bluuebunny/crossref_metadata_2025 huggingface dataset:
Verification of the RMC-SaraGR Nuclear Design Code System Based on the HTTR Benchmark
Authors: Yuan Yuan , Liu Guoming , Zhang Peng
Published: November 2024

In order to perform a detailed nuclear analysis for the small modular prismatic HTGRs, the RMC-SaraGR nuclear design code system has been developed. The verification of the code system using the HTTR benchmark is reported in this paper. The detailed HTTR models have been established with the continuous-energy Monte Carlo code RMC to provide the reference solutions and the 25-group cross sections, which are further corrected by the super homogenization (SPH) factors before being used for the homogeneous core transport calculations by SaraGR or the multi-group RMC (RMC-MG). Various core configurations including fully-loaded core with/without control rods (CRs) insertion and annular cores with different number of fuel columns loaded have been modeled. Compared with the benchmark data, the reference solutions provided by RMC show a 100∼ 500 pcm overestimation of keff for the fully-loaded cores, which may be attributed to the nuclear data uncertainty and the model bias. When the CR block is homogenized as a whole region, the calculation results from RMC-MG and SaraGR agree well but both show a significant keff overestimation of more than 1000 pcm compared with the RMC reference solution for the fully-loaded core with all CRs withdrawn, which is likely to be related to the strong neutron streaming effect through the void holes of the CR blocks. Therefore, a local mesh refinement is imposed on the CR blocks for an explicit modeling of the CR holes, which reduces the keff discrepancy to less than 500 pcm. Most results agree well with the reference solutions and are within an uncertainty of the benchmark values, indicating that the RMC-SaraGR code system is a feasible tool for the nuclear analysis of the prismatic HTGRs.
Human Reliability Analysis for a Passive NPP and Application in Plant Operating Procedure Optimization
Authors: Qiu Yongping , Tan Xiao
Published: November 2024

Human Reliability Analysis (HRA) is an important element in probabilistic safety assessment (PSA) for nuclear power plants (NPPs). Usually three types of human interactions (HIs) are defined in HRA for NPPs, i.e., pre-initiating event HIs, initiating event-related HIs, and post-initiating event HIs. In this paper, a brief introduction of the HRA methodology for a passive NPP is first presented. Then based on the HRA/PSA results and insights, design improvements and PSA applications could be performed. The optimization of plant operating procedures is one of the PSA applications in plant design phase. The risk-important human actions are obtained from the PSA importance analysis. Next, two risk-important human actions related to SGTR accident are studied in detail with the human error probability versus the design of plant operating procedures. Based on the sensitivity analysis, the operator response time for these two events, which varies with the steps of plant operating procedures, has certain influence on the plant core damage frequency (CDF) and rather high impact on the ratio of CDF variation of SGTR accident. Finally some proposals for optimization of the SGTR event analysis and relevant procedure steps are discussed. The plant operating procedures of the passive NPP are still under developing and optimization, and the study provides a useful way for plant operating procedure optimization.
Numerical Simulation of the Difference Between Steam-Seawater Jet and Steam-Freshwater Jet
Authors: Cao An , Niu Shipeng , Li Jianfa , Hua Yongzhen , Qi Xiangjie , Xiao Jiayu , Meng Zhaoming
Published: November 2024

The seawater reserves on the earth are much larger than freshwater, and the use of seawater instead of freshwater as the cooling medium for steam jet condensation can greatly alleviate the shortage of freshwater resources. However, current research on steam-water jet condensation mainly focuses on freshwater jet, with very few studies on seawater jet. In this paper, the software Fluent was used to compare and analyze the differences in the shape of stable jet condensation plumes, plume penetration length, pressure gradient, and velocity distribution between seawater and freshwater. The results show that the shape and pressure gradient of the steam plume in seawater are similar to those in freshwater, while the plume penetration length and axial velocity are slightly smaller than those in freshwater. Seawater has the feasibility of replacing freshwater as the cooling medium for suppression pool.
Study on Bubble Migration Characteristics in a Lead-Cooled Fast Reactor After Steam Generator Tube Rupture Accident
Authors: Feng Zhenyu , Zhang Dalin , Jiao Haoyu , Chen Yutong , Lin Yue , Tian Wenxi , Qiu Suizheng , Su Guanghui
Published: November 2024

In this paper, the bubble migration characteristics of LFR after SGTR accidents are investigated based on the DPM. Firstly, the geometric and mesh models of the primary coolant system of the LFR are established, and the drag coefficient model of bubbles in the DPM is validated based on the bubble terminal velocities. Secondly, steady-state simulation of the primary coolant system of the LFR are performed to determine the temperature and velocity fields. Thirdly, the migration characteristics of the single bubble released from different positions of the SG are investigated, and the results show that bubbles on the horizontal plane at the window position were more easily entrained away from the window side, while those on the horizontal plane below the window were more easily entrained near the window side. Finally, the bubble groups with different diameters and different positions are studied. Bubbles larger than 0.3 mm leaking at any position of the SG cannot be entrained into the core, and bubbles larger than 0.45 mm will escape directly. Additionally, the higher the location of the rupture the lower the probability of bubbles entering the core.
Hydrogen Production by High Temperature Steam Electrolysis Coupled With a Small Modular Reactor: Cross-Comparison Between Various Thermal Architectures
Authors: Tauveron Nicolas , Haubensack David , Dumoulin Pierre , Alpy Nicolas
Published: November 2024

This paper is part of a study on the coupling of a SMR nuclear unit to a hydrogen production process using high-temperature steam electrolysis (HTSE). Different possible coupling architectures are investigated and their energetic evaluation are performed. A numerical design of experiment is established in order to study the separate effects of the various architectural options envisaged in relation to a reference simulation configuration: with or without thermal coupling, direct or indirect steam supply, location of the extraction point in the SMR Rankine cycle, one-way or two-ways thermal coupling, internal heat recovery in the HTSE, and oxygen content.

The results obtained on the reference simulation configuration show that it is possible to obtain a gain of over 13% compared with the solution involving no thermal coupling between the SMR and the HTSE process (i.e. when HTSE heat is provided through electrical heaters), with a deviation of 3% from an idealized configuration with freely available heat and no utilization constraints (“ideal waste heat configuration”). It even outperforms the heat pump solution by more than 4%.

From a purely energetic point of view, and considering only the HTSE operating at atmospheric pressure, it can be seen that each optimized configuration deviates rather slightly from the reference simulation configuration: all energy performances enable gains of around 13% compared with the configuration with no thermal coupling between the SMR and the HTSE process. The solution with two-ways thermal coupling is also more efficient than the one-way coupling.
Enhancing Hydrogen Laminar Burning Velocity Estimation With Artificial Neural Networks and Simulated Data
Authors: Ambrutis Andrius , Povilaitis Mantas
Published: November 2024

Practically relevant containment scale combustion simulations require fast methods applicable to comparatively sparse meshes, e.g. RANS. Combustion rate in this case can be estimated using simplified progress variable equation closures, for example, Turbulent Flame speed Closure model, and correlations for laminar burning velocity (LBV) instead of chemical kinetics. However, existing correlations may lack accuracy and have restricted validity domains. In the previous work, by developing experimental-data-based Artificial Neural Networks (ANN) model (original), we showed that ANN can be used for fast and accurate prediction of LBV in dry hydrogen-air mixtures from temperature, pressure and equivalence ratio. However, due to limited amount of experimental data available in the literature, database consisted of a relatively low number of experimental datapoints (around 2000). This led to model exhibiting some unphysical behaviour at higher temperatures and specific pressures, requiring more data than is available to enhance its reliability. This work presents an attempt to solve the problem of insufficient database by replacing simulated data instead of experimental. The architecture of new ANN was kept similar to original ANN, ensuring similar prediction time. Instead of a few thousand experimental data points, new model was trained using around 1 000 000 data values generated using chemical kinetics simulation. The larger database improved new model predictions compared to original and led to a more physical LBV behaviour estimation. In addition, new model has an expanded range of applicability. In our estimation, any further improvement in our model accuracy is mostly limited by the number of neurons, restricted by the need for fast ANN calculations.
Designing a Knowledge-Centric Plant Information Model by Integrating Tacit Knowledge
Authors: Mosler Pascal , Rüppel Uwe
Published: November 2024

In knowledge-centric plant information models (K-PIMs) for nuclear power plants, the focus is not on documents or data, but on knowledge. Since knowledge is much more difficult to document and transfer than data and information, the design of a K-PIM requires a new approach and a rethinking of existing routines and processes. First, this paper identifies the technological and organizational requirements for a K-PIM. Two particular anchor points here are tacit knowledge in the context of knowledge management as well as the decommissioning phase. The effects of knowledge gaps and inadequate knowledge management become clear in the decommissioning phase at the latest and are expressed in additional work for data collection and in the question of how to deal with legacy data. For this reason, the approach chosen here is to think about the requirements for a K-PIM “from the end”, i.e. from decommissioning and the explicit and tacit knowledge required there. Although tacit knowledge plays a significant role in routine operation, it is currently only inadequately mapped in information models and is difficult to access for other people, not to mention future generations. Based on these findings, a K-PIM is proposed in which knowledge is spatially located and can therefore be experienced holistically. Three technologies play a central role in the proposed concept: building information modeling, extended reality (including virtual reality and augmented reality), and semantic technologies. Together, they create a possible basis for the successful incorporation and transfer of both explicit and implicit knowledge.
Study of Jet Characteristics and Structural Fatigue in the Upper Chamber of a Lead-Bismuth Eutectic Cooled Reactor Based on Fluid-Structure Coupling Methods
Authors: Zhang Ji , Wang Mingjun , Tian Wenxi , Qiu Suizheng , Su Guanghui
Published: November 2024

To evaluate the impact of temperature fluctuations caused by jet mixing in the upper plenum of a lead-bismuth eutectic (LBE) reactor on the fatigue damage of internal structural components, this paper conducts a study on the stress distribution of the operation head and the central column based on a fluid-solid coupling calculation method. On this basis, a fatigue damage assessment method under thermal stress for the solid domain is established. The fatigue damage of the operation head and the central column under typical working conditions, as well as the influence of the flow parameters at the operation head inlet on fatigue damage, are analyzed. The results indicate that the fatigue damage at the monitoring points on the side of the operation head is significantly higher than that in the central column and should be given special attention. Compared to velocity, fatigue damage is more sensitive to temperature distribution, and the degree of fatigue damage decreases with the reduction of temperature difference. The research in this paper can provide reference and guidance for the design and operation of LBE reactors.
Analysis and Research on Control Strategy of Supercritical Carbon Dioxide Recompression System
Authors: Liu Xiuting , Huang Yanping , Zhou Yuan , Liu Minyun , Yang Jun , Qin Bitan , Liu Ruilong
Published: November 2024

This article takes the supercritical carbon dioxide recompression cycle system as the research object, and analyzes different control methods such as speed control (including compressor speed regulation and turbine speed regulation), volume control (including changing compressor inlet pressure and compressor inlet temperature), and throttling control under established thermodynamic parameters. Based on the characteristics of the cycle and the characteristics of a single control method, a control strategy combining multiple control methods with different load intervals and mobility requirements is proposed. The research results indicate that speed control has the highest efficiency under partial load conditions among various methods, followed by volume control and throttling control. There are depth limits for load reduction in a single control method, and compressor surge and outlet pressure over pressure may occur in different load ranges. Based on the characteristics of different load intervals and regulation methods, we propose a combination control strategy scheme. When 0% FP ≤ load level < 20% FP, a combined control scheme of throttling control and bypass control is adopted; When 20% FP ≤ load level < 90% FP, the most efficient speed control scheme is adopted, which adopts speed gear adjustment to avoid frequent equipment actions. When 90% FP ≤ load level ≤ 100% FP, volume control is adopted.
Digital Twin and Surrogate Model for Long-Term Geochemical Processes in Nuclear Waste Management
Authors: Hu Guang , Miron George Dan , Pfingsten Wilfried , Dähn Rainer
Published: November 2024

This study presents an advance in predicting long-term stability in waste containment systems. Employing a surrogate model based on the 25 GEMS Python scripts, we simulate geochemical interactions within waste degradation processes over 100 years. The model simplifies complex full-scale geochemical models using a mixing tank approach, primarily examining the evolution of material properties influenced by uncertain surface characteristics and reaction kinetics. 1 million cases are generated using the neural network-based surrogate model, drastically reducing computational time (∼1.9 seconds) compared to traditional methods (∼78.4 days). The model evaluates the deterioration mechanisms of various materials like iron, aluminum, zinc, and brass, in cementitious waste packages, crucial for assessing their impact on the integrity of waste containment over extended periods.

Our findings with the neural network-based surrogate model, including ion concentrations and mass changes in materials like iron, brass, aluminum, and copper, offer detailed insights into chemical changes in the system. Incorporating a sensitivity analysis with 1 million cases generated by the surrogate model, the study underscores the interplay between chemical reactions and material properties, establishing a digital twin that links reaction rates to the stability of nuclear waste repositories. This study presents key indicators of potential integrity threats due to material expansion, contraction, or gas-induced pressure variations.
Visual Analysis of the Research Status, Hotspots, and Trends of International Nuclear Industry Internet Platforms
Authors: Xianying Liu , Jing Yinggang , Cheng Minmin , Fang Huajian
Published: November 2024

The Industrial Internet can improve the production efficiency of the energy industry through technologies such as intelligent control technology, remote monitoring technology, predictive maintenance technology, intelligent risk management and system security control, and is the core of promoting efficient allocation of manufacturing resources. As an important part of the energy field, nuclear power has higher requirements on safety and energy utilization than other conventional energy sources. Nuclear energy enterprises also need to rely on intelligent information management systems to improve the efficiency and safety of nuclear power production.

This article uses bibliometrics, combined with visual charts, to comparatively analyze the current situation, hot spots, and trends in the use of industrial Internet platform technology in the field of nuclear energy in major nuclear power countries, and combines the future development trends of international nuclear energy with the construction of industrial Internet platforms for nuclear power enterprises in the field of nuclear energy, planning, and provide brief reference suggestions.
General Outline of the Decommissioning of the Prototype Fast Breeder Reactor MONJU
Authors: Kobayashi Hideharu , Naruse Keiji , Hirako Kazuhito , Sawazaki Hiromasa , Goto Takehiro , Obata Ikuhito , Matsui Kazuaki
Published: November 2024

The prototype fast breeder reactor “MONJU” is a loop-type sodium-cooled nuclear reactor under decommissioning in Japan. Japan Atomic Energy Agency (JAEA) started its decommissioning in 2018, and will complete the four phases of decommissioning in about 30 years.

The phase I is already over. It was the “Fuel unloading” stage during which secondary sodium was drained, the fuel assemblies in the reactor core were removed and put in storage in the spent fuel pool, while the distribution of radioactive contamination in buildings, components, equipment, etc. was evaluated.

The phase II is ongoing. It is focused on the “Preparation for dismantling the plant”. We have been removing the neutron shields in the reactor core and putting them in storage in the spent fuel pool in preparation for the dismantling of the sodium-adhered equipment. We will also transport sodium, dismantle and remove the power-generating facility such as water/steam systems. In addition, we continue to assess the distribution of radioactive contamination in buildings, components, equipment, etc.

The phase III will be started in 2032. This phase, the “Decommissioning Period I” is focused on the dismantling and removing of sodium-adhered equipment, the transport of spent fuel, and the removal of the water and steam power generation system.

The final Phase is the “Decommissioning Period II” during which the radiation-controlled area will be lifted and all the buildings will be dismantled and removed.

This paper presents an overview of MONJU decommissioning, the results of the phase I, and details of the phase II currently ongoing.
Uncertainty and Sensitivity Analysis of Phebus FPT-1 Experiment Based on Severe Accident Analysis Code ISAA
Authors: Yang Hao , Zhang Bin , Li Jishen , Gao Pengcheng , Zhang Zhiran , Miao Fan
Published: November 2024

Since the Three Mile Island nuclear accident, international research on severe accidents has advanced through a combination of experimental studies and numerical simulations. The intricate physical processes and chemical phenomena involved in severe reactor accidents have led to a heavy reliance on empirical parameters in existing severe accident analysis programs, generating significant uncertainties. As a result, there is growing interest in applying systematic analysis programs combined with uncertainty quantification methods to evaluate potential severe accident consequences, a topic receiving considerable attention among researchers in severe accident analysis. In 2019, Europe initiated the MUSA project, an international collaboration focusing on severe accident management and uncertainty. The project centers on a series of severe accident uncertainty analysis studies based on the Phebus FPT1 experiment. This serves as a valuable tool for assessing severe accident analysis code effectiveness in simulating severe reactor accident progression and offers an opportunity to analyze and enhance code physical models. Previous numerical analysis studies using the integrated severe accident analysis program ISAA for the FPT experiment revealed the necessity for significant estimations, particularly in core degradation and source term release. This underscores the importance of conducting uncertainty and sensitivity studies on parameters affecting numerical simulation results using advanced uncertainty analysis methods. In this study, we employed a self-developed uncertainty analysis tool to conduct random sampling analysis based on Latin hypercube sampling for various uncertainty parameters, including experimental modeling data and code model parameters. Utilizing the Wilks theory, the study conducted uncertainty quantification studies on the thermal-hydraulic results and hydrogen production in the FPT1 experiment. Data comparison shows the current oxidation model of ISAA overestimates the hydrogen production rate during oxidation, but overall agrees well with experimental measurements. Local sensitivity analysis was also conducted for hydrogen production, further quantifying the impact of uncertainty parameters on numerical simulations. Sensitivity analysis shows the radial radiation heat transfer factor, power, and fuel rod failure criterion significantly impact numerical calculations during loss of coolant accident. A more mechanistic fuel rod failure model is crucial for numerical simulation of severe accident processes. The research not only contributes to refining and improving numerical models within analysis codes but also plays a significant role in reducing uncertainty associated with numerical simulations.
Effect of Neutron Leakage on Equilibrium U-Pu and Th-U Cycles for 16 Selected Reactors
Authors: Sabol Josef , Křepel Jiří
Published: November 2024

Three papers related to the equilibrium fuel cycle in 16 selected reactors were submitted to ICONE 31 conference. In this last part, the effect of neutron leakage from a finite core is evaluated.

This work deals with three main issues. The first goal is to verify when and how the modified one-group critical equation can be used to estimate the neutron leakage. Secondly, as the spectrum is changing together with the neutron leakage, it was another task to find how these changes would affect the equilibrium. And thirdly, because some of the reactors are supercritical in an infinite lattice, their minimal critical volume can be found and compared.

It was found that the critical equation cannot be used for fast reactors, especially for the U-Pu cycle, because due to the neutron leakage, the spectrum is harder and migration area with infinite multiplication factor are changing. Much better results were obtained with thermal reactors and for the Th-U cycle. When using new values obtained from a finite volume, the results match the reality more closely.

The same applies to the equilibrium calculation, where the largest differences were obtained for systems with large changes in the neutron spectrum. At the same time, it was found that the smaller the migration area, the smaller the volume is needed to show the change in the spectrum.

All results were obtained using the EQL0D v4 procedure and with ENDF/B-VIII.0 nuclear data library.
LES of Twin High-Re Rectangular Jets for Benchmarking Model Order Reduction Methods
Authors: Acierno John , Merzari Elia , Petrov Victor , Manera Annalisa
Published: November 2024

The study of turbulent mixing in non-isothermal coolant streams is crucial in understanding thermal striping, an oscillatory mixing pattern that can lead to thermal fatigue and degradation of internal components in advanced nuclear reactors. Thermal striping is linked closely to local 3D fine scales associated with turbulence. Historically, Large Eddy Simulation (LES) or Direct Numerical Simulation (DNS) were required to resolve these scales. Our investigation centers on the mixing dynamics within the Reactor Cavity Cooling System (RCCS) separate effects test facility. We study the interaction of two parallel-planar jets within a confined plenum to uncover flow mixing characteristics. Initially, LES simulations are employed to generate velocity and temperature statistics and time series data for comparison against future ROM approaches. Analysis of the velocity time series data using Power Spectrum Density (PSD) reveals a distinct low frequency mixing mode indicative of thermal striping. Subsequently, we utilize Proper Orthogonal Decomposition (POD) to extract dominant flow structures from 600 high-fidelity instantaneous velocity snapshots. These POD modes are utilized to construct a reduced-order model (ROM) capable of replicating the low frequency mode associated with thermal striping. By leveraging LES data with ROM techniques, we can efficiently and accurately predict the low frequency mode.
Experimental Studies on Two-Layer Stratified Molten Pool Heat Transfer With Water and 1-Octanol
Authors: Quan Fengyang , Pei Jie , Li Wei , Yuan Yidan
Published: November 2024

In the framework of severe accident studies, huge amount of tests have been carried out for molten pool’s heat transfer behavior in IVR configurations. However, there are still uncertainties in the range of high Rayleigh number (1016 to 1017). Besides, the impact of the metallic layer cannot be quantified. To analyze the influence of different simulants and the metallic layer, high temperature Stratified Molten POol Experiment facility (SAMPO), which designed by China Nuclear Power Engineering Co., LTD, is presented in this paper. The system plans to conduct melt pool tests on two-layer melt pools of different simulants working in low (below 100 °C), medium (around 300 °C), and high temperatures (above 500 °C) respectively. The effect of different heat release rates of different pool volumes on the internal Rayleigh number and heat transfer at the pool boundary under the same pool height conditions. The The low temperature test result with water and 1-octanol is presented in this study, meanwhile, the reliability of the experimental system has been verified through low-temperature testing.
Study on Thermal-Hydraulic Characteristics of Horizontal Lead-Based Reactor Whole Core
Authors: Gui Minyang , Wu Di , Zhang Hangyuan , Zhang Senmiao , Cheng Hui
Published: November 2024

Lead-based Fast Reactor (LFR) has high power density, strong inherent safety, and excellent maneuverability, which can meet the requirements of the multi-purpose nuclear power plant. In some specific scenarios, due to space constraints, the reactor core needs to be positioned horizontally, and the thermal-hydraulic characteristics will be different from those under vertical conditions.

According to the special structure and operational characteristics of horizontal LFR, the subchannel analysis code SACOS-HLFR was developed in this paper. With the subchannel code, the thermal-hydraulic evaluation of the whole core in horizontal LFR was conducted, mainly focusing on the flow and temperature distribution of the hottest assembly. In the whole core analysis, the outlet coolant temperature of the hottest assembly increases first and then decreases along the gravity direction. In contrast to the single assembly analysis, the flow and temperature difference between the upper and lower of the hottest assembly is significantly reduced due to the crossflow mixing with adjacent assemblies. At the same time, the position of the hottest channel is moved from the upper region of the assembly to the lower region. For the hottest rod, the maximum temperature of the cladding and pellet does not exceed the corresponding limit value, the reactor code can operate safely.
X-ray photoelectron spectroscopy analysis of electrospun polyacrylonitrile fibers: Pre- and post-thermal stabilization investigations
Authors: Amirali E. , Chronopoulos I. , Yannopoulos S. N. , Sygellou L.
Published: November 2024

Polyacrylonitrile (PAN) is a hard, rigid, thermoplastic substance with various applications, including carbon fiber production for the aerospace and automotive sectors, textile manufacturing, and water and air filtration. Its usage as a synthetic resin is particularly notable in its stabilized form. Stabilization ensures thermal stability during graphitization by transforming the structure from linear to lateral, resulting in an aromatic ladder. In this study, an 8% w/w polyacrylonitrile solution in N,N-dimethylformamide is electrospun and subsequently stabilized by heating up to 280 °C. The electrospun sample (pristine material) and its stabilized form at 280 °C in air were analyzed using x-ray photoelectron spectroscopy (XPS) at room temperature with a nonmonochromatic Mg Kα x-ray source.
Prediction of the sound transmission loss of shape-varied sonic crystals: A transfer matrix approach
Authors: Plé Jeremy , Kone Tenon Charly , Lehocine Allaeddine Benchikh , Panneton Raymond
Published: November 2024

This paper proposes a transfer matrix method (TMM) for modeling sonic crystals to predict the transmission loss of noise exiting an air extraction system. Because the crystals may be of different shapes (e.g., square, circular, or standardized airfoil profile to minimize airflow resistance) and must account for thermo-viscous losses, a discrete version of the TMM is used. Similar to the finite element method, a discretization of the geometry is first performed. Each element is modeled with a transfer matrix (TM) that includes the local thermo-viscous losses which attenuate the sound wave. For each element in parallel, the parallel TMM is employed. For the subsequently created elements in series, the classic TMM is used. This generates a global TM from which the sound transmission loss of the crystal network is deduced. The predictions obtained by the proposed method are compared to measurements in an acoustic tube for three different shapes of sonic crystals. The results show that a geometric tortuosity correction is necessary for the predicted bandgap center frequency to match the measurement. A correction is proposed, but this requires a possible refinement for more complicated profiles.
Sound source locations and their roles in Japanese voiceless “glottal” fricative production
Authors: Yoshinaga Tsukasa , Maekawa Kikuo , Iida Akiyoshi
Published: November 2024

Although [h] is described as a glottal fricative, it has never been demonstrated whether [h] has its source exclusively at the glottis. In this study, sound source locations and their influence on sound amplitudes were investigated by conducting mechanical experiments and airflow simulations. Vocal tract data of [h] were obtained in three phonemic contexts from two native Japanese subjects using three-dimensional static magnetic resonance imaging (MRI). Acrylic vocal tract replicas were constructed, and the sound was reproduced by supplying airflow to the vocal tracts with adducted or abducted vocal folds. The sound source locations were estimated by solving the Navier–Stokes equations. The results showed that the amplitudes of sounds produced by the vocal tracts with an open glottis were in a similar range (±3 dB) to those with a glottal gap of 3 mm in some contexts. The sound sources in these cases were observed in the pharyngeal cavity or near the soft palate. Similar degrees of oral constrictions were observed in the real-time MRI, indicating that the sound traditionally described as [h] is produced, at least in some contexts, with sound sources of turbulent flow generated by a supralaryngeal constriction of the following vowel.
Elevated incidence of infant botulism in a 17-county area of the Mid-Atlantic region in the United States, 2000–2019, including association with soil types
Authors: Dabritz Haydee A. , Friberg Ingrid K. , Payne Jessica R. , Moreno-Gorrin Camille , Lunquest Kristy , Thomas Deepam , Newman Alexandra P. , Negrón Elizabeth A. , Drohan Patrick J.
Published: October 2024

We sought to identify counties in the northeastern United States where the incidence of infant botulism (IB) is elevated compared to the nationwide incidence and to assess associations with soil type at the case residence. IB cases were identified through the distribution of the orphan drug Human Botulism Immune Globulin Intravenous for treatment of IB by state and national surveillance systems and were subsequently confirmed by laboratory testing. IB incidence by county was calculated as the number of IB cases divided by the number of live births in the county from 2000 to 2019. Cases were spatially mapped and assigned to soil types using the US Department of Agriculture’s online soils database. Possible association with soil type was evaluated with the Chi-squared test. We identified a rectangular area consisting of 17 contiguous counties in Delaware, Maryland, New Jersey, New York, and Pennsylvania, approximately 80 km by 250 km, in which the 20-year incidence of IB was nearly seven times greater than that of the remaining counties in those five states. Within this area, case residences were strongly associated with certain soil types (
P
≤ 0.003). From 2000 to 2019, IB occurred with disproportionate incidence in a rectangular area encompassing the lower Delaware and Raritan River Valley and parts of five adjacent states. Further investigation of the soils in counties from this area could assess whether
C. botulinum
is more prevalent in certain soil types and whether isolation of
C. botulinum
is more common in counties with higher IB incidence.

IMPORTANCE

Infant botulism occurs more frequently in 17 counties within and adjacent to the Delaware and Raritan River watersheds. This study should alert physicians and pediatricians in the area to the higher likelihood of encountering cases of this otherwise rare disease that manifests with constipation, poor feeding, loss of head control, weak suck/cry, generalized weakness, and descending bilateral paralysis.
A type VI secretion system in
Burkholderia
species
cenocepacia
and
orbicola
triggers distinct macrophage death pathways independent of the pyrin inflammasome
Authors: Loeven Nicole A. , Dabi Clarrisa , Pennington Joseph P. , Reuven Arianna D. , McGee Abigail P. , Mwaura Bethany W. , Bliska James B.
Published: October 2024

The
Burkholderia cepacia
complex contains opportunistic pathogens that cause chronic infections and inflammation in the lungs of people with cystic fibrosis. Two closely related species within this complex are
Burkholderia cenocepacia
and the recently classified
Burkholderia orbicola. B. cenocepacia
and
B. orbicola
encode a type VI secretion system and the effector TecA, which is detected by the pyrin/caspase-1 inflammasome, and triggers macrophage inflammatory death. We previously showed that the pyrin inflammasome was dispensable for lung inflammation in mice infected with
B. orbicola
AU1054
,
indicating this species activates an alternative pathway of macrophage inflammatory death. Notably,
B. cenocepacia
strains J2315 and K56-2 can damage macrophage phagosomes, and K56-2 triggers activation of the caspase-11 inflammasome, which detects cytosolic lipopolysaccharide. Here, we investigated inflammatory cell death in pyrin- (
Mefv
-/-
) or caspase-1/caspase-11- (

Casp1/11
-/-

) deficient mouse macrophages infected with
B. cenocepacia
J2315 or K56-2 or
B. orbicola
AU1054 or PC184. Macrophage inflammatory death was measured by cleavage of gasdermin D protein, the release of cytokines IL-1α and IL-1β, and plasma membrane rupture. We found that J2315 and K56-2 are detected by the caspase-11 inflammasome in
Mefv
-/-
macrophages, resulting in IL-1β release. By contrast, inflammasome activation was not detected in
Mefv
-/-
macrophages infected with AU1054 or PC184. Instead, AU1054 triggered an alternative macrophage inflammatory death pathway that required TecA and resulted in plasma membrane rupture and IL-1α release. Structural modeling of TecA orthologs in
B. cenocepacia
and
B. orbicola
suggested that amino acid changes in the latter may underlie its ability to trigger a non-inflammasome macrophage death pathway.
Performance of the LifeScale automated rapid phenotypic antimicrobial susceptibility testing on Gram-negative rods directly from positive blood cultures
Authors: Snyder James W. , Chaudhry Nadia , Hoffmann Wesley
Published: October 2024

Rapid antimicrobial susceptibility testing (rAST) performed directly from blood cultures is essential to influencing the selection of appropriate antibiotics, preferably targeted therapy, for the treatment of bloodstream infections. Affinity Biosensors has developed the LifeScale, a phenotypic rAST system based on microfluidic sensors with a mechanical resonator that measures the mass of individual microbes. The combination of replication, biomass, and population profiling of individual microbes is analyzed to produce rAST results. The performance of the LifeScale was evaluated and compared to our current standard of care (SOC) antimicrobial susceptibility testing (AST) system under clinical conditions. The results indicated that the LifeScale is easy to use and provides rapid, reliable, and accurate AST results in less than 5 h directly from from positive blood cultures containing Gram-negative organisms listed in the current database. For all organism–antibiotic combinations involving polymicrobial cultures, LifeScale showed a resistant result when either mixed isolate was resistant. If these results prove to be robust on further testing, this may justify the reporting of rapid LifeScale results without the need for additional confirmatory testing.

IMPORTANCE

This is the first clinical-based study of a unique technology using microfluidic sensors to generate rapid antimicrobial susceptibility test results directly from blood cultures containing Gram-negative rods. The issue of polymicrobial cultures was also addressed in this study, which, to our knowledge, has not been addressed in publications of other rapid phenotypic AST systems. Overall, LifeScale results compared favorably with the SOC in terms of overall agreement, especially categorical agreement.
Fine-tuned spatiotemporal dynamics of DNA replication during phage lambda infection
Authors: Yu Zihao , Guan Jingwen , Hanson Catherine , Duong Trish , Zeng Lanying
Published: October 2024

After the ejection of viral DNA into the host cytoplasm, the temperate bacteriophage (phage) lambda integrates a cascade of expressions from various regulatory genes, coupled with DNA replication, to commit to a decision between lysis and lysogeny. Higher multiplicity of infection (MOI) greatly shifts the decision toward the lysogenic pathway. However, how the phage separates the MOI from replicated viral DNA during lysis–lysogeny decision-making is unclear. To quantitatively understand the role of viral DNA replication, we constructed a reporter system facilitating the visualization of individual copies of phage DNA throughout the phage life cycle, along with the lysis–lysogeny reporters. We showed that intracellular viral DNA diverges between the lytic and lysogenic pathways from the early phase of the infection cycle, mostly due to the synchronization and success of DNA injection, as well as the competition for replication resources, rather than the replication rate. Strikingly, we observed two distinct replication patterns during lysogenization and surprisingly heterogeneous integration kinetics, which advances our understanding of temperate phage life cycles. We revealed that the weak repression function of Cro is critical for an optimal replication rate and plays a crucial role in establishing stable lysogens.

IMPORTANCE

Temperate bacteriophages, such as lambda, incorporate environmental cues including host abundance and nutrient conditions to make optimal decisions between propagation and dormancy. A higher phage-to-host ratio or multiplicity of infection (MOI) during λ infection strongly biases toward lysogeny. However, a comprehensive understanding of this decision-making process and the impact of phage replication prior to the decision is yet to be achieved. Here, we used fluorescence microscopy to quantitatively track the spatiotemporal progression of viral DNA replication in individual cells with different cell fates. The implementation of this fluorescent reporter system and quantitative analysis workflow opens a new avenue for future studies to delve deeper into various types of virus–host interactions at a high resolution.
PF-00835231 broadly inhibits swine Alpha-coronavirus, including emerging SADS-CoV
Authors: Shi Lei , Duan Yueyue , Cao Liyan , Zhang Yu , Yuan Cong , Sun Maowen , Zhang Juan , Kong Xiangyu , Zheng Haixue , Wang Qi
Published: October 2024

Swine Alpha-coronaviruses are one of the most destructive pathogens affecting the swine industries across the world. Swine Alpha-coronaviruses include transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus, porcine respiratory coronavirus, and swine acute diarrhea syndrome coronavirus (SADS-CoV). Thus far, swine Alpha-coronaviruses treatment options are very limited. Therefore, the identification of safe and effective treatment of swine Alpha-coronaviruses is urgently needed. In the current study, we screened a library of 240 FDA-approved compounds for antiviral activity against TGEV. Among screening, the 3CL protease inhibitor PF-00835231 was shown to dramatically inhibit TGEV replication
in vitro
systems. Mechanistically, PF-00835231 inhibits nonstructural protein 5 (Nsp5) protease activity targeting the cleavage at Nsp5–Nsp6 of TGEV. Additionally, PF-00835231 exhibited the potent broad-spectrum swine Alpha-coronaviruses antiviral activity. Treatment of PF-00835231 in mice not only blocks SADS-CoV deadly infection but also dramatically reduces viral copies. Taken together, our study provides evidence that PF-00835231 may control of the current swine Alpha-coronaviruses and emerging swine Alpha-coronaviruses in the future.

IMPORTANCE

The COVID-19 pandemic has induced tremendous efforts to develop therapeutic strategies that target Beta-coronavirus including SARS-CoV-2. 3CL protease of Beta-coronavirus has been as a drug target for developing antiviral drugs. However, 3CL protease is not conserved in Alpha-coronavirus and Beta-coronavirus with only 44% amino acid similarity. Therefore, an inhibitor that prevents Alpha-coronaviruses infection is urgently needed. Swine Alpha-coronaviruses are one of the most destructive pathogens affecting the swine industries across the world. Swine herds with coronavirus diarrhea showed a high rate of co-infection between different Alpha-coronavirus. Our study, for the first time, showed that PF-00835231 inhibits swine Alpha-coronavirus infection. At the mechanistic level, we experimentally identified that PF-00835231 inhibits nonstructural protein 5 (Nsp5) protease activity targeting the cleavage at Nsp5–Nsp6 of Alpha-coronaviruses.
From flow to furnace: Low viscosity of three-phase lavas measured at Kīlauea 2018 eruption conditions
Authors: Halverson Brenna A. , Whittington Alan
Published: November 2024

Melt composition, temperature, and crystallinity are often seen as the three most important characteristics driving lava rheology, which controls eruptive behavior. Traditional methods of measuring the viscosity of crystallizing basalts often yield different mineral characteristics to natural samples and are typically bubble-free. To quantify the viscosity of basalts inclusive of bubble and crystal cargo, we developed a new technique to measure high-temperature three-phase isothermal lava viscosity and applied it to samples from the 2018 eruption of Kīlauea. This new experimental technique begins at subliquidus temperatures, preserving original phenocrysts. A short experimental duration allows for the retention of most of the original bubble population (19%–31% vs. 36% in the original lava) and accurate replication of crystal textures from field samples, as documented in quenched postexperiment samples. The observed rheological behavior in these experiments, conducted at syneruptive temperatures (1150–1105 °C) and strain rates (0.4–18 s–1), should therefore be representative of the lava flows. We measured average viscosities of 116 Pa·s at 1150 °C to 167 Pa·s at 1115 °C (i.e., only 10%–25% higher than calculated liquid viscosities at those temperatures) and a maximum of 1800 Pa·s at 1105 °C. These results are much lower than viscosity measured in traditional bubble-free experiments, which plateaued at ~14,000 Pa·s at 1115 °C. Our results suggest the effect of bubbles in three-phase magmas may be greater than predicted by models based on two-phase bubbly liquids, and this effect must be included in realistic lava flow rheology models. The method proposed here supplies a framework for providing the necessary experimental constraints.
In vivo lacrimal gland imaging artefact assessment based on swept-source optical coherence tomography for dry eye disease
Authors: Cheng Weijing , Li Longyue , Chen Juejing , Chen Ziyan , Li Jing , Liu Siyi , Zhang Nuan , Gu Feng , Wang Wenhui , Wang Wei , Yang Boyu , Liang Lingyi
Published: November 2024

Background

This study aimed to characterise imaging artefacts in the lacrimal gland using swept-source optical coherence tomography (SS-OCT) in patients with dry eye disease (DED) and healthy participants and identify risk factors for these artefacts.

Methods

In total, 151 eyes, including 104 from patients with DED and 47 from non-DED participants, were analysed. Demographic data collection, comprehensive ocular examinations and SS-OCT imaging of the palpebral lobe of the lacrimal gland were performed. Artefacts were classified into distinct categories with different severities. Univariate and multivariate logistic regression analyses were performed to evaluate the association of age, gender, best-corrected visual acuity, intraocular pressure (IOP) and the presence of DED with the presence of artefacts.

Results

Eight artefact types and severity grading were defined by analysing 1208 lacrimal SS-OCT images. The three most prevalent artefacts were defocus (75.83%), cliff (67.47%) and Z-off (58.44%). The presence of artefacts was significantly associated with the presence of DED (OR=9.13; 95% CI, 2.39 to 34.88; p=0.001) and higher IOP (OR=1.34; 95% CI, 1.14 to 1.58; p<0.001). Furthermore, multivariate logistic analyses showed that lower tear film breakup time (OR=0.71; 95% CI, 0.55 to 0.92; p=0.009) and higher meibum quality score (OR=2.86; 95% CI, 1.49 to 5.48; p=0.002) were significantly associated with higher odds for the presence of artefacts.

Conclusions

DED eyes had more SS-OCT image artefacts than normal eyes. Stringent standardised image quality control should be implemented before further image analysis when using SS-OCT to assess lacrimal gland image.