Ping , Young Mimi Wu , Bian Huining , Niknam‐Bienia Solmaz , Hong Seok , Mustoe Thomas A , Galiano Robert D
Published: October 2018

Renal dysfunction has been associated with poor outcomes of wound healing in the diabetic population. The purpose of this study was to create an excisional wound healing model in diabetic mice with renal dysfunction to investigate the combined effects of diabetes and nephropathy on cutaneous ulcers. Renal impairment was introduced in diabetic db/db mice through unilateral nephrectomy and electrocoagulation of the contralateral kidney. Renal function was subsequently monitored with assays of blood urea nitrogen and spot urinary protein/creatinine ratio. After 8 weeks, splinted, full‐thickness excisional wounds were created on the dorsal skin and harvested on postoperative days 7 and 14 for further evaluation of wound healing. Renal injury promoted the increase of blood urea nitrogen 3 weeks after initial operation, which was maintained at double the control level throughout the study, concomitantly leading to a significant increase of spot urinary protein excretion. Diabetic mice with renal injury displayed notably impaired wound healing processes, concurrent with reductions in cellular proliferation and angiogenesis, as well as increases in M1 polarized macrophages, infiltrated neutrophils, oxidative stress, and cellular apoptosis. Furthermore, quantitative polymerase chain reaction (qPCR) results displayed corresponding changes of related genes (TNF‐α, IL‐1β, SOD2) in the wounds of renal injured db/db mice. Renal manipulation in this study accelerated the progress of renal impairment, which was demonstrated to aggravate impaired cutaneous wound healing in diabetic mice.
The humanistic and economic burden of chronic wounds: A systematic review
Authors: Olsson Maja , Järbrink Krister , Divakar Ushashree , Bajpai Ram , Upton Zee , Schmidtchen Artur , Car Josip
Published: October 2018

Chronic wounds are a health problem that have devastating consequences for patients and contribute major costs to healthcare systems and societies. To understand the magnitude of this health issue, a systematic review was undertaken. Searches were conducted in MEDLINE, EMBASE, EBM Reviews and Cochrane library, CINAHL, EBSCO, PsycINFO, and Global Health databases for articles published between 2000 and 2015. Included publications had to target adults (≥18 years of age), state wound chronicity (≥3 weeks) and/or label the wounds as chronic, complex, hard‐to‐heal, or having led to an amputation. The review excluded studies that did not present data on generic health‐related quality of life and/or cost data, case studies, randomized controlled trials, economic modeling studies, abstracts, and editorials. Extracted data were summarized into a narrative synthesis, and for a few articles using the same health‐related quality of life instrument, average estimates with 95% confidence intervals were calculated. Thirty articles met the inclusion criteria. Findings revealed that health‐related quality of life was lowest for physical pathologies, and based on average estimates were scores most inferior in the domain physical role for both patients with chronic wounds and for those with wound‐related amputations. The cost burden was mainly attributed to amputations for patients also comorbid with diabetes, where the cost for hospitalization ranged from US$12,851 to US$16,267 (median) for this patient group. Patients with chronic wounds have poor health‐related quality of life in general and wound‐related costs are substantial. Development and implementation of wound management strategies that focus on increasing health‐related quality of life and effectively reduce costs for this patient group are urgently needed.
Characterization and regulation of wild‐type and mutant TASK‐1 two pore domain potassium channels indicated in pulmonary arterial hypertension
Authors: Cunningham Kevin P. , Holden Robyn G. , Escribano‐Subias Pilar M. , Cogolludo Angel , Veale Emma L. , Mathie Alistair
Published: October 2018

Key points

The TASK‐1 channel gene (KCNK3) has been identified as a possible disease‐causing gene in heritable pulmonary arterial hypertension (PAH).

In the present study, we show that novel mutated TASK‐1 channels, seen in PAH patients, have a substantially reduced current compared to wild‐type TASK‐1 channels.

These mutated TASK‐1 channels are located at the plasma membrane to the same degree as wild‐type TASK‐1 channels.

