bluuebunny/crossref_metadata_2025 huggingface dataset:
Algorithm design of a Rubik metamaterial for sextuple orbital angular momentums
Authors: Yang Xiaokun , Li Jingjing , Zhang Xueheng , Yang Chao
Published: April 2023

This letter presents a Rubik metamaterial with sextuple orbital angular momentum (OAM) capabilities. The design is based on a comprehensive algorithm that draws inspiration from the Rubik's cube. This metamaterial can generate multiple phased vortex waves using only one model and is easily constructed from metallic blocks with varying heights. The performance of the metamaterial is verified at 18 GHz with a gain of over 30 dB. A faster verification process is achieved using an automated program based on macroscript for height‐adjusted Rubik metamaterials, which is more efficient than manual operations. By calculating the purity of the sextuple OAMs, it can be determined that the Rubik model is capable of generating multiple phased vortex wave beams as effectively as possible. This Rubik metamaterial has potential applications in experimental and educational settings, particularly with the growing trend in three‐dimensional printing.
Occupational needle stick injuries and related factors among healthcare workers in military hospitals in Tehran
Authors: Sepandi Mojtaba , Alimohamadi Yousef , Afrashteh Sima , Rashti Roya
Published: April 2023

Aim

Healthcare workers (HCWs) are always at risk of experiencing occupational needle stick injuries (NSIs). The primary aim of this study was to assess the prevalence of NSIs among Iranian HCWs in military hospitals in Tehran.

Design

This cross‐sectional study was conducted in four military hospitals in the summer of 2019 in Tehran.

Method

By Census, 802 HCWs were included. Data were collected through a questionnaire consisting of vaccination history, safety equipment, use of safety box, history of NSIs and demographic variables. The logistics regression was used to estimate the odds ratios (OR) and 95% confidence interval (CI). The statistical significance level was set at 5%. The data were analysed using the SPSS software version 23.

Results

A total of 203 (25.3%, CI: 22.3–28.4) of the participants reported a history of NSIs at least once during the past year. Single HCWs had a higher risk of NSIs compared to married HCWs (OR: 1.59, 95% CI (1.09, 2.30)). Also, the night shift working (OR: 1.91, 95% CI (1.18, 3.12)), higher educational degree (OR: 2.25, 95% CI (1.21, 4.20)), working overtime (OR: 1.50, 95% CI: (1.07, 2.12)), older age (OR: 1.02, 95% CI (1.01, 1.04)) and needle recapping (OR: 2.90, 95% CI: (1.98, 4.22)) were identified as significant associated factors. The study draws attention to a relatively high prevalence of NSIs as well as high‐risk activities among military HCWs. The primary source of NSIs is needle recapping. Measures such as setting up training courses for the military HCWs are needed to be planned.
Student performance on mathematics CBMs across paper and tablet modalities
Authors: Reynolds Jennifer L. , Aspiranti Kathleen B. , Henze Erin E. C.
Published: April 2023

Tablet‐based technology has become a conduit for the administration of curriculum‐based measurement (CBM) tools. Using tablets to administer CBM probes has many advantages; however, little is known about how students perform on CBMs when administered via a tablet. The current investigation compared digits correct per minute obtained from 44 third‐grade students on CBM addition fluency probes administered via three different modalities. Students completed the probes using traditional paper and pencil, a tablet using their fingers to write the answer, or a tablet application using a keyboard to type the answer. A within‐subjects group design showed students performed significantly better on the tablet when using their finger to write the answer, even though most students (58%) indicated this was their least preferred modality. The discussion focuses on the implications for educators and the use of different CBM modalities for interindividual and intraindividual comparisons.
Effect of physical therapy timing on patient‐reported outcomes for individuals with acute low back pain: A systematic review with meta analysis of randomized controlled trials
Authors: McDevitt Amy W. , Cooper Catherine G. , Friedrich Jason M. , Anderson Dustin J. M. , Arnold Elizabeth A. , Clewley Derek J.
Published: April 2023

Objective

The purpose of this systematic review with meta‐analysis was to investigate the effect of early physical therapy (PT) for the management of acute low back pain (LBP) on patient‐reported outcomes of pain and disability, compared to delayed PT or non‐PT care.

Literature Survey

Randomized controlled trials in three electronic databases (MEDLINE, CINAHL, Embase) were searched from inception to June 12, 2020, and updated on September 23, 2021.

Methodology

Eligible participants were individuals with acute low back pain. The intervention was early PT compared to delayed PT or non‐PT care. Primary outcomes included the patient‐reported outcomes of pain and disability. The following information was extracted from included articles: demographic data, sample size, selection criteria, PT interventions, and pain and disability outcomes. Data were extracted following Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines. Methodological quality was assessed using the Physiotherapy Evidence Database (PEDro) Scale. Random effects models were used for the meta‐analysis.

Synthesis

Seven of 391 articles met the eligibility criteria and were included in the meta‐analysis. Random effects meta‐analysis comparing early PT to non‐PT care for acute LBP indicated a significant reduction in pain (standard mean difference [SMD] = 0.43, 95% confidence interval [CI]: −0.69 to −0.17) and disability (SMD = 0.36, 95% CI: −0.57 to −0.16) in the short term. Early PT compared to delayed PT did not result in improvement in short‐term pain (SMD = −0.24, 95% CI: −0.52 to 0.04) or disability (SMD = 0.28, 95% CI: −0.56 to 0.01), or long‐term pain (SMD = 0.21, 95% CI: −0.15 to 0.57) or disability (SMD = 0.14, 95% CI: −0.15 to 0.42).

Conclusions

This systematic review and meta‐analysis suggest early PT versus non‐PT care is associated with statistically significant reductions in short‐term pain and disability (up to 6 weeks) with small effect sizes. The results indicate a nonsignificant trend favoring a small benefit of early PT over delayed PT for outcomes at short‐term follow‐up but no effect at long‐term follow‐up (6 months or greater).
Interspecific and intraspecific variation in susceptibility of two co‐occurring pest thrips, Frankliniella occidentalis and Thrips palmi, to nine insecticides
Authors: Shen Xiu‐Jing , Chen Jin‐Cui , Cao Li‐Jun , Ma Zhong‐Zheng , Sun Li‐Na , Gao Yong‐Fu , Ma Li‐Jun , Wang Jia‐Xu , Ren Ya‐Jing , Cao Hua‐Qian , Gong Ya‐Jun , Hoffmann Anthony Ary , Wei Shu‐Jun
Published: April 2023

BACKGROUND

Field control of pest thrips mainly relies on insecticides, but the toxicity of insecticides can vary among thrips species and populations. In this study, we examined the susceptibility of multiple field populations of two thrips pests, Frankliniella occidentalis, and Thrips palmi, that often co‐occur on vegetables, to nine insecticides belonging to seven subgroups.

RESULTS

The highest level of variation in susceptibility among F. occidentalis populations was for spinetoram (73.92 fold difference between most resistant and most susceptible population), followed by three neonicotinoids (8.06–15.99 fold), while among T. palmi populations, it was also for spinetoram (257.19 fold), followed by emamectin benzoate, sulfoxaflor, and acetamiprid (23.64–45.50 fold). These findings suggest evolved resistance to these insecticides in some populations of the two thrips. One population of F. occidentalis had a particularly high level of resistance overall, being the most resistant for five of the nine insecticides tested. Likewise, a population of T. palmi had high resistance to all nine insecticides, again suggesting the evolution of resistance to multiple chemicals. For F. occidentalis, the LC95 values of most populations were higher than the field‐recommended dosage for all insecticides except chlorfenapyr and emamectin benzoate. For several T. palmi populations, the LC95 values also tended to be higher than recommended dosages, except in the case of emamectin benzoate and spinetoram.

CONCLUSIONS

Our study found interspecific and intraspecific variations in the susceptibility of two thrips to nine insecticides and multiple resistance in some populations, highlighting the need for ongoing monitoring and resistance management. © 2023 Society of Chemical Industry.
Spin‐Polarized Edge‐State Transport in L‐Shaped MoS2 Nanodevice Modulated by Exchange Field and Electric Field
Authors: Feng Bing-Yang , Ye En-Jia , Sun Yun-Lei
Published: April 2023

Herein, the spin‐polarized edge‐state transport properties in L‐shaped zigzag nanodevice () are investigated based on tight‐binding model, Green's function method, and ballistic transport theory. The spin conductance and spin polarization are calculated by considering external exchange field and electric field. It is shown in the results that the spin conductance is closely related to the configuration of atomic non‐consistence on the edge of . Meanwhile, the spin conductance is determined by the spin channel opening on the edge, which can be modulated by external fields. The configuration characteristic and external fields give rise to effects of sublattice mismatch and spin mismatch on the edge channels, respectively. As a consequence, mismatch effects are actually employed to modulate the spin channel on the edge of , and 100% spin polarization is realized selectively. Moreover, the corresponding local density of states distributions are plotted to reveal the modulation of the spin‐resolved edge‐state and the spin‐filtering effects in the real space. These spin‐polarized edge‐state transport properties in can have potential application in various kinds of spin valves and spin filters in nanocircuits.
Thermal Characterization of Micrometric Polymeric Thin Films by Photoacoustic Spectroscopy
Authors: Fernández-Olaya Mareny Guadalupe , Franco-Bacca Adriana Paola , Martínez-Torres Pablo Genaro , Ruiz-Gómez Miguel Angel , Meneses-Rodríguez David , Li Voti Roberto , Alvarado-Gil Juan José
Published: April 2023

In materials science, the knowledge of the thermal properties of thin films on thick substrates is crucial in determining the role of the film in the physical properties of the entire system. Even though the role of the film can be very important, the determination of its thermal properties is a challenging task due to the fact that its contribution to heat transfer is generally hard to single out from the influence of the substrate. Herein, a simple analytical methodology, based on the photoacoustic technique, useful in the thermal characterization of thin films on thick substrates, is presented. The approach is based on illuminating one side of the substrate with a modulated laser beam and monitoring the thermal contrast when a thin film is formed on the opposite side. This methodology allows to unambiguously determine the volumetric heat capacity of micrometric polymeric thin films. The limits of applicability of the method as well as the possibility of performing a full characterization of the thermal properties of the film are discussed.
A rare case of hemophagocytic lymphohistiocytosis mimicking flare of systemic lupus erythematosus
Authors: Tiwana Areeb , Tiwana Maida , Wang Jiang , Khawar Muhammad Umair
Published: April 2023

The Ohio and Mississippi River Valleys are endemic to histoplasmosis. It is usually self‐limiting in immunocompetent people, but it can cause morbidity and mortality if not detected early in people with an underlying autoimmune disease. Disseminated Histoplasmosis induced hemophagocytic lymphohistiocytosis (HLH) mimicking the flare of an underlying autoimmune disease, is uncommon in the published literature. Disseminated histoplasmosis (DH) can cause multiorgan involvement, especially in a patient with an underlying autoimmune disease. We present the case of a 24‐year‐old female with HLH who was initially treated as a flare of autoimmune disease but later etiology was confirmed as disseminated histoplasmosis on bone marrow histopathological examination.
Quality by Design approach for a planar chromatographic method for simultaneous estimation of Ivabradine Hydrochloride and Carvedilol in pharmaceutical formulation
Authors: Chadha Hiteshi , Parmar Rajesh , Shah Purvi , Patel Kalpana
Published: April 2023

Box‐Behnken design was applied for the development of a novel, precise, simple, and accurate high‐performance thin‐layer chromatography method for simultaneous estimation of mentioned drugs in the formulation. Optimization was performed using Quality by Design. Principles of risk assessment followed by application of design for optimization of chromatographic conditions to determine critical parameters: volume of hexane, chamber saturation time, solvent front and their effects on critical method attributes: Rf values of both drugs. Optimized conditions were determined through Derringer's desirability approach of the multi‐criteria decision‐making technique. Good resolution using optimized mobile phase, hexane:ethyl acetate:ammonium acetate in methanol (5.1:3:2) with Rf values 0.34 and 0.67 for Ivabradine Hydrochloride and Carvedilol, respectively, was obtained. The method was validated as per International Council on Harmonization having a linear range of 1000–5000 ng/band of Ivabradine and 1250–6250 ng/band for Carvedilol, respectively. %Recovery was in range of 99.23–101.3 and 99.8–100.5, respectively. Precision and robustness were found to be in an acceptable range. Thus, Quality by Design based method development assisted in making design space with knowledge of all method performance characteristics with a better understanding of high‐performance thin‐layer chromatography. The Analytical GREEnness profile was assessed using AGREE tool with an overall reliable score of 0.68.
Size effect on dynamic compressive failure mode and mechanical properties of recycled concrete
Authors: Liu Chunyang , Gao Yingqi , Luan Kaiye , Su Jing , Lin Yuying
Published: April 2023

In order to study the size effect behavior of recycled concrete under dynamic compression load, a meso‐scale model of recycled concrete was established. The particle size of coarse aggregate, replacement ratio of recycled coarse aggregate, and section size were used as parameters to explore the mechanical properties of recycled concrete under uniaxial dynamic compression load, such as failure mode, compressive strength, peak strain, and residual strength. The effects of strain rate, particle size of recycled coarse aggregate, and replacement rate of recycled coarse aggregate on the size effect of dynamic compression of recycled concrete were further analyzed. The results showed that under uniaxial dynamic compression load, the damage degree of recycled concrete deep and along with the change of the strain rate change, recycled concrete dynamic compression strength and strain rate were positively correlated. There is the critical strain rate is 1/s, which weaken the influence of the size effect, when the strain rate reaches 10/s, the dynamic compressive strength of recycled concrete increases with the increase of section size. At the same time, when the strain rate is high, the particle size of recycled coarse aggregate and the replacement rate of recycled coarse aggregate have little effect on the size effect behavior of recycled concrete.
Organocatalytic Synthesis of Chiral Halogenated Compounds
Authors: Shibatomi Kazutaka
Published: April 2023

This account summarizes our recent efforts in the enantioselective organocatalytic synthesis of chiral halogenated compounds. The enantioselective α‐halogenation of aldehydes, decarboxylative chlorination of β‐keto acids, and enantioselective C−C bond formation at the trifluoromethylated prochiral carbon to yield the corresponding organohalides with chlorinated, fluorinated, or trifluoromethylated chiral stereogenic centers are discussed. We applied common organocatalysts, such as Jørgensen‐Hayashi catalyst and cinchona alkaloid‐derivatived catalyst, and developed novel chiral amine catalysts for these reactions. This account also discusses stereospecific derivatizations of the resulting chiral halogenated compounds via nucleophilic substitution. Thus, we synthesized many novel chiral compounds that have not been reported, even as racemates.
The effectiveness of goreisan, for gestational edema and amniotic fluid decrease
Authors: Makimoto Fukashi
Published: April 2023

Objective

Ordinarily, a diuretic uniformly performs diuresis of body water and decreases it. When a diuretic is used for gestational edema, blood vessel dehydration and amniotic fluid are expected to decrease. This may be rather harmful for the gestational prognosis. Goreisan's mechanism of efficacy is different from that of ordinary diuretics. The results of treating gestational edema and amniotic fluid reduction with goreisan were studied. Whether goreisan is helpful for improving gestational prognosis was studied.

Clinical results

Goreisan is effective in the treatment of gestational edema. During edematous treatment, goreisan exhibits a diuretic effect. After edema has improved, goreisan does not exhibit a compulsory diuresis effect. These effects were ascertained by examining the change in the expectant mother's weight. Goreisan appeared to normalize the gross body water volume. In the presence of edema, a reduction in the amniotic fluid volume was often apparent after 36 weeks of gestation. Treatment of gestational edema by goreisan prevented the reduction of the amniotic fluid volume. Maximum vertical pocket (MVP) changes before and after treatment with goreisan for oligohydramnios were studied. Goreisan prospectively appeared to exhibit a therapeutic effect on oligohydramnios.

Conclusion

Goreisan contributes to improvement in the prognosis of the course of gestation. Goreisan, rather than diuretics, corrects the maldistribution of body water. Only Kampo medicine has these activities for water metabolism. Ordinary diuretics cannot be substituted for these medicines.
Microneedle‐assisted transdermal delivery of nanoparticles: Recent insights and prospects
Authors: Guillot Antonio José , Martínez‐Navarrete Miquel , Zinchuk‐Mironova Valeria , Melero Ana
Published: April 2023

Transdermal delivery of drugs offers an interesting alternative for the administration of molecules that present certain troubles when delivered by the oral route. It can produce systemic effects or perform a local action when the formulation exerts an optimal controlled drug release or a targeted delivery to the specific cell type or site. It also avoids several inconveniences of the oral administration such as the hepatic first pass effect, gastric pH‐induced hydrolysis, drug malabsorption because of certain diseases or surgeries, and unpleasant organoleptic properties. Nanomedicine and microneedle array patches (MAPs) are two of the trendiest delivery systems applied to transdermal research nowadays. However, the skin is a protective barrier and nanoparticles (NPs) cannot pass through the intact stratum corneum. The association of NPs and MAPs (NPs@MAPs) work synergistically, since MAPs assist NPs to bypass the outer skin layers, and NPs contribute to the system providing controlled drug release and targeted delivery. