bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Weld Residual Stresses on Ductile Crack Behavior in AISI Type 316LN Stainless Steel Weld Joint
Authors: Namburu Sai Deepak , Chebolu Lakshmana Rao , Subramanian A. Krishnan , Prakash Raghu , Gomathy Sasikala
Published: November 2018

Welding residual stress is one of the main concerns in the process of fabrication and operation because of failures in welded steel joints due to its potential effect on structural integrity. This work focuses on the effect of welding residual stress on the ductile crack growth behavior in AISI 316LN welded CT specimens. Two-dimensional plane strain model has been used to simulate the CT specimen. X-ray diffraction technique is used to obtain residual stress value at the SS 316LN weld joint. The GTN model has been employed to estimate the ductile crack growth behavior in the CT-specimen. Results show that residual stresses influence the ductile crack growth behavior. The effect of residual stress has also been investigated for cases with different initial void volume fraction, crack lengths.
A Non-Bolted Restraint for Coke Drums
Authors: Samman Mahmod , Kaye Alwyn
Published: November 2018

The failure of coke drum anchor bolts is a demanding and recurring maintenance item for many delayed coking operators. While there are several factors that can contribute to these failures, some studies have demonstrated that significant stresses may result from thermal expansion of the drum under non-uniform thermal gradients. To address bolt failures, a restraint system that utilizes non-contacting anchor blocks has been developed and implemented for the first time on a set of operating coke drums. In this paper, the background of anchor bolt failures as well as the design and first implementation of the new restraint system are discussed.
Dynamic Assessment of the Core Barrel During Loss of Coolant Accident
Authors: Dubyk Yaroslav , Filonov Vladislav , Ishchenko Oleksii , Orynyak Igor , Filonova Yuliia
Published: November 2018

This article focuses on the dynamic behavior of the Pressurized Water Reactor (PWR) during the Loss Of Coolant Accident (LOCA) which cause the significant acoustic loads on the Core Shrouds. The finite element analysis of a PWR was performed to obtain the acoustic response to the LOCA event. We have performed dynamic stress and strain calculations in the frequency domain for the Core Barrel, according to classical shell theories. The Duhamel integral was used to calculate the transient response of a shell to the transient load caused by the water hammer event. The results obtained were used for fracture mechanics evaluations for flaws, which may occur between inservice inspections.
Results and Correlations From Analyses of the ENSA ENUN 32P Cask Transport Tests
Authors: Kalinina Elena A. , Gordon Natalie , Ammerman Douglas J. , Uncapher William L. , Saltzstein Sylvia J. , Wright Catherine
Published: November 2018

An ENUN 32P cask supplied by Equipos Nucleares S.A. (ENSA) was transported 9,600 miles by road, sea, and rail in 2017 in order to collect shock and vibration data on the cask system and surrogate spent fuel assemblies within the cask.

The task of examining 101,857 ASCII data files — 6.002 terabytes of data (this includes binary and ASCII files) — has begun. Some results of preliminary analyses are presented in this paper.

A total of seventy-seven accelerometers and strain gauges were attached by Sandia National Laboratories (SNL) to three surrogate spent fuel assemblies, the cask basket, the cask body, the transport cradle, and the transport platforms. The assemblies were provided by SNL, Empresa Nacional de Residuos Radiactivos, S.A. (ENRESA), and a collaboration of Korean institutions. The cask system was first subjected to cask handling operations at the ENSA facility. The cask was then transported by heavy-haul truck in northern Spain and shipped from Spain to Belgium and subsequently to Baltimore on two roll-on/roll-off ships. From Baltimore, the cask was transported by rail using a 12-axle railcar to the American Association of Railroads’ Transportation Technology Center, Inc. (TTCI) near Pueblo, Colorado where a series of special rail tests were performed. Data were continuously collected during this entire sequence of multi-modal transportation events. (We did not collect data on the transfer between modes of transportation.)

Of particular interest — indeed the original motivation for these tests — are the strains measured on the zirconium-alloy tubes in the assemblies. The strains for each of the transport modes are compared to the yield strength of irradiated Zircaloy to illustrate the margin against rod failure during normal conditions of transport.

The accelerometer data provides essential comparisons of the accelerations on the different components of the cask system exhibiting both amplification and attenuation of the accelerations at the transport platforms through the cradle and cask and up to the interior of the cask. These data are essential for modeling cask systems.

This paper concentrates on analyses of the testing of the cask on a 12-axle railcar at TTCI.
Correlating Coke Drum Profiles With Observed Surface Damage
Authors: Araque Egler D. , Rutt Daryl K. , Love Darren R. , Park Stephen M. , Clark Rick D. , Dawson Jason J.
Published: November 2018

The frequency and extent of vessel bulging and cracking being registered in delayed coke drums throughout the global coking industry has accelerated significantly as refinery operators reduce their cycle times. Several theoretical approaches have been developed to identify how a bulged area may lead to drum damage; however, limited information has been presented to match the theoretical predictions with actual surface damage reported by coke drum operators.

The results of hundreds of laser scans spanning the last 25 years have been analyzed to correlate vessel bulging with observed surface damage. Specific categorizations of bulge profiles, and the proximity of these to circumferential weld seams (circs), have been calibrated against hundreds of real-world examples of drum damage and failure, including through wall cracking and stress cracking of the cladding, and further associated with the triggers for repair strategies implemented by industry leading refiners.

Strong correlations between specific aspects of bulge profiles and the presence of surface damage were found resulting in an assessment tool that can rank and prioritize coke drum distortions on the likelihood of damage, and can serve as a useful guide for planning future coke drum maintenance.
Effect of Steam Hammer Pressure Wave Steepening on Pipe Supports
Authors: Mayes Alex , Gawande Kshitij P.
Published: November 2018

Safety valve closure is employed within power plant piping systems to protect sensitive components from damage due to irregular events causing abrupt pressure variations of the thermal fluid flow. The valve closure creates a sudden obstruction to the flow, generating a pressure wave within the fluid which travels upstream and impacts at the pipe elbows. Such an event is known as steam hammer. This steam hammer pressure wave is capable of producing significant loads and stresses which can disrupt the piping supports as the wave travels throughout the pipe system. Previous studies have shown that the magnitude of these transient loads depend upon the characteristics of the flow, valve closure time, elbow-to-elbow pipe section lengths, the piping system flexibility, and the ‘steepness’ of the pressure transient. The latter effect has been ignored in most steam hammer studies; however, wave steepening has been shown to have a significant effect in cases where the pressure wave travels long distances from the safety valve. This study focuses on Computational Fluid Dynamics (CFD) modeling of rapid valve closure to produce this wave steepening effect and to investigate the significance in terms of transient pipe support loads.
Pipe Ovalization Prediction for the Pipe-Laying Ocean System
Authors: Bartecký Matěj , Halama Radim
Published: November 2018

This contribution brings a new insight into pipe cross section ovalisation due to plastic deformation during pipe-lying process to the seabed. Firstly, the influence of material model calibration on ovalization prediction is presented on pure bending case including the Prager model, the Chaboche model and the modified Abdel-Karim–Ohno model. The mechanism responsible for cross section ovalisation was identified as the phenomenon of the accumulation of plastic deformation, the so-called ratcheting. The next part of this contribution presents main results of the pipe-laying process simulation. The pipe cross-section behavior during passing the considered pipe-laying system is studied in detail. A macro based solution makes possible to do a parametric study and to easily apply the offshore standard DNV-OS-F101 in technical practice.
Proposed Methodology Changes to Determine Minimum Design Metal Temperature of ASME/API Impact Tested Materials Based on Fracture Mechanics
Authors: Kummari Seetha Ramudu , Macejko Brian , Prueter Phillip E.
Published: November 2018

For equipment designed to ASME or API standards, it is common practice to perform impact testing of base material and/or weldments to establish the Minimum Design Metal Temperature (MDMT). The impact test is typically a Charpy V-Notch (CVN) test and the test temperature is set equal to the MDMT. The required Charpy energy at MDMT can vary anywhere from 10 ft-lbs to 40 ft-lbs depending on material specification, thickness, and the ASME/API standard. The detailed historical background behind the Charpy energy requirements of different ASME/API standards is not well documented. Additionally, no credit is given for post weld heat treatment (PWHT) of impact tested materials. The CVN tests are used because they are quick and economical for quality control, but the tests only provide a relative indication of material toughness. Consequently, the current impact test requirements lead to inconsistent results in brittle fracture assessments, conducted through explicit fracture mechanics.

In this paper, two examples are presented to highlight the inconsistencies of the current impact test requirements. A methodology of estimating MDMT for impact tested materials based on fracture mechanics, consistent with Welding Research Council (WRC) Bulletin 562 [1] is also presented. Furthermore, this methodology explicitly accounts for the effects of PWHT (and the influence of weld residual stress on crack driving force) for impact tested materials. A methodology of adjusting MDMT for in-service impact tested materials is also presented. In the interest of moving towards harmonizing the impact test requirements, an alternative procedure for establishing impact test requirements is presented for ASME/API consideration.
A Study for Theoretical Modeling of Cavitation Inducement From the Solid-Fluid Interface With Fluid-Structure Interaction
Authors: Kojima Tomohisa , Inaba Kazuaki , Takada Yuto
Published: November 2018

A theoretical model was explored for predicting cavitation generation from a solid-fluid interface with fluid-structure interaction. Predicting cavitation generation is crucial to evaluate the lifetime of fluid machines. Cavitation has been generated from a solid-fluid interface with tensile stress (pressure) wave propagation across the interface. It was revealed that cavitation generation was suppressed when the surface wettability of the solid in a solid-fluid interface was improved (hydrophilized). It means that a condition exists in which cavitation is not generated despite the existence of bubble nuclei in water. This phenomenon cannot be explained by the conventional theory of fluid mechanics. In this study, an analogy between the theory of crack propagation in fracture mechanics and cavitation generation and propagation from a solid-fluid interface with fluid-structure interactions is developed and applied. An impact experiment was conducted with a free-falling projectile that hit a cylindrical solid buffer placed on top of a water surface within an elastic tube standing on the ground. The projectile impact created a stress wave propagating through the buffer and across the interface of the buffer and water. During the experiments, cavitation bubbles were generated from the interface of the buffer and water due to tensile wave propagation across the interface. Cavitation intensity was controlled by adding a surfactant to water. A bubble was set on the solid-fluid interface beforehand, then its growth with stress (or pressure) wave propagation was observed. The formularization of cavitation occurrence was tested by using initial crack length and stress in fracture mechanics as an analogy for the diameter of pre-set bubble and pressure wave amplitude.
The Fracture Limit of Steel-Frame Members Under Dynamic Repeated Loads Through the Shaking Table Test
Authors: Shiomi Kensuke , Wada Yusuke
Published: November 2018

Recently, much larger earthquakes are considered in the seismic designs of steel-frame structures in Japan. Under these severe ground motions, it is expected that not only the elasto-plastic deformation but also the fracture of the structural members could occur during the earthquakes. And through these situations, the more advanced seismic design or evaluation method which allow the partial destruction inside the structure and prevent from the worst-case scenario like the whole collapse are coming to be demanded. One of the ways to achieve this demand is considering the effects of not only the elasto-plastic deformation but also the fracture of structural members in the seismic analysis. In order for that, it is important to clarify the fracture limit of steel-frame members precisely under the dynamic load. Many static tests to clarify the members’ ultimate behavior were conducted in the past, but the dynamic tests were not well enough.

In this research, the vibration tests were conducted to clarify the fracture limit of steel-frame members under the dynamic load. The behavior of the steel-frame members until the fracture was obtained by applying the repeated dynamic bending deformation with the shaking table. Also, The FEM analysis for the shaking table test results was conducted. Through the tests and the analysis study which simulates the test results, the mechanism of the member fracture occurred in the test under the dynamic loads were examined.
Evaluating Large Aboveground Storage Tanks Subject to Seismic Loading: Part II — Explicit Dynamic Analysis With Liquid Sloshing Effects
Authors: Kummari Seetha Ramudu , Prueter Phillip E. , Bifano Michael F. P.
Published: November 2018

The dynamic response of storage tanks subjected to seismic loading is complex. Analyzing the structural response of a tank is not only dependent on accurately modeling the major design features and simulating the seismic loading, but also the sloshing of the fluid contained within the tank can affect the overall behavior and likely failure modes. Advanced dynamic simulation techniques, such as the ones discussed herein, permit comparison between these closed-form methods and computational predictions; that is, any potential conservatism or lack thereof associated with traditional design by rule methodologies can be identified using computational analysis. Additionally, for tanks that were not originally designed to a modern Code or recommended practice that includes consideration for seismic loading, the computational analysis methods discussed in this study offer a means to evaluate the structural integrity of vintage tanks under seismic loading conditions that are still in service today.

This paper discusses explicit dynamic finite element analysis (FEA) techniques to simulate seismic loading on a large, aboveground, in-service Ammonia storage tank that carries a high consequence of failure. The fluid-structure interaction and sloshing behavior of the contained fluid are directly accounted for. Commentary on using smooth particle hydrodynamics (SPH), coupled Eulerian-Lagrangian (CEL), and computational fluid dynamics (CFD) analysis techniques is provided. The underlying methodology behind these simulation techniques is discussed, and the overall dynamic response of the tank is investigated. The results from the explicit dynamic seismic simulations are compared with the current seismic design guidance provided in API 650 [1] and equivalent static simulation techniques (documented in Part I of this study [2]). Furthermore, this case study highlights a practical application where advanced analysis is employed to investigate a real-life fluid-structure interaction problem.
Temperature Jump Measurement at Stainless Steel and Helium Interface: Application to Used Nuclear Fuel Vacuum Drying Process
Authors: Zampella Cody , Hadj-Nacer Mustafa , Greiner Miles
Published: November 2018

Vacuum drying of nuclear fuel canisters may cause the temperature of fuel assemblies to considerably increase due to the effect of gas rarefaction at low pressures. This effect may induce a temperature-jump at the gas-solid interfaces. It is important to predict the temperature-jump at these interfaces to accurately estimate the maximum temperature of the fuel assemblies during vacuum drying.

The objective of this work is to setup a concentric cylinders experimental apparatus that can acquire data to benchmark rarefied gas heat transfer simulations, and determine the temperature-jump coefficient at the interface between stainless steel surface and helium gas. The temperature-jump is determined by measuring the temperature difference and heat flux across a 2-mm gap between the concentric cylinders that contains rarefied helium and compare the results to analytical calculations in the slip rarefaction regime.
Seismic Responses From Linear and Nonlinear Dynamic Analyis of RC Shear Walls
Authors: Kim Do Yeon
Published: November 2018

Seismic responses from linear and nonlinear dynamic analyses of reinforced concrete (RC) shear walls are compared to see how the damping ratio and cracking behavior affect the dynamic response of the RC structures used in the nuclear power plant. The nonlinear dynamic analyses are conducted based on the numerical model which is developed to simulate the nonlinear hysteretic behavior of RC structures subjected to in-plane shear. Through comparison of the obtained numerical results with experimental data such as load-displacement relationships and response time-histories, the developed numerical model is validated. The acceleration response spectra from the nonlinear dynamic analysis results of selected RC shear wall and those from linear dynamic analysis with combinations of the damping ratio and concrete stiffness considerations according to the level of earthquake loads and the resultant stresses are addressed.
Study on TMD for Long Period Structure Using Air Floating Technique: Investigation of Fundamental Performance
Authors: Furuya Osamu , Kurabayashi Hiroshi , Takahashi Osamu , Sanpei Kunio , Sakamoto Shoichi , Yamazaki Koji , Muto Manabu
Published: November 2018

Natural period of architectural structure have been longer to be high-rise in recent years. Tuned Mass Damper (TMD) is applied for the structural response reduction in such a long period structure. In general since there are a lot of design cases using a guide rail for linear motion guide of the mass in TMD, the friction coefficient in assembled TMD becomes almost from 3/1000 to 5/1000. The friction coefficient leads an important problem in view point of performance design for long period structures because of that the friction force becomes a large compared with starting inertia force.

In this study, new type TMD with air pressure floating technique has been examined to reduce a friction force for starting inertia force, and to set 0.01 m/s2 in starting acceleration as a performance target. This paper shows the evaluation results for fundamental performance from static loading test and shaking table test.
Study on Applicability of Master Curve Methodology Using Miniature C(T) Specimen to a Reactor Pressure Vessel With Low Upper Shelf Energy
Authors: Yoshimoto Kentaro , Hirota Takatoshi , Sakamoto Hiroyuki , Oshikiri Masato , Tsutsumi Kazuya , Murakami Takeshi
Published: November 2018

Miniature compact tension (Mini-C(T)) specimen can be an effective tool by utilizing together with Master Curve (MC) methodology for fracture toughness evaluation of irradiated reactor pressure vessel (RPV) steels. Recently, Mini-C(T) specimen has been incorporated into the Japanese standard test method related to MC methodology, JEAC4216-2015 and several studies were found focusing on applicability of Mini-C(T) specimen to irradiated RPV materials. However, there exist some other issues to be resolved considering application to irradiated materials. One of them is violation against the limitation criteria for ductile crack growth (DCG) specified in the standards. In general, upper shelf energy (USE) of RPV materials tends to decrease as well as shift in Charpy transition temperature due to neutron irradiation embrittlement. It may cause reduction in resistance of material against DCG and this leads to the problem peculiar to low USE materials such that the limitation for DCG might be dominant rather than that for KJclimit. Therefore, it is possible to fail to obtain valid KJc data even within valid temperature range of MC methodology, i.e. −50°C ≤ T-To ≤ 50°C, for low USE materials using Mini-C(T) specimens.

In this study, the RPV steel with USE lower than 68J was made simulating reduction of USE due to neutron irradiation. Fracture toughness tests were performed using Mini-C(T) specimens as well as the standard 1T-C(T) specimens. Based on the test results, the validity for DCG limitation was also evaluated for each datum by post-test observation of fracture surface. Additionally, effectiveness of added side grooves and double thickness of specimen was examined as a countermeasure for Mini-C(T) specimen.
Trial for United Representation of Monotonic Stress-Strain Relations of Various Alloys
Authors: Takahashi Yukio
Published: November 2018

Inelastic analysis considering individual material behavior is expected to play a more and more important role in design and fitness-for-service assessment of various pressure-retaining components. Constitutive model is a fundamental element of such an analysis and modeling of stress-strain relations under uniaxial loading constitutes its basis. Some formulae for describing stress-strain relations under monotonically increasing loading have been developed and incorporated in some codes to provide a guidance for elastic-plastic analysis. The author has been trying to find alternative formulae to improve the accuracy and widen the applicability. A simple formula based on the Swift-type equation was derived as a result of systematic analysis of the test data on a number of materials used in nuclear power plants. An alternative expression was also developed in order to circumvent the deficiency observed in ferritic steels. All the constants in these expressions were represented by the functions of temperature, yield stress and tensile strength to make it possible to apply them without further information. Formulae were found to be applicable to various materials such as austenitic stainless steels, high- and medium-strength ferritic steels and some of Nicked based alloys.
Effects of Nut Thinning due to Corrosion on the Sealing Performance in Bolted Flange Joints Under Internal Pressure
Authors: Kikuchi Tsutomu , Tsuji Hirokazu , Tsurumi Daichi
Published: November 2018

In the damage evaluation (and analysis) of the bolted flange joints, it is most important to evaluate the reduction in the sealing performance. Although the marginal nut height found by Alexander’s theory [1] serves as a value smaller about 20% than standard nut height, even if it becomes thin 20% or more on a track record and experience, leakage does not occur. In this study the effects of nut thinning due to corrosion on the sealing performance in 3-inch bolted flange joints under internal pressure by use of FEM calculations. The following results are obtained the relationship between stripping bolt load and nut height is developed, and the marginal nut height for the sealing performance is calculated.
Development of Seismic Countermeasures Against Cliff Edges for Enhancement of Comprehensive Safety of Nuclear Power Plants: Cliff Edges Relevant to NPP Building System
Authors: Nishida Akemi , Choi Byunghyun , Yamano Hidemasa , Takada Tsuyoshi
Published: November 2018

This study identified and quantified possible cliff edge effects through a seismic safety evaluation of a nuclear power plant, based on the concepts of risk and defense in depth. Cliff edges of the both physical and knowledge-oriented type were considered in this study. We investigated a seismic isolation effect, etc., for physical cliff edges, and the modeling of the target structure, boundary conditions, etc., for knowledge-oriented cliff edges.

Response analysis was performed using a sway-rocking (SR) model and a three-dimensional model of the target building. The seismic isolation effect of the base-isolated building was confirmed by comparison to the results of earthquake-resistant building. In the case of a collision with the retaining wall of the base-isolated building, the level of damage was found to depend on the modeling of the collision condition assumed. On the other hand, the study confirmed the differences between the results from the SR model and the three-dimensional model. And the greater fidelity of the three-dimensional model was also confirmed. This paper presents and discusses these results.
Integral Mean of Yield Concept Applied to Thermal Hot Spots: Validation of a Level 2 Damage Assessment Method
Authors: Kwok Henry , Yuen Simon , Penso Jorge
Published: November 2018

The overall framework for a Level 2 assessment of local thermal hot spot in pressure vessels was first developed by Seshadri [1]. The assessment procedure invokes the concept of integral mean of yield and the concept on a reference volume to determine the reduction of load capacity caused by hot spot damage. This paper investigates the accuracy of this assessment by comparing the results of the Level 2 assessment with a Level 3 assessment (inelastic finite element analysis). Three examples with varying pressure component and hot spot sizes are considered. The comparison yielded a low variance between the Level 2 and Level 3 assessments with the Level 2 assessment being more conservative.
Sulfidation Rate Prediction on Tube-to-Tubesheet Joints in a Waste Heat Boiler in a Sulphur Plant
Authors: Ju Feng , Miller Allen , Yuen Simon , Tkachyk Brian
Published: November 2018

Sulfidation corrosion of the carbon steel tubes at the tube-to-tubesheet joint often governs the life of waste heat boilers in sulphur recovery plants. Conventional tube joints typically have a welded joint located at the hot-side face of the tubesheet. An alternative design involves welding the tubesheet joint at the cold-side face of the tubesheet, close to the boiler feed water. The alternative design also employs stainless steel cladding on the tubesheet face and a tube-hole sleeve selectively at high-temperature locations. Finite element heat transfer analysis is used to establish the thermal profiles of the conventional and the alternative designs. From the worked example, the alternative design provided a lower metal temperature by approximately 80 °F at the joint, as compared to the conventional tube joint. Sulfidation rate prediction based on a sample gas composition using ASSET (Alloy Selection System for Elevated Temperatures) Software predicts that the alternative design can reduce the sulfidation rate by 35% because of the lower metal temperature.
Methodology for Identifying Blunt Flaws Using Ultrasonic In-Service Inspection Data
Authors: Jyrkama M. I. , Pandey M. D. , Li M.
Published: November 2018

This paper presents a methodology for identifying blunt flaws in piping using in-service data from ultrasonic inspection tools. The method is applicable to data obtained from predetermined inspection grids, or directly from bracelet or array type inspection tools. The flaw edge and size are identified by calculating the three-dimensional slope vector (i.e., magnitude and direction) of each point in the kriging interpolated wall thickness profile. The transition from a steeper slope to a relatively flat profile is then used by a search algorithm to determine the flaw edge.

The method is applied to the flaw assessment of feeder piping in CANDU nuclear reactors. The results show that in addition to identifying blunt flaws, the developed methodology also provides a convenient way for characterizing the flaw dimensions for structural integrity assessment. The uncertainty in the results is mainly attributed to the signal loss and coverage error associated with the inspection data.
Detection of Creep Degradation on Collapsed Membrane Wall From P265GH Pressure Purpose Steel by Ultrasonic Testing
Authors: Zavadil Tomáš
Published: November 2018

Creep failure of the pressure vessels operated at high temperatures in power and petrochemical industry is a frequent reason of its collapse. Some ultrasonic properties, as the ultrasonic waves’ velocity, are sensitive to change of material properties due to thermally induced degradation processes, especially plastic deformation. The article discusses possible applications of ultrasonic testing to detect creep degradation process based on results of measurements performed on collapsed membrane wall from P265GH pressure purpose steel. The methodology may help with selection of potentially critical areas on pressure equipment under operation prior its further investigation while performing e.g. residual life assessment.
Success of trabeculectomy surgery in relation to cataract surgery: 5-year outcomes
Authors: Mathew Rashmi G , Parvizi Sahar , Murdoch Ian E
Published: November 2018

Aims

To compare success proportions at 5 years in three surgical groups: group 1, trabeculectomy alone; group 2, trabeculectomy followed by cataract surgery within 2 years; and group 3, trabeculectomy performed on a pseudophakic eye.

Methods

A retrospective cohort study. 194 eyes of 194 patients were identified with at least 5 years’ follow-up post trabeculectomy (N=85, 60 and 49 in groups 1, 2 and 3, respectively).

Main outcome measures

1. Primary outcome measure: intraocular pressure (IOP) at 5 years post-trabeculectomy surgery, 2.Secondary outcome measure: change in visual acuity at 5 years.

Results

At 5 years, the mean IOP (SD) was 12.9 (3.5), 12.5 (4.8) and 12.7 (4.8) mm Hg in groups 1, 2 and 3, respectively. Overall success was almost identical, 58%, 57% and 59% in groups 1, 2 and 3, respectively. There was no significant difference between the groups in terms of percentage IOP reduction, number of medications, proportion restarting medication and reoperation rates at 5 years. Logistic regression for an outcome of failure showed men to be at increased risk of failure OR 1.97 (95% CI 1.10 to 3.52, p=0.02). Nearly 80% of patients retained or improved their vision following their initial trabeculectomy.

Conclusions

The sequence in which surgery is carried out does not appear to affect trabeculectomy function at 5 years, success being similar to trabeculectomy alone. In our study, men may be at increased risk of failure.
Cluster randomised controlled trial of an online intervention to prevent ecstasy and new psychoactive substance use among adolescents: final results and implications for implementation
Authors: Champion Katrina E , Newton Nicola Clare , Stapinski Lexine , Teesson Maree
Published: November 2018

Objectives

To evaluate the effectiveness of the onlineClimate Schools: Ecstasy and Emerging Drugs moduleover 2 years, and examine the impact of intervention dose on outcomes.

Design

Cluster randomised controlled trial.

Setting

Secondary schools in Australia.

Participants

1126 students (aged 14.9 years) from 11 schools.

Intervention

Five schools were randomly allocated to the four-lesson internet-basedClimate Schools: Ecstasy and Emerging Drugsmodule. This universal intervention uses cartoon storylines to deliver harm-minimisation information about ecstasy and new psychoactive substances (NPS). It was delivered during health education classes over 4 weeks. Six schools were randomised to the control group (health education as usual). Participants were not blinded to intervention allocation.

Outcomes measures

Students completed self-report surveys at baseline, post-test, 6, 12 and 24 months post-baseline. Intentions to use ecstasy and NPS (including synthetic cannabis and synthetic stimulants), knowledge about ecstasy and NPS and lifetime use of ecstasy and NPS were assessed. This paper reports the results at 24 months post-baseline.

Analysis

Mixed effects regressions were conducted to analyse intervention effects from baseline to 24 months. Post hoc analyses using Inverse Probability of Treatment Weighting compared controls with students who: i) completed all four lessons (‘full dose’) and ii) partially completed the intervention (≤three lessons, ‘incomplete dose’).

Results

Primary analyses found that controls were significantly more likely to intend on using synthetic cannabis compared with intervention group students (OR=3.56, p=0.01). Results from the weighted analyses indicated that controls reported significantly lower knowledge about ecstasy (p=0.001) and NPS (p=0.04) compared with the full-dose group. No significant differences were observed between the incomplete dose and control groups.

Conclusions

The online intervention was effective in modifying students’ intentions to use synthetic cannabis up to 24 months; however, this study highlights the importance of delivering prevention programmes in full to maximise student outcomes.

Trial registration number

ACTRN12613000708752.
Protective effects of oral anticoagulants on cerebrovascular diseases and cognitive impairment in patients with atrial fibrillation: protocol for a multicentre, prospective, observational, longitudinal cohort study (Strawberry study)
Authors: Saji Naoki , Sakurai Takashi , Ito Kengo , Tomimoto Hidekazu , Kitagawa Kazuo , Miwa Kaori , Tanaka Yuji , Kozaki Koichi , Kario Kazuomi , Eto Masato , Suzuki Keisuke , Shimizu Atsuya , Niida Shumpei , Hirakawa Akihiro , Toba Kenji
Published: November 2018

Introduction

Non-valvular atrial fibrillation (NVAF) is known as a robust risk factor for stroke. Recent reports have suggested a risk of dementia with NVAF, but much remains unknown regarding the relationship between this mechanism and the potential protective effects of novel anticoagulants (direct oral anticoagulants (DOACs), or non-vitamin K oral anticoagulants).

Methods and analysis

This study, the strategy to obtain warfarin or DOAC’s benefit by evaluating registry, is an investigator-initiated, multicentre, prospective, observational, longitudinal cohort study comparing the effects of warfarin therapy and DOACs on cerebrovascular diseases and cognitive impairment over an estimated duration of 36 months. Once a year for 3 years, the activities of daily living and cognitive functioning of non-demented patients with NVAF will be assessed. Demographics, risk factors, laboratory investigations, lifestyle, social background and brain MRI will be assessed.

Ethics and dissemination

This protocol has been approved by the ethics committee of the National Center for Geriatrics and Gerontology (No. 1017) and complies with the Declaration of Helsinki. Informed consent will be obtained before study enrolment and only coded data will be stored in a secured database. The results will be published in peer-reviewed journals and presented at scientific meetings to ensure the applicability of the findings in clinical practice.

Trial registration number

UMIN000025721.
Between-hospital and between-neighbourhood variance in trauma outcomes: cross-sectional observational evidence from the Detroit metropolitan area
Authors: Sall Lauren , Hayward R David , Fessler Mary M , Edhayan Elango
Published: November 2018

Objective

Disparities in treatment outcomes for traumatic injury are an important concern for care providers and policy makers. Factors that may influence these disparities include differences in risk exposure based on neighbourhood of residence and differences in quality of care between hospitals in different areas. This study examines geographical disparities within a single region: the Detroit metropolitan area.

Design

Data on all trauma admissions between 2006 and 2014 were obtained from the Michigan State Inpatient Database. Admissions were grouped by patient neighbourhood of residence and admitting hospital. Generalised linear mixed modelling procedures were used to determine the extent of shared variance based on these two levels of categorisation on three outcomes. Patients with trauma due to common mechanisms (falls, firearms and motor vehicle traffic) were examined as additional subgroups.

Setting

66 hospitals admitting patients for traumatic injury in the Detroit metropolitan area during the period from 2006 to 2014.

Participants

404 675 adult patients admitted for treatment of traumatic injury.

Outcome measures

In-hospital mortality, length of stay and hospital charges.

Results

Intraclass correlation coefficients indicated that there was substantial shared variance in outcomes based on hospital, but not based on neighbourhood of residence. Among all injury types, hospital-level differences accounted for 12.5% of variance in mortality risk, 28.5% of variance in length of stay and 32.2% of variance in hospital charges. Adjusting the results for patient age, injury severity, mechanism and comorbidities did not result in significant reduction in the estimated variance at the hospital level.

Conclusions

Based on these data, geographical disparities in trauma treatment outcomes were more strongly attributable to differences in access to quality hospital care than to risk factors in the neighbourhood environment. Transfer of high-risk cases to hospitals with greater institutional experience in the relevant area may help address mortality disparities in particular.
Impoverishment and catastrophic expenditures due to out-of-pocket payments for antenatal and delivery care in Yangon Region, Myanmar: a cross-sectional study
Authors: Myint Aye Nyein Moe , Liabsuetrakul Tippawan , Htay Thein Thein , Wai Myint Myint , Sundby Johanne , Bjertness Espen
Published: November 2018

Objectives

(1) To assess the levels of impoverishment and catastrophic expenditure due to out-of-pocket (OOP) payments for antenatal care (ANC) and delivery care in Yangon Region, Myanmar; and (2) to explore the determinants of impoverishment and catastrophic expenditure.

Design, setting and participants

A community-based cross-sectional survey among women giving birth within the past 12 months in Yangon, Myanmar, was conducted during October to November 2016 using three-stage cluster sampling procedure.

Outcome measures

Poverty headcount ratio, normalised poverty gap and catastrophic expenditure incidence due to OOP payments in the utilisation of ANC and delivery care as well as the determinants of impoverishment and catastrophic expenditure.

Results

Of 759 women, OOP payments were made by 75% of the women for ANC and 99.6% for delivery care. The poverty headcount ratios after payments increased to 4.3% among women using the ANC services, to 1.3% among those using delivery care and to 6.1% among those using both ANC and delivery care. The incidences of catastrophic expenditure after payments were found to be 12% for ANC, 9.1% for delivery care and 20.9% for both ANC and delivery care. The determinants of impoverishment and catastrophic expenditure were women’s occupation, number of household members, number of ANC visits and utilisation of skilled health personnel and health facilities. The associations of the outcomes with these variables bear both negative and positive signs.

Conclusions

OOP payments for all ANC and delivery care services are a challenge to women, as one of fifteen women become impoverished and a further one-fifth incur catastrophic expenditures after visiting facilities that offer these services.
Determining the optimal time for liberation from renal replacement therapy in critically ill patients: protocol for a systematic review and meta-analysis (DOnE RRT)
Authors: Al Saadon Abdalrhman , Katulka Riley , Sebastianski Meghan , Featherstone Robin , Vandermeer Ben , Gibney R T Noel , Rewa Oleksa G , Bagshaw Sean M
Published: November 2018

Introduction

Renal replacement therapy (RRT) is a complex and expensive form of life-sustaining therapy, reserved for our most acutely ill patients. While a number of randomised trials have evaluated the optimal timing to start RRT among critically ill patients in the intensive care unit (ICU), there has been a paucity of trials providing guidance on when and under what circumstances to ideally liberate a patient from RRT. We are conducting a systematic review and meta-analysis to identify clinical and biochemical markers that predict kidney recovery and successful liberation from acute RRT among critically ill patients with acute kidney injury.

Methods and analysis

Our comprehensive search strategy was developed in consultation with a research librarian and independently peer-reviewed by a second librarian. We will search electronic databases: Ovid Medline, Ovid Embase and Wiley Cochrane Library. Selected grey literature sources will also be searched. Our search strategies will focus on concepts related to RRT (ie, intermittent haemodialysis, slow low-efficiency dialysis, continuous renal replacement therapy), intensive care (ie, involving any ICU setting) and discontinuation of therapy (ie, either clinical, physiological and biochemical parameters of weaning acute RRT) from 1990 to October 10, 2017. Citation screening, selection, quality assessment and data abstraction will be performed in duplicate. Studies will, where possible, be pooled in statistical meta-analysis. When deemed sufficiently clinically homogenous, and we have four or more studies reporting, sensitivities and specificities will be pooled simultaneously using a hierarchical summary receiver operator characteristic curve and bivariate analysis.

Ethics and dissemination

Our systematic review will synthesise the literature on clinical and biochemical markers that predict liberation from RRT. Research ethics approval is not required.

Trial registration number

CRD42018074615.
Influences of facial disfigurement and social support for psychosocial adjustment among patients with oral cancer in Taiwan: a cross-sectional study
Authors: Wang Tsae-Jyy , Lu Ming-Hsiu , Kuo Pei-Ling , Chen Yi-Wei , Lee Shu-Chiung , Liang Shu-Yuan
Published: November 2018

Objective

To explore the influences of facial disfigurement and social support for psychosocial adjustment in patients with oral cancer.

Design

A cross-sectional design was used for the study.

Participants and setting

A convenience sample of 77 patients with oral cancer was recruited from the otolaryngology and oral and maxillofacial surgery outpatient clinics of three general hospitals in Taiwan.

Measures

Data were collected using the study questionnaires, including the Facial Disfigurement Scale, the Social Support Scale and the Psychosocial Adjustment to Illness Scale.

Results

The mean score on the Psychosocial Adjustment to Illness Scale was 413.01 (SD=32.32); 71.4% of the participants were maladjusted. Results of multiple regression analysis showed statistically significant main effects of tumour site (beta=0.37), facial disfigurement (beta=0.35) and social support (beta=−1.01), and the interaction effect of facial disfigurement and social support (beta=0.79) (all p<0.05) on psychosocial adjustment after controlling for other sociodemographic and clinical variables. All variables together explained 62% of the variance in psychosocial adjustment (F(16, 55)=14.98, p<0.001).

Conclusions

The level of psychosocial adjustment in patients with oral cancer was suboptimal. Poorer psychosocial adjustment was reported by patients with more severe facial disfigurement and less social support. Patients with cancers in other areas of the oral cavity also reported poorer psychosocial adjustment than patients with cancers in the buccal mucosa. Medical professionals may use these variables to identify higher risk groups for early intensive intervention.
Eczema and subsequent suicide: a matched case–control study
Authors: Drucker Aaron Mark , Thiruchelvam Deva , Redelmeier Donald A
Published: November 2018

Objective

To assess the association of eczema with a patient’s subsequent risk of death from suicide. We hypothesised that persistent eczema would be associated with an increased risk for death from suicide.

Design

Double matched case–control study.

Setting

General population of Ontario, Canada.

Participants

Patients 15–55 years old. We identified cases of suicide from coroners’ reports between 1 January 1994 and 31 December 2014 and matched 1:2 with alive controls based on age, sex and socioeconomic status.

Exposure

The primary predictor was a history of persistent eczema, defined as five or more physician visits for the diagnosis over the preceding 5 years.

Main outcome and measure

Logistic regression to estimate the association between eczema and death from suicide.

Results

We identified 18 441 cases of suicide matched to 36 882 controls over the 21-year accrual period. Persistent eczema occurred in 174 (0.94%) suicide cases and 285 (0.77%) controls yielding a 22% increased risk of suicide associated with persistent eczema (OR 1.22, 95% CI 1.01 to 1.48, p=0.037). In mediation analyses, this association was largely explained through major suicide risk factors. Two-thirds of patients with eczema who died from suicide had visited a physician in the month before their death and one in eight had visited for eczema in the month before their death. Among patients who died by suicide, jumping and poisoning were relatively more frequent mechanisms among patients with eczema.

Conclusions

Patients with persistent eczema have a modestly increased subsequent risk of death from suicide, but this is not independent of overall mental health and the absolute risk is low. Physicians caring for these patients have opportunities to intervene for suicide prevention.