ONO‐RS‐082 and alkaline pH 8.4 both activate TASK‐1 channels but do not recover current through mutant TASK‐1 channels.

We show that the guanylate cyclase activator, riociguat, a novel treatment for PAH, enhances current through TASK‐1 channels but does not recover current through mutant TASK‐1 channels.

Pulmonary arterial hypertension (PAH) affects ∼15–50 people per million. KCNK3, the gene that encodes the two pore domain potassium channel TASK‐1 (K2P3.1), has been identified as a possible disease‐causing gene in heritable PAH. Recently, two new mutations have been identified in KCNK3 in PAH patients: G106R and L214R. The present study aimed to characterize the functional properties and regulation of wild‐type (WT) and mutated TASK‐1 channels and determine how these might contribute to PAH and its treatment. Currents through WT and mutated human TASK‐1 channels transiently expressed in tsA201 cells were measured using whole‐cell patch clamp electrophysiology. Localization of fluorescence‐tagged channels was visualized using confocal microscopy and quantified with in‐cell and on‐cell westerns. G106R or L214R mutated channels were located at the plasma membrane to the same degree as WT channels; however, their current was markedly reduced compared to WT TASK‐1 channels. Functional current through these mutated channels could not be restored using activators of WT TASK‐1 channels (pH 8.4, ONO‐RS‐082). The guanylate cyclase activator, riociguat, enhanced current through WT TASK‐1 channels; however, similar to the other activators investigated, riociguat did not have any effect on current through mutated TASK‐1 channels. Thus, novel mutations in TASK‐1 seen in PAH substantially alter the functional properties of these channels. Current through these channels could not be restored by activators of TASK‐1 channels. Riociguat enhancement of current through TASK‐1 channels could contribute to its therapeutic benefit in the treatment of PAH.
Comparison of the Socioeconomic Factors and Diagnostic Test between Pulmonary Tuberculosis (PTB) and Extrapulmonary Tuberculosis (ETB) in Boyacá (Colombia), in 2015
Authors: Méndez Fanidño Yardany Rafael , Caicedo Ochoa Edgar Yaset , Urrutia Gómez Jorge Andrés , Cortés Motta Héctor Fabio , Ávila Espitia Nasly Consuelo , Álvarez Gallego Gloria Camila
Published: October 2018

Introduction: Tuberculosis (TB) is an infectious disease caused by Micobacterium tuberculosis. It usually affects the lungs, but can also affect other systems. The objective of this study was to make a comparison of the socioeconomic factors and diagnostic test between pulmonary tuberculosis (PTB) and extrapulmonary tuberculosis (ETB) in Boyacá (Colombia) in 2015. Methods: A retrospective analytical observational study was conducted on the data provided by the Boyacá Department of Health about the TB possible cases reported in the SIVIGILA system. 103 TB possible cases were selected, then these cases were divided in accordance with the TB type in two groups, PTB and ETB. Duplicated data were excluded. Results: The highest number of isolates was of PTB. With regard to the ETB group, they required more medical attention, and the most frequent isolates were meningeal, pleural and osteoarticular. In addition, undernourishment was related with PTB. Conclusion: The creation of new social, cultural and economic approaches against the TB dissemination becomes a primary point for the control of this disease.
Creep Strength Evaluation of a New and a Used Grade 91 Welded Joints by Using a Miniature Specimen
Authors: Ogata Takashi
Published: October 2018

Grade 91 is widely used for steam pipes and tubes in high temperature boilers of ultra-super critical power plants in Japan. It was reported that creep damage may initiate at the fine grain region within the heat affected zone (HAZ) in welded joints prior to the base metal, so called “Type IV” damage, which causes steam leakage in existing power plants. Therefore, development of creep damage assessment methods is not only an important but also an urgent subject to maintain operation reliability. In order to evaluate creep damage of welded joints based on finite element analyses, creep deformation properties of a base metal, a weld metal and a HAZ have to be obtained from creep tests. However, it is difficult to cut a standard size creep specimen from the HAZ region. Only a miniature size specimen is available from the narrow HAZ region. Therefore, development of creep testing and evaluation technique for miniature size specimens is highly expected. In this study, a miniature tensile type solid bar specimen with 1mm diameter was machined from a base metal, a weld metal and a HAZ of a new and a used Grade 91 welded joints, and creep tests of these miniature specimens were conducted by using a special developed creep testing machine. It was found that creep deformation property is almost identical between the base metal and weld metal, and creep strain rate of the HAZ is much faster than that of these metals in the new welded joint. Relationships between stress and creep strain rates of the base metal and the HAZ in the used welded joint are within scatter bands of those in the new material. On the other hand, creep strain rate of the weld metal in the used welded joint became much faster than that in the new one. Then both the standard size and the miniature size cross weld specimens were machined from the new and the used welded joints and were tested under the same temperature and stress conditions. Rupture time of the miniature cross weld specimen is much shorter than that of the standard size cross weld specimen. The finite element creep analysis of the specimens indicates that higher triaxiality stress yields within the HAZ of the standard size specimen than that of the miniature specimen causing faster creep strain rate in the HAZ of the miniature cross weld specimen.
Bearing Friction Torque in Threaded Fasteners With Non-Flat Underhead Contact
Authors: Nassar Sayed A. , Gerini Romagnoli Marco , Lee Joon Ha
Published: October 2018

This study provides experimentally validated formulation of underhead bearing friction torque component during tightening of threaded fasteners with non-flat contact with the joint. Motosh model is utilized for spherical and conical contact surfaces for various scenarios of contact pressure. For each pressure scenario, a single non-dimensional 3-D graph is generated for the corresponding values of an effective bearing friction radius. A rotating sliding speed-dependent friction coefficient model is also investigated for its impact of the results of bearing friction radius. Torque-Tension testing is used to measure the bearing friction torque and the corresponding bearing friction coefficients using Motosh model, in which the newly formulated bearing friction radius expressions are entered. Obtained bearing friction coefficient values are then compared with those published by the threaded fastener manufacturer.
INCEFA-PLUS: Increasing Safety in NPPs by Covering Gaps in Environmental Fatigue Assessment
Authors: Mottershead Kevin , Bruchhausen Matthias , Cuvilliez Sam , Cicero Sergio
Published: October 2018

INCEFA-PLUS is a five-year project supported by the European Commission HORIZON 2020 programme. The project commenced in mid-2015. Sixteen organisations from across Europe have combined forces to deliver new experimental data which will support the development of improved guidelines for assessment of environmental fatigue damage to ensure safe operation of nuclear power plants. Within INCEFA-PLUS, the effects of mean strain and stress, hold time, strain amplitude and surface finish on fatigue endurance of austenitic stainless steels in light water reactor environments are being studied experimentally, these being issues of common interest to all participants. The data obtained is being collected and standardised in an online environmental fatigue database, implemented with the assistance of an INCEFA-PLUS led CEN (European Committee for Standardization) workshop on this aspect. Later in the project it is planned that INCEFA-PLUS will develop and disseminate methods for including the new data into assessment approaches for environmental fatigue degradation.

This paper provides an overall update to project developments since it was last presented at PVP2017 [[1]]. As well as being a standalone paper, the paper will also serve as an introduction to more detailed papers also being submitted covering 4 specific aspects of the project. In particular, this paper summarises:

• The results for Phase 1 testing.

• The agreed plans for Phase 2 testing

• A summary of emerging sensitivities to, and inter-dependencies between:

○ Mean strain and stress, surface finish, strain amplitude and hold time.

○ Environment

○ Material

○ Laboratory

• Latest thinking on direction for the project in its last two years.

• The latest thoughts on how the project results will be used to advance development of improved assessment guidelines.

• A summary of dissemination achieved and planned for the forthcoming year.
Combined Statistical-Mechanical Characterization of a Next Generation Textured PTFE for Extreme Environments
Authors: Shinde Sannmit , Gordon Ali P. , Poust Zachary , Pitolaj Steve , Drago Jim , Nichols Paul
Published: October 2018

Pressurized vessels that transfer media from one location to another often contain a bolted connection. Gaskets are essential for these systems since they confer high levels of leak mitigation across of range of operating environments (i.e., internal pressure and temperature). The balance of both sealability and compressibility must be displayed in candidate gasket materials to be subjected to aggressive operating conditions. Historically, thin gauge gasket (i.e., 1/16” thick) confer high sealability while thick gaskets offer superior compressibility (i.e., 1/8”). Fabricated with skive cut, ceramic particle-reinforced PTFE, these materials display linear viscoelastic behavior that allow consolidation to occur. For example, GYLON® 3504 is filled with Aluminosilicate Microspheres, GYLON®3510 is filled with barium sulfate, respectively, to efficiently fill crevices along the surfaces of the flange. Novel textured PTFE gasket (3504 EPX and 3510 EPX) have been developed to simultaneously confer sealability and compressibility compared to flat products. A design of experiments (DoE) approach is applied to characterize the factors that influence load relaxation responses of the both candidate textured PTFE (dual-face honeycomb) and existing (flat) gasket styles. Using an instrumented test platform analyzed. A new parameter is presented to quantify gasket efficiency. The collection of efficiency measurement methods and approach to re-torque optimization convey a novel framework that designers can invoke to facilitate improved flange performance.
A Perspective of the Small Punch Test Application to the Evaluation of Hydrogen Embrittlement in Steels: Effect of Punch Rate on Fracture Properties
Authors: Arroyo B. , Álvarez J. A. , Gutiérrez-Solana F. , Sainz J. , Lacalle R.
Published: October 2018

In this paper, different techniques to test notched Small Punch (SPT) samples for the estimation of the fracture properties in aggressive environments are studied, based on the comparison of the micromechanisms at different rates.

Pre-embrittled samples subsequently tested in air at conventional rates (0.01 and 0.002 mm/s) are compared to embrittled ones tested in environment at the same rates (0.01 and 0.002 mm/s) and at a very slow rate (5E−5 mm/s); a set of samples tested in environment under static loads that produce very slow rates complete the experimental results. To close the study, numerical simulations based on obtaining a punch rate that produces an equivalent CTOD growing rate in the edge of the notch to the one at the crack tip of a C(T) specimen for a given solicitation rate is carried out.

As a conclusion, is recommended to test SPT notched specimens in environment at very slow rates, of arround E−6 mm/s, when characterizing in Hydrogen Embrittlement (HE) scenarios, in order to allow the interaction material-environment to govern the process.
A Study of the Material Properties and Performance of Hot Isostatically Pressed (HIP) Type 316L Stainless Steel Powders and HIP Processing Available From Today’s International Supply Chain
Authors: Kyffin William , Gandy David , Burdett Barry
Published: October 2018

Hot Isostatic Pressing (HIP) of type 316L austenitic stainless steel powder has been an established manufacturing practice for more than twenty five years within the oil and gas sectors and more recently in the naval defence industry. The successful ASME Code Case approval (N-834) has facilitated the manufacture of 316L components via Powder Metallurgy HIP (PM/HIP) for the civil nuclear sector. However, a number of issues have tended to hinder the uptake of PM/HIP as an alternative viable manufacturing route for both castings and forgings.

Firstly, the powder specification for 316L and HIP processing parameters has typically been left to the discretion of the manufacturers. As such, the finer details of HIP product specification require greater clarity and definition for optimum performance/reproducibility. Secondly, comparison of historical data for 316L PM/HIP has shown variation in the Charpy impact toughness performance. These differences have been attributed to the oxygen content of the atomised powder, with greater oxygen contents yielding product with reduced impact properties.

Based on these factors, a systematic study of the current state of the art of 316L commercial powder production, encapsulation/consolidation and selected HIP parameters was undertaken in collaboration with the Electric Power Research Institute (EPRI). A 316L powder specification was developed that primarily limited the oxygen content of the powder to under 130ppm. This lower oxygen limit reflects the improvements that commercial powder suppliers have been making over the past decade to ensure greater powder cleanliness.

The test programme generated a significant body of test data based on 3 × 3 × 3 matrix of: powder supply, HIP service provider and HIP sustain times. The results were excellent across the full range of variables studied with all test billets passing the specification requirements of ASTM A988 and additional imposed requirements.

Very consistent 316L material properties were produced for billets manufactured via differing HIP service providers across the comprehensive destructive test programme. This demonstrates the robustness and uniformity of the PM/HIP supply chain in producing 316L material of the requisite quality. In addition, no significant difference in material properties was noted for material pressed between 2–8 hours hold time, suggesting that the HIP process window is large with respect to hold time.

Of significant note was that material produced with one powder yielded material with consistently the highest strengths and Charpy impact toughness. This has been attributed to chemical composition of the powder, which featured both a low oxygen and also a high nitrogen content.
Ensuring Data Quality for Environmental Fatigue: INCEFA-PLUS Testing Procedure and Data Evaluation
Authors: Vankeerberghen Marc , Bruchhausen Matthias , Cicero Román , Doremus Luc , Le-Roux Jean-Christophe , Platts Norman , Spätig Philippe , Twite Marius , Mottershead Kevin
Published: October 2018

INCEFA-PLUS stands for INcreasing safety in nuclear power plants by Covering gaps in Environmental Fatigue Assessment. It is a five year project supported by the European Commission HORIZON2020 program that commenced in mid-2015 and in which sixteen organizations from across Europe participate. Specifically, the effects of mean strain/stress, hold time, strain amplitude and surface finish on fatigue life of austenitic stainless steels in light water reactor environments are being studied, these being issues of common interest to all participants.

The project will develop proposals for improvements to methods for environmental fatigue assessment of nuclear plant components. Therefore, extensive testing capacity is being solicited in various laboratories across Europe in order to add to the existing amount of published data on environmentally assisted fatigue.

Since there currently is no standard on environmental fatigue testing, it was imperative to come up with and agree upon a testing procedure within the consortium to minimize lab-to-lab variations in test results. This was done prior to the first phase of testing, but an update of the procedure was required after review of initial results, when additional potential lab-to-lab differences were identified. The current status of the so-called test protocol, and the key areas of difference found between different testing facilities, will be discussed.

Due to the large test matrix within INCEFA-PLUS, distributed amongst various test laboratories, it has been necessary to develop a method to assign a data quality level to each test result, and a minimum data quality requirement for results that will be included in the project’s datasets used for analysis. Furthermore, the project has triggered international interest in facilitating mutual data access, and this requires data is gathered in a common database with data quality ratings applied. Ways to address the evaluation of data quality will be discussed.

In a way, both activities, on a test protocol and on data review, jointly contribute to data quality by, respectively, ensuring a pre-test, common test procedure and a post-test, harmonized data evaluation.

The large number of participants in the INCEFA-PLUS project presents a unique opportunity to gain consensus on light water reactor environment fatigue testing procedures and data quality assessment from experts working in a range of different organizations. The test protocol and data quality ratings developed within the INCEFA-PLUS project could be adopted by other organizations, or possibly used as the basis for future testing standards documents to harmonize approaches across the nuclear industry.
The Fracture Toughness Properties of China Manufactured Reactor Pressure Vessel Steels in Transition Temperature Range
Authors: Sun Kai , Wu Xiaoyong , Li Guoyun , Wen Bang
Published: October 2018

Over the past decade, many generation III pressurized water reactor power plants have been under construction in China. Most reactor pressure vessel steels for these plants construction are homemade. Historically, Charpy V-notch specimens are predominantly used to monitor the toughness of RPV steels. However, fracture toughness provides the quantitative predictions of the critical crack size and the allowable stress in structural integrity assessment. This paper evaluates the fracture toughness properties of China manufactured RPV steels directly measured in transition temperature range by using master curve method. Some specimens were irradiated in the High Flux Engineering Test Reactor. The influences of loading rate, test temperature, specimen configuration and neutron irradiation on T0 were also investigated. The experimental results show that China manufactured RPV steels exhibit good fracture toughness properties.
Methods of Material Testing in High-Pressure Hydrogen Environment and Evaluation of Hydrogen Compatibility of Metallic Materials: Current Status in Japan
Authors: Kobayashi Hideo , Kobayashi Hiroshi , Sano Takeru , Maeda Takashi , Tamura Hiroaki , Ishizuka Ayumu , Kimura Mitsuo , Yoshikawa Nobuhiro , Iijima Takashi , Yamabe Junichiro , Matsuoka Saburo , Matsunaga Hisao
Published: October 2018

In Japan, with regards to the widespread commercialization of 70 MPa-class hydrogen refueling stations and fuel cell vehicles, two national projects have been promoted on both the infrastructure and the automobile sides. These projects have been promoted to establish the criteria for determining hydrogen compatibility of materials and to expand the usable materials for high-pressure hydrogen environment. For these projects, establishing test methods to evaluate the hydrogen compatibility of materials is one of the most important tasks. This paper describes the status of common standardization of testing methods. Two projects share a common database for the testing results, which is currently put to practical use.
Recent Studies Towards Updating the BS7910 Flaw Interaction Rule
Authors: Bezensek Bostjan , Coules Harry E.
Published: October 2018

Fitness for service assessment procedures rely on flaw interaction rules for assessment of multiple flaws in close proximity. Such rules are aimed at avoiding excessive amplification of the crack driving force that may result in a non-conservative fracture assessment. In BS7910, the 2013 edition [1] introduced a new flaw interaction rule for the co-planar flaws where the proximity of adjacent flaws is judged based on flaw height (i.e. s = 0.5*max(a1,a2) for surface flaws). The rule was introduced for flaws with aspect ratio of a/c < 1 for both flaws, while for other flaw shapes and combinations the earlier rule from the predecessor document PD6493:1993 [2] was retained. This paper summarises the recent work done by the authors and work from literature to examine the applicability of the s = 0.5*max(a1,a2) rule to flaws with aspect ratio a/c ≥ 1 and dissimilar flaw combinations.

It is shown that the current BS7910 rule based on s = 0.5*max(a1,a2) produces a conservative flaw assessment with the use of BS7910 solutions for stress intensity factor and reference stress. An exception are cases of two deep surface flaws where the rule is proposed to change to:

s ≤ max(a1, a2) for two surface flaws with a1/t & a2/t > 0.5
Experimental Study of the Weld Residual Stress in Manually and Mechanically Fabricated Dissimilar Metal Weld
Authors: Duan Xinjian , Glover Andrew , Sun Dongmei , Paddea Sanjooram
Published: October 2018

The dissimilar metal welds between the Inconel 600 flow element and the SA-106 Grade B carbon pipe with Alloy 82 or Alloy 182 filler material of some CANDU® designs have been identified as being susceptible to Primary Water Stress Corrosion Cracking (PWSCC). Initiation and growth of PWSCC in a Dissimilar Metal Weld (DMW) are driven primarily by Welding Residual Stresses (WRS). The present paper focuses on the experimental study of weld residual stress distribution in manually and mechanically fabricated DMWs with emphasis on the effect of repair.

A series of DMW samples are firstly fabricated in accordance with the original welding procedures for those DMWs in the field, which were fabricated in 1970s and 1980s. Multiple thermocouples were used to record the temperature evolution during the entire welding process. These samples were then examined by ASME qualified personnel in accordance with the requirements for Class 1 weld in Article 9 of Section V of ASME BVPC using Visual Testing (VT) and Radiography Testing (RT). Repair was then performed in some samples, and further NDE examinations were performed. The qualified samples (with and without repair) were finally subject to destructive weld residual stress measurement using contour method.

It is observed that weld repair dramatically changes the distribution of weld residuals tress. The use of a constant through-thickness WRS of 60,000 psi (415 MPa) is justified as the bounding case.