bluuebunny/crossref_metadata_2025 huggingface dataset:
BRUTE: Evaluation of Mechanical Properties of True Reactor Pressure Vessel Material From Barsebäck 2
Authors: Arffman Pentti , Lydman Jari , Hytönen Noora , Que Zaiqing , Lindqvist Sebastian
Published: November 2022

Project BRUTE has investigated weld materials extracted from the decommissioned Barsebäck 2 reactor pressure vessel. The materials investigated originate from the pressure vessel head (RPVH) and beltline regions. The performed mechanical testing include tensile, Charpy impact and fracture toughness testing.

Tensile testing with miniature specimens demonstrates a difference of over 50 MPa in the yield and ultimate tensile strengths of the RPVH and beltline materials. Beltline specimens tested at the operating temperature exhibit discontinuity past the yield region, possibly indicating dynamic strain aging.

Charpy impact tests were performed around the transition region of the material. Transition curves were fitted, and reference temperatures T28J of −85 °C and −106 °C were determined for RPVH and beltline materials, respectively. This indicates better material properties at beltline compared to the RPVH, in agreement with tensile results. The reference temperatures T28J were further utilized to estimate brittle fracture initiation toughness reference temperatures T0.

Fracture toughness testing follows the Master Curve methodology defined in ASTM standard E1921. Reference temperatures T0 were determined at −115.1 °C and −101.1 °C for the RPVH and beltline, respectively, but the tests indicate inhomogeneity in both materials. The mean reference temperatures of the multimodal models TM were determined at −110.0 °C and −96.5 °C, and the associated, margin adjusted lower confidence bounds TM5%, MA at −13.3 °C and −53.0 °C for the RPVH and beltline materials, respectively. The latter values indicate that the inhomogeneity is more extensive in the RPVH. The estimates obtained from the Charpy impact toughness results do not correlate consistently with the fracture toughness-based transition temperature, possibly due to the inhomogeneity of the materials.

The results show that the safety of the materials can be assessed reliably, provided that contemporary methods, equipment and analyses are used.
FRACTESUS Project: Final Selection of RPV Materials for Unirradiated and Irradiated Round Robins
Authors: Brynk Tomasz , Uytdenhouwen Inge , Arffman Pentti , Altstadt Eberhard , Kopriva Radim , Obermeier Florian , Serrano Marta
Published: November 2022

The H2020 FRACTESUS project is aimed at the validation of miniaturized compact tension (MCT) specimen. More specifically the usage of the MCT with the Master Curve (MC) oriented fracture toughness testing of reactor pressure vessel (RPV) materials in hot cell conditions will be examined. In the first stage of the project, a general strategy of material selection and testing processes has been established. The choice of the selected RPV materials is based on the widest possible range of mechanical properties expected for baseline materials, but also resulting from their exposure to neutron irradiation, in terms of different MC reference temperature T0, and properties determined from Charpy impact testing. Moreover, in order to validate the use of the MCT in a broad application space, it was decided to perform FT tests for both base metals and welds. The largest challenge was related to the availability of those materials. They need to be tested in numerous, planned round robin exercises. They should have already an existing extensive database of fracture toughness results obtained using large specimens. The final version of the test matrix was prepared, keeping all those requirements in mind. An irradiated round robin exercise is planned for one type of weld material, namely 73W, that will be tested by seven partners. Additionally, the FRACTESUS partners were divided into smaller groups with 3–5 participants who will test a sub-selection of unirradiated materials in six round robin exercises. This paper presents the summary of the material selection activities in the FRACTESUS project. The materials are briefly described and rationale for their usage within the project is provided.
Root Cause Failure Investigation of MSCV Drain Failures
Authors: Jackson Peter , Wholey Alex , Tsai Eric , Burns Darby
Published: November 2022

Main Steam Stop and Control Valves (MSCVs) are safety critical components in modern steam power plants including large, combined cycle gas turbine (CCGT) plants. Repeated failures of the after seat drain piping at a dissimilar metal weld have occurred at one large CCGT that is regulated by the ISO in AGC and therefore experiences few startups.

This paper describes the results from a comprehensive evaluation of contributors to the repeated failures in one of two MSCV including: pipe stress analysis of the drain pipe layout, vibration testing of the MSCV and drain piping system using accelerometers and motion amplified video (MAV) technology and other inspections of the large bore pipe hanger system adjacent to the valves.

Forensic investigations by a metallographic laboratory were conducted which provide important conclusions about the root cause of the drain weld failures, material condition and heat treatment procedures. Additional calculations of transient thermal stress were also conducted in accordance with the guidance that is available in ASME Code Section III NB-3650 to address additional stress that is present due to transient temperature conditions at the failed DMW weld where a substantial geometric discontinuity is present between the drain pipe and the downstream forged block valve.

Results from plant operating data archives were used to establish process conditions during plant startup and indexing the measured vibration characteristics when the MSCV drains opened and closed. Field NDT (PMI, UT thickness testing) and hardness testing was used to confirm the material in the drain lines components which have not experienced failures.

Recommendations were developed from this program that identify the principal cause of the high level of vibration in the affected MSCV, the benefits of modifications to the drain system pipe materials, dimension and layout and the improvement of oversight of heat treatment of future repairs.
Friction Stir Welding of Hybrid Recycled Metal Matrix Composites
Authors: Christy John Victor , Ismail Mourad Abdel Hamid
Published: November 2022

In this work, conventional Friction Stir Welding (FSW) was used to investigate the weldability of recycled hybrid Aluminum Matrix Composites (AMCs). The novel composites were developed by squeeze stir casting process of scrap aluminum alloy wheels of cars as matrix and 4 wt.% of graphite, and 5 wt% of alumina as reinforcements. The casting parameters optimized from our previous work, such as squeeze pressure of 100 MPa, squeeze time of 45s, die preheating temperature of 250°C, and stirrer speed of 525 rpm, were used while casting the hybrid AMC rods. 4 mm plates were cut from each rod and subjected to an in-air friction stir welding process using a cylindrical tool of 16 mm diameter and 3 mm pin depth. Two-pass welding with a tool rotation of 1600 rpm and feed rates of 24 mm/min and 55 mm/min were used for FSW of samples. The welded section was cut out and subjected to mechanical tests such as tensile and Brinell hardness tests. It was observed that the samples welded at lower feed rates exhibited a higher tensile strength of 154 MPa and Brinell Hardness number of 61. The weldability of the recycled composites was successfully tested using FSW, a sustainable welding process. The work shows that hybrid recycled AMCs can be used for piping’s and structures prone to wear.
Specimen Size and Geometry Effects on the Master Curve Fracture Toughness Measurements of EUROFER97 and F82H Steels
Authors: Chen Xiang (Frank) , Sokolov Mikhail A. , Gonzalez De Vicente Sehila M. , Katoh Yutai
Published: November 2022

EUROFER97 and F82H are two leading reduced-activation ferritic-martensitic (RAFM) steels for fusion blanket applications. Exposure to the harsh environment of fusion reactors can result in severe degradation of materials fracture toughness (FT). Thus, the post-irradiation evaluation of FT is critical to understanding the material behavior. Due to the space constraint of irradiation facilities, the development of small specimen test techniques (SSTT) is necessary to evaluate the performance of irradiated materials. In this study, we evaluated the specimen size and geometry effects on the ductile-to-brittle transition FT of EUROFER97 batch-3 and F82H-BA12 steels. The specimen thicknesses ranged from 1.65 to 12.7 mm and the geometries included 1.65 mm bend bar, 4 mm mini-compact tension (miniCT), and 0.5T compact tension (CT) specimens. Fracture toughness testing and evaluations were performed using the Master Curve method in the ASTM E1921-19 standard. After size correction to 1T size using the Master Curve method, no specimen size effect was observed between the 4 mm miniCT and 0.5T CT specimens for the Master Curve reference temperature T0Q, while the bend bars yielded a higher T0Q. A strong effect of fatigue precrack front straightness on T0Q for 0.5T CT specimens was observed. The minimum number of specimens needed for each specimen geometry has been determined.
Dancing Manhole-Cover Basics
Authors: van de Meulenhof Niels F. , Tijsseling Arris S. , Vasconcelos Jose G.
Published: November 2022

A manhole is a shaft that functions as an access point to the underground infrastructure and is covered with a very heavy lid, sometimes weighing more than 100 kg. Occasionally a strange phenomenon occurs in which such a manhole cover is lifted above its opening and sort of dances on or above its supporting ring without any human intervention. This usually happens when it is stormy with heavy rainfall, but it is not tied to one specific location. Videos from all over the world can be found on the internet showing such ‘dancing manhole covers’. Sometimes air seems to be the main driving force behind the behavior, sometimes water, and sometimes both. Although the videos are funny, the behavior can create a very dangerous situation for both traffic and pedestrians. In this report the cause of these ‘dancing manhole covers’ is studied.

The ‘dancing’ is simplified into two different problems: one with an overflow of air and one with an overflow of water. For both problems a simple model consisting of differential equations is proposed and the numerical results are studied. The problem with an overflow of air is driven by an influx of air into the manhole from below, resulting in an increase in pressure, which lifts up the cover, until air is allowed to escape, and the pressure decreases again. Two different approaches for the escaping discharge of air are tried. The overflow of water is driven by a constant pressure that is exerted on a water column inside the manhole. Furthermore, a solution to the dancing problem is proposed: attaching the manhole cover to the ground with a hinge. This solution is tested by using a similar model as the one used for the overflow of air.
Research on the Laws of Soil Subsidence Range on the Response of Buried Pipelines
Authors: Xu Feng , Xu Yongsheng , Song Jianfei , Liu Cenfan , Liu Xin
Published: November 2022

In recent years, there have been frequent leakage and explosion accidents caused by the cracking of the circumferential weld of buried pipelines, and soil subsidence is one of the main reasons for the accidents. This paper carries out a numerical simulation analysis based on the soil spring model of the buried pipeline, and studies the mechanical response laws such as axial stress and deformation of buried pipelines under different subsidence ranges. The results show that: With the increases of the subsidence range, the deformation of the pipeline first gradually increases, and then remains unchanged, the axial stress of the pipeline, first increases, then decreases slightly, and finally remains unchanged. With the increase of soil subsidence amount, the dangerous subsidence range of soil increases. When the subsidence amount reaches the yield displacement of the soil, with the increase of subsidence range, the maximum axial stress of the pipeline increases. The results have certain guiding significance for the design and maintenance of buried pipelines.
Research on the Influence of Girth Weld Joint Matching Degree on the Safety Performance of High Steel Grade Pipeline Based on ASME Local Strain Limit Criterion
Authors: Liu Xin , Sun Liang , Xu Yongsheng , Wang Haitao , Deng Guide
Published: November 2022

In this study, numerical simulation is used to analyze the influence of the mechanical properties matching degree of weld, HAZ and base metal on the maximum axial strain of high steel grade pipeline. Based on ASME VIII-2 local strain limit criterion and cumulative damage model, the fracture process of girth weld structure under axial displacement and internal pressure is simulated with XFEM. The material parameters of base metal and weld which are necessary for the simulation calculation are obtained by monotonic tensile test, and the material parameters of HAZ are assumed to be lower than those of the weld and base metal to a certain extent. The results show that for different matching degree combinations, the crack initiation location always appears in the HAZ with the lowest mechanical properties, and the axial strain of the pipeline decreases with the increase of the internal pressure. For the undermatched girth weld, the lower the mechanical properties of the weld is, the smaller the maximum axial strain of the girth weld pipe is. For overmatched girth weld, when the internal pressure is less than 6 MPa, the maximum axial strain of 20% overmatched girth weld pipe is higher than that of 10% overmatched girth weld pipe. However, when the internal pressure is higher than 6 MPa, the maximum axial strain of 20% overmatched girth weld pipe is smaller.
3D Simulation of Propagation Induced by Primary Water Stress Corrosion Cracking for Defect Tolerance Analysis of Dissimilar Metal Welds
Authors: Dulieu Pierre , Lacroix Valéry
Published: November 2022

In the Belgian Pressurized Water Reactors Doel 3-4 and Tihange 2-3, the Reactor Pressure Vessel (RPV) nozzle-to-safe-end Dissimilar Metal butt Welds (DMW) are made of nickel-base alloy 182. This material is known to be susceptible to Primary Water Stress Corrosion Cracking (PWSCC) if the stress level is high enough. As a part of the prevention strategy, weld residual stresses have been assessed from experiments and numerical simulations. Moreover, a Defect Tolerance Analysis (DTA) is conducted to assess the acceptability of flaws that could possibly be detected during In-Service Inspection campaigns and to define reasonable inspection intervals. This analysis accounts for the plant specific residual stress profiles and operating loads to calculate the time for a postulated flaw to grow up to an acceptable size limit. Most of the time, the flaw propagation rate induced by PWSCC relies on stress intensity factors calculated in simplified geometries such as plates or pipes without accounting for the actual weld geometry. Therefore, 3D XFEM crack growth calculations are conducted considering more realistic hypotheses in order to quantify the level of conservatism of the simplified approach. The present paper focuses on the benefit of using detailed simulations of crack growth.
Combined Effect of Sustained Load and Harsh Environment on E-Glass/Epoxy Composites: Long Term Exposure
Authors: Idrisi Amir Hussain , Ismail Mourad Abdel Hamid
Published: November 2022

In this work, the durability of the E-glass/epoxy was investigated in terms of degradation in tensile properties and microstructure. Specimens were conditioned in seawater under sustained load and without load at 23 °C, 45 °C and 65 °C for the period of 15 months. The tensile strength of the E-glass/epoxy reduced gradually with immersion time. It reduced by 11% from 811 MPa to 721 MPa and by 18.2% from 811 MPa to 663 MPa for samples immersed without load and with 15% sustained load respectively. The respective reduction for 23°C and 45°C was 1.1% and 5.5% for samples without load and 6.2% and 11.3% for samples immersion under 15% sustained load after 15 months of exposure. The failure strain of E-glass/epoxy composite was slightly affected for the samples immersed without load during the period of 15 months but it was more noticeable under 15% sustained load at 65°C when the tensile strain reduced to 1.65% after 15 months of immersion. Furthermore, Scanning Electron Microscopy (SEM) analysis was conducted to evaluate the degradation of fiber matrix interface. Results revealed that moisture, temperature and sustained load have a deteriorative impact on the performance of the composite.
Crack Growth Simulation Using Iterative Crack-Tip Modeling Technique
Authors: Lee Gi-Bum , Jang Youn-Young , Huh Nam-Su , Park Sung-Hoon , Park Noh-Hwan , Park Jun , Park Kyoungsoo
Published: November 2022

Because of the long-term operation of nuclear power plants, the assessment of crack growth in pipelines has become one of the most important issues. Crack growth resistance in operating nuclear power plants is typically evaluated using linear elastic fracture mechanics based on ASME B&PV Section XI. However, the ASME method predicts the results conservatively, for complex shapes and conditions, while the finite element analysis, which is more accurate, consumes a substantial amount of time and cost. In this study, a finite element analysis-based iterative crack growth program was created to evaluate cracks with more accuracy and time efficiency. The verification of the program was carried out in two cases. By comparing the produced program with the test result of the three-point bending of the beam with rivet holes, it was shown that the program simulates crack propagation in the right direction. In addition, by comparing the results of the fatigue crack growth (FCG) test of CCT/SENT specimens, it was shown that the program can be applied to the evaluation of major failure mechanisms in the nuclear power plants such as stress corrosion crack (SCC) growth and FCG.
Probabilistic Control Rod Failure Analysis for a Nominal Molten Salt Reactor
Authors: Cathcart Henry , Finley James , Taylor John , Frost Alexander
Published: November 2022

Advanced Modular Reactors (AMRs) are expected to aid in the transition to net-zero emissions. In some candidate AMR concepts, a molten salt/fuel mixture passes through fuel channels in graphite bricks, while other bricks are reserved for the insertion of control rods. The neutron fluence in the reactor core displaces carbon atoms in the graphite, leading to a non-linear change in brick dimensions. This change in dimensions could, in certain circumstances, prevent the insertion of control rods and lead to reactor control failure. This paper explores how the exposure of graphite to radiation could lead to reactor control failure using both deterministic and probabilistic analyses. The deterministic approach determines the change in brick dimensions in a single channel using finite element analysis. Conversely, the probabilistic analysis uses a response surface surrogate Monte-Carlo analysis to predict the likelihood of reactor control failure for a single or multiple channels. The deterministic assessment indicates that reactor control failure is not likely. However, the probabilistic analysis shows that the epistemic and aleatory uncertainties in the reactor aggregate, leading to imperfect tessellation of the graphite bricks and a higher probability of failure. The probabilistic approach suggests that after 10 years, reactor control failure is likely in the outer core channels where the influence of imperfect tessellation is the strongest.
Use of Mini-CT Specimens for Fracture Toughness Characterization of Irradiated Highly Embrittled Weld
Authors: Sokolov Mikhail A.
Published: November 2022

In the 1990’s, the Heavy Section Steel Irradiation Program at the ORNL performed investigation of the shape of the fracture toughness master curve for reactor pressure vessel steel highly embrittled because of irradiation exposure. A radiation-sensitive reactor pressure vessel (RPV) weld with intentionally enhanced copper content, designated KS-01, has been characterized in terms of static initiation (KJc) and Charpy impact toughness in the unirradiated and irradiated conditions. The objective of this original project was to investigate the ability of highly embrittled material to maintain the shape of the unirradiated transition fracture toughness curve, as well as to examine the ability of the Charpy 41-J shift to predict the fracture toughness shift at such high level of embrittlement. Irradiation of this weld was performed at the University of Michigan Ford Reactor in the new HSSI irradiation-anneal-reirradiation (IAR) facility. Broken specimens from that project have been saved in ORNL storage. To verify applicability of Mini-CT specimens for fracture toughness characterization of RPV materials as part of the DOE Light Water Reactor Sustainability Program, Mini-CT specimens were machined from broken Charpy specimens and tested according to ASTM E1921 standard. As result of this study, the fracture toughness of this weld derived by testing Mini-CT specimens in the unirradiated and irradiated conditions is compared to previously reported fracture toughness derived by large number of conventional specimens.
Experience Measuring Acoustic Induced and Flow Induced Vibration in a Blowdown Type System
Authors: Middleton Chris , Eilers Daniel , Karczub Denis , Swindell Rob , Horder Nick , Izuchi Hisao , Mann J. Adin
Published: November 2022

Tests were performed on a mockup of a typical relief/blowdown system. The system consisted of an NPS6x8 pressure relief valve, an NPS12 tailpipe, and an NPS20 header. Small bore connections were installed in the tailpipe and header. Simple structures representing a valve mass and stiffness were attached to the small bore connections. Various industry standard tee connections between the tailpipe and header and the small-bore connections to the tailpipe and the header were studied. The goal of the testing program was to provide data to quantify the tee connection style, mitigation methods, and provide data for improvements and validation of Acoustic Induced Vibration (AIV) and Flow Induced Vibration (FIV) prediction and assessment methods. This paper describes the challenges with measuring the very high strain and vibration levels and the data processing used to extract meaningful data. The learnings about the shifting of internal acoustic modes, separating the contributions of AIV and FIV, and separating the contributions of pipe bending modes, higher order pipe modes, higher order acoustic modes, and acoustic/structural coincidence are also described. This work is connected to other presentations which focus on using the data to predict AIV and FIV in realistic blowdown systems.
Development of a Phased Array Ultrasonic System for Residual Stress Measurement in Welding and Additive Manufacturing
Authors: Javadi Yashar , Hutchison Alistair , Zimermann Rastislav , Lines David , Sweeney Nina E. , Vasilev Momchil , Mohseni Ehsan , Vithanage Randika K. W. , MacLeod Charles N. , Pierce Gareth , Mehnen Jorn , Gachagan Anthony
Published: November 2022

Residual Stress (RS) in engineering components can lead to unexpected and dangerous structural failures, and thus represent a significant challenge to quality assurance in both welding and metal additive manufacturing (AM) processes. The RS measurement using the ultrasonic method is based on the acoustoelasticity law, which states that the Time-of-Flight (ToF) of an ultrasonic wave is affected by the stress field. Longitudinal Critically Refracted (LCR) waves have the highest sensitivity to the stress in comparison with the other type of ultrasonic waves. However, they are also sensitive to the material texture which negatively affects the accuracy of the RS measurement. In this paper, a Phased Array Ultrasonic Testing (PAUT) system, rather than the single element transducers which are traditionally used in the LCR stress measurement technique, is innovatively used to enhance the accuracy of RS measurement. An experimental setup is developed that uses the PAUT to measure the ToFs in the weld, where the maximum amount of tensile RS is expected, and in the parent material, stress-free part. The ToF variations are then interpreted and analyzed to qualify the RS in the weld. The same measurement process is repeated for the Wire Arc Additive Manufacture (WAAM) components. Based on the results, some variations between different acoustic paths are measured which prove that the effect of the residual stress on the ultrasonic wave is detectable using the PAUT system.
Temperature study of atmospheric-pressure plasma-enhanced spatial ALD of Al2O3 using infrared and optical emission spectroscopy
Authors: Mione M. A. , Vandalon V. , Kessels W. M. M. , Roozeboom F.
Published: November 2022

Atmospheric-pressure plasma-enhanced spatial atomic layer deposition (PE-s-ALD) is considered a promising technique for high-throughput and low-temperature deposition of ultrathin films for applications where volume and costs are particularly relevant. The number of atmospheric-pressure PE-s-ALD processes developed so far is rather limited, and the fundamental aspects of their growth mechanisms are largely unexplored. This work presents a study of the atmospheric-pressure PE-s-ALD process of Al2O3 using trimethylaluminum [TMA, Al(CH3)3] and Ar–O2 plasma within the temperature range of 80–200 °C. Thin-film analysis revealed low impurity contents and a decreasing growth-per-cycle (GPC) with increasing temperature. The underlying chemistry of the process was studied with a combination of gas-phase infrared spectroscopy on the exhaust plasma gas and optical emission spectroscopy (OES) on the plasma zone. Among the chemical species formed in the plasma half-cycle, CO2, H2O, CH4, and CH2O were identified. The formation of these products confirms that the removal of CH3 ligands during the plasma half-cycle occurs through two reaction pathways that have a different temperature dependences: (i) combustion reactions initiated by O2 plasma species and leading to CO2 and H2O formation and (ii) thermal ALD-like reactions initiated by the H2O molecules formed in pathway (i) and resulting in CH4 production. With increasing temperature, the dehydroxylation of OH groups cause less TMA adsorption which leads to less CO2 and H2O from the combustion reactions in the plasma step. At the same time, the higher reactivity of H2O at higher temperatures initiates more thermal ALD-like reactions, thus producing relatively more CH4. The CH4 can also undergo further gas-phase reactions leading to the formation of CH2O as was theoretically predicted. Another observation is that O3, which is naturally produced in the atmospheric-pressure O2 plasma, decomposes at higher temperatures mainly due to an increase of gas-phase collisions. In addition to the new insights into the growth mechanism of atmospheric-pressure PE-s-ALD of Al2O3, this work presents a method to study both the surface chemistry during spatial ALD to further extend our fundamental understanding of the method.
Temperature dependence of on–off ratio and reverse recovery time in NiO/β-Ga2O3 heterojunction rectifiers
Authors: Li Jian-Sian , Chiang Chao-Ching , Xia Xinyi , Ren Fan , Pearton S. J.
Published: November 2022

The temperature-dependent behavior of on/off ratio and reverse recovery time in vertical heterojunction p-NiO/β n-Ga2O/n+ Ga2O3 rectifiers was investigated over the temperature range of 25–300 °C. The device characteristics in forward bias showed evidence of multiple current transport mechanisms and were found to be dependent on the applied bias voltages and temperatures. The on–off ratio decreased from 3 × 106 at 25 °C to 2.5 × 104 at 300 °C for switching to 100 V reverse bias. For 200 μm diameter rectifiers, the reverse recovery time of ∼21 ns was independent of temperature, with the Irr monotonically increasing from 15.1 mA at 25 °C to 25.6 mA at 250 °C and dropping at 300 °C. The dI/dt increased from 4.2 to 4.6 A/μs over this temperature range. The turn-on voltage decreased from 2.9 V at 25 °C to 1.7 V at 300 °C. The temperature coefficient of breakdown voltage was negative and does not support the presence of avalanche breakdown in NiO/β-Ga2O3 rectifiers. The energy loss during switching from 100 V was in the range 23–31 μJ over the temperature range investigated.
Backscattering by a tilted intermediate thickness cylindrical metal empty shell in water
Authors: Hall Bernard R. , Marston Philip L.
Published: November 2022

Backscattering by metal shells in water was investigated by Morse, Marston, and Kaduchak [J. Acoust Soc. Am. 103(2), 785–794 (1998)]. The evolution of the backscattering as a function of frequency and tilt angle, the “acoustic color,” depended on the shell's thickness. The present study concerns scattering by a shell with an intermediate thickness-to-radius ratio (0.106). The results include: (a) meridional rays associated with a supersonic antisymmetric guided wave cause a prominent tilt-angle dependent enhancement at frequencies above the coincidence frequency; (b) a subsonic guided wave is also prominent over a range of frequencies and tilt angles; and (c) meridional ray contributions are evident in the time-frequency-angle domain.
Insights into the evolution of enzymatic specificity and catalysis: From Asgard archaea to human adenylate kinases
Authors: Verma Apoorv , Åberg-Zingmark Emma , Sparrman Tobias , Mushtaq Ameeq Ul , Rogne Per , Grundström Christin , Berntsson Ronnie , Sauer Uwe H. , Backman Lars , Nam Kwangho , Sauer-Eriksson Elisabeth , Wolf-Watz Magnus
Published: November 2022

Enzymatic catalysis is critically dependent on selectivity, active site architecture, and dynamics. To contribute insights into the interplay of these properties, we established an approach with NMR, crystallography, and MD simulations focused on the ubiquitous phosphotransferase adenylate kinase (AK) isolated from
Odinarchaeota
(OdinAK).
Odinarchaeota
belongs to the Asgard archaeal phylum that is believed to be the closest known ancestor to eukaryotes. We show that OdinAK is a hyperthermophilic trimer that, contrary to other AK family members, can use all NTPs for its phosphorylation reaction. Crystallographic structures of OdinAK-NTP complexes revealed a universal NTP-binding motif, while
19
F NMR experiments uncovered a conserved and rate-limiting dynamic signature. As a consequence of trimerization, the active site of OdinAK was found to be lacking a critical catalytic residue and is therefore considered to be “atypical.” On the basis of discovered relationships with human monomeric homologs, our findings are discussed in terms of evolution of enzymatic substrate specificity and cold adaptation.
A genomic snapshot of demographic and cultural dynamism in Upper Mesopotamia during the Neolithic Transition
Authors: Altınışık N. Ezgi , Kazancı Duygu Deniz , Aydoğan Ayça , Gemici Hasan Can , Erdal Ömür Dilek , Sarıaltun Savaş , Vural Kıvılcım Başak , Koptekin Dilek , Gürün Kanat , Sağlıcan Ekin , Fernandes Daniel , Çakan Gökhan , Koruyucu Meliha Melis , Lagerholm Vendela Kempe , Karamurat Cansu , Özkan Mustafa , Kılınç Gülşah Merve , Sevkar Arda , Sürer Elif , Götherström Anders , Atakuman Çiğdem , Erdal Yılmaz Selim , Özer Füsun , Erim Özdoğan Aslı , Somel Mehmet
Published: November 2022

Upper Mesopotamia played a key role in the Neolithic Transition in Southwest Asia through marked innovations in symbolism, technology, and diet. We present 13 ancient genomes (c. 8500 to 7500 cal BCE) from Pre-Pottery Neolithic Çayönü in the Tigris basin together with bioarchaeological and material culture data. Our findings reveal that Çayönü was a genetically diverse population, carrying mixed ancestry from western and eastern Fertile Crescent, and that the community received immigrants. Our results further suggest that the community was organized along biological family lines. We document bodily interventions such as head shaping and cauterization among the individuals examined, reflecting Çayönü’s cultural ingenuity. Last, we identify Upper Mesopotamia as the likely source of eastern gene flow into Neolithic Anatolia, in line with material culture evidence. We hypothesize that Upper Mesopotamia’s cultural dynamism during the Neolithic Transition was the product not only of its fertile lands but also of its interregional demographic connections.
Design principles for heterointerfacial alloying kinetics at metallic anodes in rechargeable batteries
Authors: Zheng Jingxu , Deng Yue , Li Wenzao , Yin Jiefu , West Patrick J. , Tang Tian , Tong Xiao , Bock David C. , Jin Shuo , Zhao Qing , Garcia-Mendez Regina , Takeuchi Kenneth J. , Takeuchi Esther S. , Marschilok Amy C. , Archer Lynden A.
Published: November 2022

How surface chemistry influences reactions occurring thereupon has been a long-standing question of broad scientific and technological interest. Here, we consider the relation between the surface chemistry at interfaces and the reversibility of electrochemical transformations at rechargeable battery electrodes. Using Zn as a model system, we report that a moderate strength of chemical interaction between the deposit and the substrate—neither too weak nor too strong—enables highest reversibility and stability of the plating/stripping redox processes. Focused ion beam and electron microscopy were used to directly probe the morphology, chemistry, and crystallography of heterointerfaces of distinct natures. Analogous to the empirical Sabatier principle for chemical heterogeneous catalysis, our findings arise from competing interfacial processes. Using full batteries with stringent negative electrode–to–positive electrode capacity (N:P) ratios, we show that such knowledge provides a powerful tool for designing key materials in highly reversible battery systems based on Earth-abundant, low-cost metals such as Zn and Na.
Challenges implementing a carer support intervention within a national
stroke organisation: findings from the process evaluation of the OSCARSS
trial
Authors: Darley Sarah , Knowles Sarah , Woodward-Nutt Kate , Mitchell Claire , Grande Gunn , Ewing Gail , Rhodes Sarah , Bowen Audrey , Patchwood Emma
Published: November 2022

Objectives

To examine the implementation of an intervention to support informal
caregivers and to help understand findings from the Organising Support
for Carers of Stroke Survivors (OSCARSS) cluster randomised controlled
trial (cRCT).

Design

Longitudinal process evaluation using mixed methods. Normalisation
process theory informed data collection and provided a sensitising
framework for analysis.

Setting

Specialist stroke support services delivered primarily in the homes
of informal carers of stroke survivors.

Participants

OSCARSS cRCT participants including carers, staff, managers and
senior leaders.

Intervention

The Carer Support Needs Assessment Tool for Stroke (CSNAT-Stroke)
intervention is a staff-facilitated, carer-led approach to help
identify, prioritise and address support needs.

Results

We conducted qualitative interviews with: OSCARSS cRCT carer
participants (11 intervention, 10 control), staff (12 intervention, 8
control) and managers and senior leaders (11); and obtained 140
responses to an online staff survey over three separate time points.
Both individual (carer/staff) and organisational factors impacted
implementation of the CSNAT-Stroke intervention and how it was received
by carers. We identified four themes: staff understanding, carer
participation, implementation, and learning and support. Staff valued
the idea of a structured approach to supporting carers, but key elements
of the intervention were not routinely delivered. Carers did not
necessarily identify as ‘carers’, which made it difficult for staff to
engage them in the intervention. Despite organisational enthusiasm for
OSCARSS, staff in the intervention arm perceived support and training
for implementation of CSNAT-Stroke as delivered primarily by the
research team, with few opportunities for shared learning across the
organisation.

Conclusions

We identified challenges across carer, staff and organisation levels
that help explain the OSCARSS cRCT outcome. Ensuring training is
translated into practice and ongoing organisational support would be
required for full implementation of this type of intervention, with
emphasis on the carer-led aspects, including supporting carer
self-identification.

Trial registration number

NCT58414120.
Multicentre, randomised trial of preterm infants receiving caffeine and less invasive surfactant administration compared with caffeine and early continuous positive airway pressure (CaLI trial): study protocol
Authors: Ines Felix , Hutson Shandee , Coughlin Katherine , Hopper Andrew , Banerji Anamika , Uy Cherry , Finer Neil , Rich Wade , Morales Ana , Steen Jane , Katheria Anup C
Published: November 2022

Introduction

Respiratory distress syndrome (RDS) or surfactant deficiency occurs primarily in premature infants resulting in composite outcomes of death or bronchopulmonary dysplasia. Initial management strategies for preterm infants with RDS includes early initiation of continuous positive airway pressure (CPAP) and titration of fractional inspired oxygen (FiO
2
), and may include the use of less invasive surfactant administration (LISA) to avoid the need for mechanical ventilation. In order to optimise success of non-invasive support, the use of early caffeine therapy may be critical to the success of LISA. The objective of our trial is to evaluate whether infants that receive early caffeine, CPAP and surfactant via the LISA method compared with infants that receive caffeine and CPAP alone, have a decreased need for invasive mechanical ventilation in the first 72 hours of life.

Methods and analysis

CaLI is an unblinded multicentre, randomised controlled, trial of 180 preterm infants (24+0–29+6 weeks corrected GA). Criteria for intubation/treatment failure will follow guidelines for the management of RDS, including: (1) CPAP level of 6–8 cmH20 and FiO
2
>0.40 required to maintain saturations 90%–95% for 2 hours after randomisation; (2) a pH of 7.15 or less or a paCO
2
>65 mm Hg on any (2) blood gases (arterial/capillary/or venous) at least 2 hours after randomisation and in the first 72 hours of life; (3) continued apnoea/bradycardia/desaturation events despite nasal intermittent minute ventilation mode of ventilation. Infants will be randomised by 1 hour of life and caffeine/LISA treatments administered by 2 hour of life. Caffeine will be administered prior to surfactant in the LISA arm and before 2 hours of life in the control arm.

Ethics and dissemination

Chiesi Farmaceutici, S.p.A is the sponsor of CaLI. Ethical approval has been obtained. Results will be submitted for publication in peer reviewed journals.

Trial registration number

www.Clinicaltrials.gov
:
NCT04209946; Pre-results
.
Is the Thoughts and Health programme feasible in the context of Swedish
schools? A quasi-experimental controlled trial study protocol
Authors: Wikberg Carl , Augustsson Pia , Sveinsdottir Gudny , Craighead W Edward , Arnarson Erikur Örn , Marteinsdottir Ina , Lilja Josefine L
Published: November 2022

Introduction

Clinical depression is a substantial problem among adolescents,
increasing significantly at about age 15 years. It causes impairment in
social, academic and familial relationships, as well as ongoing
cognitive and emotional difficulties for the individual. A study in
Iceland demonstrated that a cognitive–behavioural, developmentally based
intervention programme, ‘Thoughts and Health’, prevented initial
episodes of depression and/or dysthymia (DYS) (major depressive
disorder/DYS) in adolescents for up to 12 months following completion of
the programme. We would like to test the feasibility of implementing the
Icelandic method in a Swedish context and to evaluate the long-term
effects of such a programme.

Methods and analysis

A quasi-experimental controlled design, combined with qualitative
and quantitative methods, will be used to address the research
questions.

In this study, 617 children aged ~14 years will be screened for
depression, and those “at risk” for development of clinical depression
will be offered a 12 week course, ‘Thoughts and Health’. This course
aims to prevent first depression in adolescents. A comparable group of
children will function as controls.

Depending on the type of variable, baseline comparisons between the
two groups of relevant initial measures will be evaluated with t-tests
or χ2analyses. The effects of the programme on the
development of clinical levels of depression will be evaluated using the
follow-up data of 6, 12 and 18 months. Index parental depression at
baseline will be tested as a moderator in the evaluation of the effects
of the prevention programme.

Ethics and dissemination

This study is approved by the Swedish Ethical Review Board
(reference number 2019–03347) in Gothenburg.

We plan to disseminate the knowledge gained from this study by
publishing our results in peer-reviewed scientific journals and other
scholarly outlets.

Trial registration number

NCT04128644; Pre-results.
Population differences in vaccine responses (POPVAC): scientific
rationale and cross-cutting analyses for three linked, randomised controlled
trials assessing the role, reversibility and mediators of immunomodulation
by chronic infections in the tropics
Authors: Nkurunungi Gyaviira , Zirimenya Ludoviko , Natukunda Agnes , Nassuuna Jacent , Oduru Gloria , Ninsiima Caroline , Zziwa Christopher , Akello Florence , Kizindo Robert , Akello Mirriam , Kaleebu Pontiano , Wajja Anne , Luzze Henry , Cose Stephen , Webb Emily , Elliott Alison M
Published: November 2022

Introduction

Vaccine-specific immune responses vary between populations and are
often impaired in low income, rural settings. Drivers of these
differences are not fully elucidated, hampering identification of
strategies for optimising vaccine effectiveness. We hypothesise that
urban–rural (and regional and international) differences in vaccine
responses are mediated to an important extent by differential exposure
to chronic infections, particularly parasitic infections.

Methods and analysis

Three related trials sharing core elements of study design and
procedures (allowing comparison of outcomes across the trials) will test
the effects of (1) individually randomised intervention against
schistosomiasis (trial A) and malaria (trial B), and (2) Bacillus
Calmette-Guérin (BCG) revaccination (trial C), on a common set of
vaccine responses. We will enrol adolescents from Ugandan schools in
rural high-schistosomiasis (trial A) and rural high-malaria (trial B)
settings and from an established urban birth cohort (trial C). All
participants will receive BCG on day ‘0’; yellow fever, oral typhoid and
human papilloma virus (HPV) vaccines at week 4; and HPV and
tetanus/diphtheria booster vaccine at week 28. Primary outcomes are
BCG-specific IFN-γ responses (8 weeks after BCG) and for other vaccines,
antibody responses to key vaccine antigens at 4 weeks after
immunisation. Secondary analyses will determine effects of interventions
on correlates of protective immunity, vaccine response waning, priming
versus boosting immunisations, and parasite infection status and
intensity. Overarching analyses will compare outcomes between the three
trial settings. Sample archives will offer opportunities for exploratory
evaluation of the role of immunological and ‘trans-kingdom’ mediators in
parasite modulation of vaccine-specific responses.

Ethics and dissemination

Ethics approval has been obtained from relevant Ugandan and UK
ethics committees. Results will be shared with Uganda Ministry of
Health, relevant district councils, community leaders and study
participants. Further dissemination will be done through conference
proceedings and publications.

Trial registration numbers

NCT60517191,NCT62041885,NCT10482904.
Complex interventions to implement a diabetic retinopathy care pathway in
the public health system in Kerala: the Nayanamritham study protocol
Authors: Sivaprasad Sobha , Netuveli Gopalakrishnan , Wittenberg Raphael , Khobragade Rajan , Sadanandan Rajeev , Gopal Bipin , Premnazir Lakshmi , Conroy Dolores , Srinath Jyotsna , Ramakrishnan Radha , George Simon , Sahasranamam Vasudeva Iyer
Published: November 2022

Introduction

Using a type 2 hybrid effectiveness-implementation design, we aim to
pilot a diabetic retinopathy (DR) care pathway in the public health
system in Kerala to understand how it can be scaled up to and sustained
in the whole state.

Methods and analysis

Currently, there is no systematic DR screening programme in Kerala.
Our intervention is a teleophthalmology pathway for people with diabetes
in the non-communicable disease registers in 16 family health centres.
The planned implementation strategy of the pathway will be developed
based on the discrete Expert Recommendations for Implementing Change
taxonomy. We will use both quantitative data from a cross-sectional
study and qualitative data obtained from structured interviews, surveys
and group discussions with stakeholders to report the effectiveness of
the DR care pathway and evaluation of the implementation
strategy.

We will use logistic regression models to assess crude associations
DR and sight-threatening diabetic retinopathy and fractional polynomials
to account for the form of continuous covariates to predict uptake of DR
screening. The primary effectiveness outcome is the proportion of
patients in the non-communicable disease register with diabetes screened
for DR over 12 months. Other outcomes include cost-effectiveness,
safety, efficiency, patient satisfaction, timeliness and equity. The
outcomes of evaluation of the implementation strategies include
acceptability, feasibility, adoption, appropriateness, fidelity,
penetration, costs and sustainability. Addition of more family health
centres during the staggered initial phase of the programme will be
considered as a sign of acceptability and feasibility. In the long term,
the state-wide adoption of the DR care pathway will be considered as a
successful outcome of the Nayanamritham study.

Ethics and dissemination

The study was approved by Indian Medical Research Council
(2018-0551) dated 13 March 2019. Study findings will be disseminated
through scientific publications and the report will inform adoption of
the DR care pathway by Kerala state in future.

Trial registration number

NCT28942696.