bluuebunny/crossref_metadata_2025 huggingface dataset:
Research and Development of Three-Dimensional Isolation System for Sodium-Cooled Fast Reactor: Part 2 — Details of Characteristics for Disc Springs and Oil Dampers on Basis of Full-Scale Loading Tests
Authors: Somaki Takahiro , Fukasawa Tsuyoshi , Miyagawa Takayuki , Yamamoto Tomohiko , Hibako Yoshifumi , Okamoto Masanari , Noda Osamu , Ishizuka Futoshi
Published: November 2018

Being compatible with the seismic and thermal loads for the large Sodium-cooled Fast Reactor (SFR), the three-dimensional isolation system is inevitable technology. The three-dimensional isolation system consists of the thick rubber bearings, the disc springs and the oil dampers.

Since the isolation performances on the rubber bearings in the horizontal direction have been revealed by the previous studies [1], the vertical isolation performance and characteristics such as restoring force and damping performance should be clarified by loading tests to build the analytical model. This paper presents these fundamental vertical isolation characteristics obtained by loading tests with full-scaled disc springs and oil dampers. The disc springs as the vertical restoring forces have 700 mm in external diameter and 34 mm in thickness. The oil dampers have the maximum damping force of 2,000 kN at the velocity of 0.25 m/s. The disc spring is one of the largest size, and the oil damper is one of the largest damping capacity in Japan.

The static loading tests such as incremental cyclic loadings under the supporting load were conducted to investigate the restoring force characteristics for the disc springs. The dynamic loading using sinusoidal waves with varied input frequencies or the seismic response waves obtained by seismic response analysis were conducted to investigate the damping performance for the oil dampers.

The applicability of the design method and the analytical model for disc springs and oil dampers were demonstrated by the restoring force characteristics obtained from tests.

It should be noted, this paper is in series from Part 1.
Research and Development of Three-Dimensional Isolation System for Sodium-Cooled Fast Reactor: Part 1 — Proposal of Analytical Models Based on Loading Tests
Authors: Fukasawa Tsuyoshi , Okamura Shigeki , Somaki Takahiro , Miyagawa Takayuki , Uchita Masato , Yamamoto Tomohiko , Watakabe Tomoyoshi , Fujita Satoshi
Published: November 2018

This paper describes that the analytical model for the three-dimensional isolation system [1], which consists of thick rubber bearings, disc springs and oil dampers, is created through loading tests. The new-type analytical models of each element are proposed to improve the prediction accuracy of the seismic response analysis.

The concept of the three-dimensional isolation system has been proposed to ensure the structural integrity for large reactor vessels. The primary specifications of the three-dimensional isolation system are a horizontal natural period of 3.4 s and a vertical natural period of 0.33 s. The investigations of horizontal isolation performances have been conducted for the various types of isolation devices, beginning with rubber bearings, whereas the previous studies focused on the vertical isolation performances are only a few. Hence, isolation characteristics, such as restoring force and damping force, should be clarified by loading tests using vertical seismic isolation elements, and analytical model to assess the seismic response should be identified on the basis of the loading test results.

This paper presents a new analytical model with providing of the differential equations to improve the prediction accuracy and demonstrates the seismic performance, including beyond-design-basis ground motion, for the three-dimensional isolation system by the seismic response analysis.
New Generation of Monitoring Systems: From Measurement to Numerical Simulation
Authors: Jouan Benoît , Heinz Benedikt , Pascan Oana Zenaida
Published: November 2018

This paper presents a new method for monitoring systems with direct coupling of measurement data and a finite element model of a mechanical component. In the presented first case study the measurement data received from a monitoring system is coupled with a finite element model developed in Code_Aster, showing the possibility of minimizing the efforts of data-model coupling on complex components.

A thermo-mechanical calculation of a generic regenerative heat exchanger of a nuclear power plant will be used as an example to describe the opportunities and the limitations of the use of numerical simulation in modern monitoring systems. The experimental measurements and the thermo-mechanical numerical simulation process will be presented. The projection hypothesis that allows the transition from locally measured temperature to the numerical model will be described. The relation between computing time, sampling rate of the data acquisition system and refinement of the numerical mesh will be analyzed and discussed in terms of computation perspective.

The paper explains how the measurement data can be projected on the mesh of a mechanical component with Code_Aster and how the numerical simulation can be fed on the measurement data. In an outlook, the use of this method in future monitoring systems will be discussed under consideration of real world problems and applications in nuclear power stations.
Structural Stability Evaluation of Independent Spent Fuel Storage Casks
Authors: Kwon Gunup , Hoang Phuong , Ata Khaled
Published: November 2018

Most nuclear power plants in the US store the spent fuels in independent spent fuel storage casks and these casks are typically placed on concrete pads outside of the fuel handling building. Under plant design basis events, the spent fuel storage casks should maintain stability without tip-over or direct contact with each other. Sliding and rocking of the casks can be determined using nonlinear dynamic analyses under artificial acceleration input motions. Alternatively, approximate equations developed for sliding and rocking of rigid bodies are used as shown in ASCE 4-16. However, these equations consider rocking and sliding as two separate events. Due to the shortcoming of the approximate method, many power plant owners are required to perform extensive nonlinear analyses to ensure cask stability during seismic events. In this study, an independent spent fuel storage cask model is developed and nonlinear dynamic analyses are conducted with seismic input motions that meet the current US Nuclear Regulatory Commission requirements. The analysis results are compared with the approximate method in ASCE 4-16. Based on the comparison, recommendations are made for the use of the approximate approach.
Numerical Approach to Determine the Correct Puncture Bar Length for the IAEA Puncture Bar Drop Test
Authors: Weber Mike , Ballheimer Viktor , Wille Frank , Zencker Uwe
Published: November 2018

Among other mechanical tests the 1 meter drop onto a steel puncture bar shall be considered for accident safe packages for the transport of radioactive material. According with the IAEA regulations “the bar shall be of solid mild steel of circular section, 15.0 ± 0.5 cm in diameter and 20 cm long, unless a longer bar would cause greater damage ...”. The most damaging puncture bar length can be estimated by iterative processes in numerical simulations. On the one hand, a sufficient puncture bar length has to guarantee that shock absorbers or other attachments do not prevent or reduce the local load application to the package, on the other hand, a longer and thus less stiff bar causes a smaller maximum contact force. The contrary influence of increasing puncture bar length and increasing effective drop height shall be taken into account if a shock absorber is directly placed in the target area. The paper presents a numerical approach to identify the bar length that causes maximum damage to the package. Using the example of two typical package masses the sensitivity of contact forces and puncture bar deformations to the initial length are calculated and assessed with regard to the international IAEA package safety requirements.
Experimental Investigations of the Burning Behaviour of Transport Package Impact Limiters and of Fire Spread Impact Onto the Cask
Authors: Erenberg Marina , Bletzer Claus , Feldkamp Martin , Musolff André , Nehrig Marko , Wille Frank
Published: November 2018

Accident safe packages for the transport of spent nuclear fuel and high-level waste shall fulfil international IAEA safety requirements. Compliance is shown by consecutive mechanical and thermal testing. Additional numerical analysis are usually part of the safety evaluation. For damage protection some package designs are equipped with wood filled impact limiters encapsulated by steel sheets. The safety of these packages is established in compliance with IAEA regulations. Cumulative mechanical and fire tests are conducted to achieve safety standards and to prevent loss of containment. Mechanical reliability is proven by drop tests. Drop testing might cause significant damage of the impact limiter steel sheets and might enable sufficient oxygen supply to the impact limiter during the fire test to ignite the wood filling. The boundary conditions of the fire test are precisely described in the IAEA regulatory. During the test the impact limiter will be subjected to a 30 minute enduring fire phase. Subsequent to the fire phase any burning of the specimen has to extinguish naturally and no artificial cooling is allowed. At BAM a large-scale fire test with a real size impact limiter and a wood volume of about 3m3 was conducted to investigate the burning behaviour of wood filled impact limiters in steel sheet encapsulation. The impact limiter was equipped with extensive temperature monitoring equipment. Until today burning of such impact limiters is not sufficiently considered in transport package design and more investigation is necessary to explore the consequences of the impacting fire. The objective of the large scale test was to find out whether a self-sustaining smouldering or even a flaming fire inside the impact limiter was initiated and what impact on the cask is resulting. The amount of energy, transferred from the impact limiter into the cask is of particular importance for the safety of heavy weight packages. With the intention of heat flux quantification a new approach was made and a test bench was designed.
Temperature Prediction of a TN-32 Used Nuclear Fuel Canister Subjected to Vacuum Drying Conditions
Authors: Higley Megan , Hadj-Nacer Mustafa , Greiner Miles
Published: November 2018

In this work, a geometrically-accurate two-dimensional (2D) computational fluid dynamic (CFD) model of a used nuclear fuel cask, that can contain up to 32 pressurized water reactor (PWR) used nuclear fuel (UNF) assemblies, is constructed. This model is similar to the TN-32 cask employed in the ongoing high-burnup (HBU) Spent Fuel Data Project lead by the Electric Power Research Institute (EPRI). This model is used to predict the peak cladding temperature under vacuum drying conditions. Due to the symmetry of the cask, only one-eighth of the cross-section is modeled. Steady-state simulations that include the temperature-jump boundary conditions at the gas-solid interfaces are performed for different heat generation rates in the fuel regions and a range of dry helium pressures, from ∼105 to 100 Pa. These simulations include conduction within solid-gas regions and surface-to-surface radiation across all gas regions. The peak cladding temperatures are reported for various heat generation rates and rarefaction conditions, along with the maximum allowable heat generation that brings the cladding temperatures to the radial hydride formation limit. The results showed that the decrease of helium pressure significantly increased the temperature of the cladding material compared to the atmospheric pressure condition.
Microstructural Characterization of Base Material and Welded Joints of Serviced and Non-Serviced Coke Drums
Authors: Romo S. A. , Barborak D. , Bedoya J. , Penso J. , Ramirez A. J.
Published: November 2018

Coke drums are massive pressure vessels used in the oil and gas industry, which are subjected to demanding cyclic thermomechanical loading. Such conditions generate severe plastic deformation that leads to bulging and cracking during service due to low-cycle fatigue. The cracks are often repaired in programed maintenance shutdowns, and the repair procedures can be significantly different depending on the organization and failure characteristics. In this work, two types of weld repairs are evaluated after six months of service: (1) a full-excavation crack weld repair, and (2) a partial-excavation crack weld overlay repair. The repair welds were executed on a 1.25Cr-0.5Mo steel coke drum after 20 years of service. This work evaluates the microstructure of the base material, the fabrication circumferential welds, and the weld repairs. The results show that, after prolonged exposure to elevated temperatures, the originally normalized and tempered heat-treated steel microstructure has undergone severe aging. Thermodynamic equilibrium and para-equilibrium calculations were used to determine the carbide formation sequence, and SEM analysis was used to characterize the carbides present on the as-fabricated and aged microstructures. Analysis of the repaired regions did not reveal new cracks.
A Comparative Evaluation of Finite Element Modeling of Creep Deformation of Fuel Channels in CANDU® Nuclear Reactors
Authors: Tallavo F. J. , Pandey M. D. , Jyrkama M. , Christodoulou N. C. , Bickel G. A. , Leitch B. W.
Published: November 2018

A key element of the fuel channel life cycle management in CANDU® nuclear reactors is to prevent contact between the pressure tube (PT) and the calandria tube (CT) in a fuel channel. By preventing PT-CT contact, the development of hydride blisters and delayed hydride cracking of the PT can be avoided. The PT-CT contact is a result of in-reactor deformation due to irradiation induced creep of the fuel channel assembly. Excessive sagging of the PT can also interfere with the free passage of the fuel bundles when the channel is refueled. Contact of the CT with reactor control mechanisms located horizontally between the fuel channels can result from excessive sag of the CT. The prediction of dimensional changes due to in-reactor creep and the time of PT-CT contact is calculated using finite element modeling of the fuel channel with appropriate creep constitutive laws describing PT and CT deformation. The three-dimensional nature of creep deformation of fuel channels can be approximated by a one-dimensional finite element model (1D-FEM), which is a computationally tractable problem. However, the simplifications of a 1D-FEM model come at the expense of loss of prediction accuracy. This paper compares creep deformation analysis of fuel channels using 1D-FEM and 3D-FEM models. The comparison is based on PT and CT sag profiles as well as on PT-CT gap at different time intervals during service of the fuel channel. Results from the comparative analysis show that the 1D-FEM model predicts greater values of PT-CT gap. The difference in gap predicted between both FEM models increases rapidly when the minimum gap is located in the outlet span. At 250,000 equivalent full power hours, the 1D-FEM model overestimate the gap by 1.12 mm with respect to the 3D-FEM model.
Fitness for Service Assessment and Repair of the Liner of a High Pressure Heat Exchanger
Authors: van Zyl Gys , Al-Harthi Sultan
Published: November 2018

A high pressure carbamate condenser (HPCC) is a shell and tube heat exchanger with low pressure steam/condensate on the shell side and high pressure carbamate solution on the tube side. The inlet channel of the exchanger is protected from the internal corrosive environment by means of an austenitic stainless steel liner. During the first internal inspection after commissioning, a bulge was observed in the liner where a pass partition plate is joined to the liner. Surface-breaking cracks were observed at the partition plate to liner welds in the bulged region. The cracks were removed by shallow grinding, but a fitness-for-service assessment was required to evaluate the suitability of the bulged liner for continued service. Due to the complexity of the geometry, a handheld 3D geometry scanner was used to accurately measure the deformed shape of the bulge. Using the measured geometry, a finite element model was developed and used to perform a level 3 fitness for service assessment. This paper will describe the assessment procedure in detail as well as the complex internal repairs that were ultimately implemented in order to restore the integrity of the equipment.
Evolution of Temperature, Microstructure and Inter-Granular Stresses During Directionally Solidification Process of a Ni-Based Superalloy
Authors: Torfeh Maryam , Aghazadeh Jamshid , Nakhodchi Soheil
Published: November 2018

In order to gain a better understanding of the detrimental effects of grain boundaries on the creep and fatigue life of a nickel based directionally solidified super alloys, the effect of the grain mis-orientation and temperature changes on the internal stresses were investigated. The changes of cooling rate, nuclei count and stress level and components in different parts of the casting were considered during solidification process in a Bridgeman furnace. During solidification, constriction of grain growth in one direction, which is due to the heat transfer direction, eliminates grains with large mis-orientations. The remaining grains are close to [001] direction. Temperature profile of the modeled carrot samples demonstrated a significant variation in the cooling rate along the axis of the sample. The mis-orientation of the grains was also characterized. Stress components and effective stress were calculated and it was shown that the effective stress is lower than the yield stress of the alloy.
Categorization of Dynamic Loading Into Force-Controlled Loading and Displacement-Controlled Loading
Authors: Tamura Ichiro , Matsuura Shinichi , Shimazu Ryuya , Kimura Koji
Published: November 2018

To investigate the behavior of inelastic single-degree-of-freedom systems, the maximum restoring forces and maximum deformations of the systems due to a harmonic excitation are calculated and drawn as a diagram. These systems have restoring forces characterized by bilinear skeleton curve of the kinematic hardening type. The diagram shows two types of characteristics, and the dynamic loadings can be categorized into force-controlled loading and displacement-controlled loading.
Thermal and Structural Analysis of Reactor Vessel Lower Head Considering Core Meltdown Accident
Authors: Luo Juan , Luo Jiacheng , Sun Lei , Tang Peng
Published: November 2018

In the core meltdown severe accident, in-vessel retention (IVR) of molten core debris by external reactor vessel cooling (ERVC) is an important mitigation strategy. During the IVR strategy, the core debris forming a melt pool in the reactor pressure vessel (RPV) lower head (LH) will produce extremely high thermal and mechanical loadings to the RPV, which may cause the failure of RPV due to over-deformation of plasticity or creep. Therefore, it is necessary to study the thermomechanical behavior of the reactor vessel LH during IVR condition. In this paper, under the assumption of IVR-ERVC, the thermal and structural analysis for the RPV lower head is completed by finite element method. The temperature field and stress field of the RPV wall, and the plastic deformation and creep deformation of the lower head are obtained by calculation. Plasticity and creep failure analysis is conducted as well. Results show that under the assumed conditions, the head will not fail due to excessive creep deformation within 200 hours. The results can provide basis for structural integrity analysis of pressure vessels.
Dimensional Changes of Graphite Flakes and Fracture in Tensile Tests of Gray Cast Iron
Authors: Tada Naoya , Uemori Takeshi
Published: November 2018

Gray cast iron has been used as a component in various mechanical parts, such as the blocks and heads of automobile and marine engines, cylinder liners for internal combustion engines, and machine tool bases. It is desirable because of its good castability and machinability, damping characteristics, and high ratio of performance to cost. On the other hand, the weak graphite flakes present in gray cast iron act as stress concentrators and negatively affect the strength of this material. It is therefore important to know the relationship between the distribution of graphite flakes and the strength or fracture of gray cast iron. In this study, a tensile test of gray cast iron was carried out using a plate specimen in a scanning electron microscope, and the microscopic deformation was observed on the surface of specimen. Particularly, the change in the size of graphite flakes during the tensile test was examined, and the observed trend was discussed. We found from the experimental results that the dimensional changes in the graphite flakes varied in the observed area, and that the final fracture occurred in an area where a relatively large dimensional change was observed. This suggests that the fracture location or the critical parts of gray cast iron, can be predictable from the dimensional changes of the graphite flakes at an early stage of deformation.
Acoustically relevant properties of four crude oils at oceanographic temperatures and pressures
Authors: Loranger Scott , Bassett Christopher , Cole Justin P. , Boyle Bret , Weber Thomas C.
Published: November 2018

Inversions of models of broadband acoustic scattering to detect and quantify weakly scattering targets, such as oil droplets in seawater, require precise knowledge of the physical properties that determine scattering. When the characteristic impedance contrast between a target and the surrounding medium is weak, small differences between the true and modeled impedance can cause significant errors in modeled scattering. For crude oil, currently available empirical models of density and sound speed are derived from measurements made at reservoir conditions (high temperature and pressure), which may not be relevant to oceanographic conditions due to phase changes in the oil. Measurements of the density and sound speed, as well as thermal characterization of phase changes via differential scanning calorimetry, of four crude oils at oceanographically relevant temperatures and pressures were made and compared to a commonly used empirical model for sound speed and density. Significant deviations between the measured and modeled values were found and different empirically fit models were developed. A literature review of sound speed data was also performed, and the innovative empirical model shows improvement over the commonly used empirical model for both the data measured here and the measurements in the literature.
Ultrasound tomography in bone mimicking phantoms: Simulations and experiments
Authors: Falardeau Timothe , Belanger Pierre
Published: November 2018

Bone quality assessment for osteoporosis diagnosis is usually performed using dual energy X-ray absorptiometry or X-ray quantitative computed tomography. Recent research demonstrated that both methods are inaccurate in diagnosing osteoporosis since they rely only on the bone mineral density. The literature on bone quantitative ultrasound suggests that ultrasonic waves are sensitive to multiple significant bone parameters such as mechanical properties, the bone volume fraction, and the micro-architecture. Typical ultrasound tomography techniques are limited to image objects with a low speed of sound contrast relative to a background medium. In this study, the possibility of adapting a more advanced ultrasound inversion technique referred to as the hybrid algorithm for robust breast ultrasound tomography for velocity mapping of bone mimicking phantoms was examined. The cortical bone thickness and the cortical bone speed of sound, which are directly related to the bone elastic properties, are parameters strongly correlated with the overall bone quality. A finite element model and an experimental test bench were developed to adapt the hybrid algorithm for robust breast ultrasound tomography to bone quality assessment. Although artefacts were present in the images generated, the results obtained enabled discrimination of a healthy bone phantom over an osteoporotic bone phantom based on the cortical bone thickness and the average cortical bone velocity. The speed of sound inside the cortical region of the bone phantoms was underestimated by 9.38% for the osteoporotic phantom, and by 10.68% for the healthy phantom relative to the values supplied by the bone phantom manufacturer, but there was a difference of 3.97% between the two samples. The difference between the measured cortical bone thickness of the reconstructed image and the X-ray computed tomography images was on average 0.4 mm.
Energy shielding by cavitation bubble clouds in burst wave lithotripsy
Authors: Maeda Kazuki , Maxwell Adam D. , Colonius Tim , Kreider Wayne , Bailey Michael R.
Published: November 2018

Combined laboratory experiment and numerical simulation are conducted on bubble clouds nucleated on the surface of a model kidney stone to quantify the energy shielding of the stone caused by cavitation during burst wave lithotripsy (BWL). In the experiment, the bubble clouds are visualized and bubble-scattered acoustics are measured. In the simulation, a compressible, multi-component flow solver is used to capture complex interactions among cavitation bubbles, the stone, and the burst wave. Quantitative agreement is confirmed between results of the experiment and the simulation. In the simulation, a significant shielding of incident wave energy by the bubble clouds is quantified. The magnitude of shielding can reach up to 90% of the energy of the incoming burst wave that otherwise would be transmitted into the stone, suggesting a potential loss of efficacy of stone comminution. There is a strong correlation between the magnitude of the energy shielding and the amplitude of the bubble-scattered acoustics, independent of the initial size and the void fraction of the bubble cloud within a range addressed in the simulation. This correlation could provide for real-time monitoring of cavitation activity in BWL.
Hearing sensitivity evaluated by the auditory brainstem response in Miniopterus fuliginosus
Authors: Furuyama Takafumi , Hase Kazuma , Hiryu Shizuko , Kobayasi Kohta I.
Published: November 2018

This study evaluated the hearing sensitivity of Miniopterus fuliginosus, a frequency-modulating (FM) bat species, by measuring the auditory brainstem responses in the inferior colliculus. The average audiogram was U-shaped. The mean threshold decreased gradually as the frequency increased from 16 to 40 kHz and then decreased rapidly as the frequency reached 46 kHz, with the peak sensitivity occurring at the terminal portion of the echolocation pulse between frequencies of 44 and 56 kHz. The shape of audiogram of M. fuliginosus is consistent with other FM bats, and is compared with its vocalization behavior.
Mechanistic Basis for Decreased Antimicrobial Susceptibility in a Clinical Isolate of Neisseria gonorrhoeae Possessing a Mosaic-Like
mtr
Efflux Pump Locus
Authors: Rouquette-Loughlin Corinne E. , Reimche Jennifer L. , Balthazar Jacqueline T. , Dhulipala Vijaya , Gernert Kim M. , Kersh Ellen N. , Pham Cau D. , Pettus Kevin , Abrams A. Jeanine , Trees David L. , St Cyr Sancta , Shafer William M.
Published: November 2018

Historically, after introduction of an antibiotic for treatment of gonorrhea, strains of
N. gonorrhoeae
emerge that display clinical resistance due to spontaneous mutation or acquisition of resistance genes. Genetic exchange between members of the
Neisseria
genus occurring by transformation can cause significant changes in gonococci that impact the structure of an antibiotic target or expression of genes involved in resistance. The results presented here provide a framework for understanding how mosaic-like DNA sequences from commensal
Neisseria
that recombine within the gonococcal
mtr
efflux pump locus function to decrease bacterial susceptibility to antimicrobials, including antibiotics used in therapy of gonorrhea.
Development of Thermostable Lyophilized Sabin Inactivated Poliovirus Vaccine
Authors: Shin Woo-Jin , Hara Daiki , Gbormittah Francisca , Chang Hana , Chang Byeong S. , Jung Jae U.
Published: November 2018

Poliomyelitis is a highly contagious disease caused by the poliovirus. While the live attenuated OPV has been the vaccine of choice, a major concern is its ability to revert to a form that can cause paralysis, so-called vaccine-associated paralytic poliomyelitis. Therefore, the new endgame strategy of the Global Polio Eradication Initiative includes the introduction of an IPV. However, the feasibility of the use of current IPV formulations in developing countries is limited, because IPV is insufficiently stable to be purified, transported, and stored under unrefrigerated conditions. We successfully designed the sIPV for use in the dry state that maintains the full vaccine potency in animal models after incubation at ambient temperature. This report provides, for the first time, candidate formulations of sIPV that are stable at elevated temperatures.
Origins and Evolution of the Global RNA Virome
Authors: Wolf Yuri I. , Kazlauskas Darius , Iranzo Jaime , Lucía-Sanz Adriana , Kuhn Jens H. , Krupovic Mart , Dolja Valerian V. , Koonin Eugene V.
Published: November 2018

The majority of the diverse viruses infecting eukaryotes have RNA genomes, including numerous human, animal, and plant pathogens. Recent advances of metagenomics have led to the discovery of many new groups of RNA viruses in a wide range of hosts. These findings enable a far more complete reconstruction of the evolution of RNA viruses than was attainable previously. This reconstruction reveals the relationships between different Baltimore classes of viruses and indicates extensive transfer of viruses between distantly related hosts, such as plants and animals. These results call for a major revision of the existing taxonomy of RNA viruses.
Physical compatibility of pentoxifylline and intravenous medications
Authors: Senarathna S M D K Ganga , Strunk Tobias , Petrovski Michael , Batty Kevin T
Published: November 2018

Objective

To investigate the physical and chemical compatibility of pentoxifylline (PTX) with a wide range of parenteral medications used in the neonatal intensive care setting.

Design

PTX and drug solutions were combined in glass phials and inspected visually for physical incompatibility. The chemical compatibility was evaluated on the basis of PTX concentrations.

Results

Precipitation, colour change or turbidity was not visible in any of the test mixtures, indicating no observed physical incompatibility or apparent risk of blockage in narrow-bore intravenous tubing. The PTX concentration was approximately 2.5% and 4.5% lower when combined with dopamine and amoxicillin, respectively. The PTX concentration ratios for all other combinations were in the range of 99%–102%.

Conclusion

In simulated Y-site conditions, physical compatibility testing of PTX and 30 parenteral medications revealed no evidence of precipitation. Based on PTX concentration tests, it could be prudent to avoid mixing PTX with dopamine or amoxicillin.
Characterisation of neonatal seizures and their treatment using continuous EEG monitoring: a multicentre experience
Authors: Rennie Janet M , de Vries Linda S , Blennow Mats , Foran Adrienne , Shah Divyen K , Livingstone Vicki , van Huffelen Alexander C , Mathieson Sean R , Pavlidis Elena , Weeke Lauren C , Toet Mona C , Finder Mikael , Pinnamaneni Raga Mallika , Murray Deirdre M , Ryan Anthony C , Marnane William P , Boylan Geraldine B
Published: November 2018

Objective

The aim of this multicentre study was to describe detailed characteristics of electrographic seizures in a cohort of neonates monitored with multichannel continuous electroencephalography (cEEG) in 6 European centres.

Methods

Neonates of at least 36 weeks of gestation who required cEEG monitoring for clinical concerns were eligible, and were enrolled prospectively over 2 years from June 2013. Additional retrospective data were available from two centres for January 2011 to February 2014. Clinical data and EEGs were reviewed by expert neurophysiologists through a central server.

Results

Of 214 neonates who had recordings suitable for analysis, EEG seizures were confirmed in 75 (35%). The most common cause was hypoxic-ischaemic encephalopathy (44/75, 59%), followed by metabolic/genetic disorders (16/75, 21%) and stroke (10/75, 13%). The median number of seizures was 24 (IQR 9–51), and the median maximum hourly seizure burden in minutes per hour (MSB) was 21 min (IQR 11–32), with 21 (28%) having status epilepticus defined as MSB>30 min/hour. MSB developed later in neonates with a metabolic/genetic disorder. Over half (112/214, 52%) of the neonates were given at least one antiepileptic drug (AED) and both overtreatment and undertreatment was evident. When EEG monitoring was ongoing, 27 neonates (19%) with no electrographic seizures received AEDs. Fourteen neonates (19%) who did have electrographic seizures during cEEG monitoring did not receive an AED.

Conclusions

Our results show that even with access to cEEG monitoring, neonatal seizures are frequent, difficult to recognise and difficult to treat.

Oberservation study number

NCT02160171
Clinical relevance of protruded retinal layers in minimum rim width measurement of the optic nerve head
Authors: Torres Lucas A , Jarrar Faisal , Sharpe Glen P , Hutchison Donna M , Ferracioli-Oda Eduardo , Hatanaka Marcelo , Nicolela Marcelo T , Vianna Jayme R , Chauhan Balwantray C
Published: November 2018

Background/aims

Optical coherence tomography (OCT) imaging of the optic nerve head minimum rim width (MRW) has recently been shown to sometimes contain components besides extended retinal nerve fibre layer (RNFL). This study was conducted to determine whether excluding these components, termed protruded retinal layers (PRLs), from MRW increases diagnostic accuracy for detecting glaucoma.

Methods

In this cross-sectional study, we included 123 patients with glaucoma and 123 normal age-similar controls with OCT imaging of the optic nerve head (24 radial scans) and RNFL (circle scan). When present, PRLs were manually segmented, and adjusted MRW measurements were computed. We compared diagnostic accuracy of adjusted versus unadjusted MRW measurement. We also determined whether adjusted MRW correlates better with RNFL thickness compared with unadjusted MRW.

Results

The median (IQR) visual field mean deviation of patients and controls was −4.4 (−10.3 to −2.1) dB and 0.0 (−0.6 to 0.8) dB, respectively. In the 5904 individual B-scans, PRLs were identified less frequently in patients (448, 7.6%) compared with controls (728, 12.3%; p<0.01) and were present most frequently in the temporal sector of both groups. Areas under the receiver operating characteristic curves and sensitivity values at 95% specificity indicated that PRL adjustment did not improve diagnostic accuracy of MRW, globally or temporally. Furthermore, adjusting MRW for PRL did not improve its correlation with RNFL thickness in either group.

Conclusion

While layers besides the RNFL are sometimes included in OCT measurements of MRW, subtracting these layers does not impact clinical utility.
Effectiveness of implementation strategies for the improvement of guideline and protocol adherence in emergency care: a systematic review
Authors: Ebben Remco H A , Siqeca Flaka , Madsen Ulla Riis , Vloet Lilian C M , van Achterberg Theo
Published: November 2018

Objective

Guideline and protocol adherence in prehospital and in-hospital emergency departments (EDs) is suboptimal. Therefore, the objective of this systematic review was to identify effective strategies for improving guideline and protocol adherence in prehospital and ED settings.

Design

Systematic review.

Data sources

PubMed (including MEDLINE), CINAHL, EMBASE and Cochrane.

Methods

We selected (quasi) experimental studies published between 2004 and 2018 that used strategies to increase guideline and protocol adherence in prehospital and in-hospital emergency care. Pairs of two independent reviewers performed the selection process, quality assessment and data extraction.

Results

Eleven studies were included, nine of which were performed in the ED setting and two studies were performed in a combined prehospital and ED setting. For the ED setting, the studies indicated that educational strategies as sole intervention, and educational strategies in combination with audit and feedback, are probably effective in improving guideline adherence. Sole use of reminders in the ED setting also showed positive effects. The two studies in the combined prehospital and ED setting showed similar results for the sole use of educational interventions.

Conclusions

Our review does not allow firm conclusion on how to promote guideline and protocol adherence in prehospital emergency care, or the combination of prehospital and ED care. For ED settings, the sole use of reminders or educational interventions and the use of multifaceted strategies of education combined with audit and feedback are all likely to be effective in improving guideline adherence.
Prognostic factors for recovery and non-recovery in patients with non-specific neck pain: a protocol for a systematic literature review
Authors: Domingues Lucia , Cruz Eduardo B , Pimentel-Santos Fernando M , Ramiro Sofia , Donato Helena , Manica Santiago Rodrigues , Hayden Jill Alison , Buchbinder Rachelle , Branco Jaime C
Published: November 2018

Introduction

Neck pain is a common musculoskeletal disorder worldwide. It can result in significant disability and impaired quality of life. More than 50% of patients with neck pain still report symptoms 1 year later despite receiving different forms of non-pharmacological and pharmacological treatment. Identifying patient characteristics that are modifiable or predict recovery and non-recovery for an individual patient might identify ways of improving outcomes. This systematic review aims to comprehensively summarise the existing evidence regarding baseline patient characteristics associated with recovery and non-recovery, as defined by measures of pain intensity, disability and global perceived improvement.

Methods and analysis

Six electronic databases, PubMed, CINAHL, PEDro Database, EMBASE, Cochrane Library and Web of Science, will be searched, with terms related to the review question such as neck pain, prognostic or predictive research, from inception to 28 September of 2018. Studies will be included if they have investigated an association between patient characteristics and outcomes, with at least one follow-up time point. Two independent reviewers will screen the titles and abstracts followed by a full-text review to assess papers regarding their eligibility. Data from included papers will be extracted using standardised forms, including study and participants’ characteristics, outcomes, prognostic factors and effect size of the association. The risk of bias of each study will be assessed using the Quality in Prognostic Studies tool. A narrative synthesis will be conducted considering the strength, consistency of results and the methodological quality.

Ethics and dissemination

This systematic review does not require ethical approval. The results will be disseminated through publication in a peer-review journal, as a chapter of a doctoral thesis and through presentations at national and international conferences.

PROSPERO registration number

CRD42018091183.
‘Primary care sensitive’ situations that result in an ambulance attendance: a conversation analytic study of UK emergency ‘999’ call recordings
Authors: Booker Matthew James , Shaw Ali R G , Purdy Sarah , Barnes Rebecca
Published: November 2018

Objectives

To explore common features of conversations occurring in a sample of emergency calls that result in an ambulance dispatch for a ‘primary care sensitive’ situation, and better understand the challenges of triaging this cohort.

Design

A qualitative study, applying conversation analytic methods to routinely recorded telephone calls made through the ‘999’ system for an emergency ambulance. Cases were identified by a primary care clinician, observing front-line UK ambulance service shifts. A sample of 48 ‘999’ recordings were analysed, corresponding to situations potentially amenable to primary care management.

Results

The analysis focuses on four recurring ways that speakers use talk in these calls. Progress can be impeded when call-taker’s questions appear to require callers to have access to knowledge that is not available to them. Accordingly, callers often provide personal accounts of observed events, which may be troublesome for call-takers to ‘code’ and triage. Certain question formats—notably ‘alternative question’ formats—appear particularly problematic. Callers deploy specific lexical, grammatical and prosodic resources to legitimise the contact as ‘urgent’, and ensure that their perception of risk is conveyed. Difficulties encountered in the triage exchange may be evidence of misalignment between organisational and caller perceptions of the ‘purpose’ of the questions.

Conclusions

Previous work has focused on exploring the presentation and triage of life-threatening medical emergencies. Meaningful insights into the challenges of EMS triage can also be gained by exploring calls for ‘primary care sensitive’ situations. The highly scripted triage process requires precise, ‘codeable’ responses to questions, which can create challenges when the exact urgency of the problem is unclear to both caller and call-taker. Calling on behalf of someone else may compound this complexity. The aetiology of some common interactional challenges may offer a useful frame for future comparison between calls for ‘primary care sensitive’ situations and life-threatening emergencies.
Experiences with approaches to advance care planning with older people: a qualitative study among Dutch general practitioners
Authors: Glaudemans Jolien Jeltje , Moll van Charante Eric , Wind Jan , Oosterink John Jacob , Willems Dick Ludolf
Published: November 2018

Objectives

Advance care planning (ACP) with older people needs to be approached differently than ACP with patients with a terminal illness. ACP is still used with only a minority of older patients due to a lack of knowledge regarding appropriate approaches to ACP with older people. General practitioners (GPs) may play a key role in ACP with older people. Therefore, we explored their experiences with and views on approaches to ACP with older patients in daily practice.

Design, setting and participants

A qualitative study among a purposive sample of 19 Dutch GPs based on semistructured interviews.

Results

Approaches to ACP with older patients can be divided into two categories: systematic and ad hoc. Systematic approaches consisted of discussing a fixed combination of topics with community-dwelling older patients who are frail, cognitively impaired or are aged >75 years, and with older patients living in residential care homes during group information meetings, intakes, comprehensive geriatric assessments and periodic assessments. Meetings were aimed at making agreements in anticipation of future care, at providing information and encouraging older people to take further steps in ACP. With ad hoc approaches, respondents discussed only one or two topics related to the near future. Ad hoc ACP was mainly done with deteriorating patients or when patients or family initiated ACP. Systematic and ad hoc approaches were used simultaneously or sequentially and were both used for initiating and following up on ACP. Due to a lack of time and knowledge of other occasions and topics than the ones respondents used, respondents seemed to underuse many occasions and topics.

Conclusions

Awareness of appropriate systematic and ad hoc approaches for ACP, and the focus on providing information and encouraging older people to take further steps in ACP reported in this study can support GPs and improve older patients’ access to ACP.
How do palliative care doctors recognise imminently dying patients? A judgement analysis
Authors: White Nicola , Harries Priscilla , Harris Adam JL , Vickerstaff Victoria , Lodge Philip , McGowan Catherine , Minton Ollie , Tomlinson Christopher , Tookman Adrian , Reid Fiona , Stone Patrick
Published: November 2018

Objectives

To identify a group of palliative care doctors who perform well on a prognostic test and to understand how they make their survival predictions.

Design

Prospective observational study and two cross-sectional online studies.

Setting

Phase I: an online prognostic test, developed from a prospective observational study of patients referred to palliative care. Phase II: an online judgement task consisting of 50 hypothetical vignettes.

Participants

All members of the Association of Palliative Medicine (APM) were eligible (n=~1100). 99 doctors completed the prognostic test and were included in the phase I analysis. The top 20% were invited to participate in phase II; 14/19 doctors completed the judgement task and were included in the phase II analysis.

Measures

Phase I: participants were asked to give a probability of death within 72 hours (0%–100%) for all 20 cases. Accuracy on the prognostic test was measured with the Brier score which was used to identify the ‘expert’ group (scale range: 0 (expert)–1 (non-expert)). Phase II: participants gave a probability of death within 72 hours (0%–100%). A mixed model regression analysis was completed using the percentage estimate as the outcome and the patient information included in the vignettes as the predictors.

Results

The mean Brier score of all participants was 0.237 (95% CI 0.235 to 0.239). The mean Brier score of the ‘experts’ was 0.184 (95% CI 0.176 to 0.192). Six of the seven prognostic variables included in the hypothetical vignettes were significantly associated with clinician predictions of death. The Palliative Performance Score was identified as being the most influential in the doctors’ prognostic decision making (β=0.48, p<0.001).

Conclusions

This study identified six clinical signs and symptoms which influenced the judgement policies of palliative care doctors. These results may be used to teach novice doctors how to improve their prognostic skills.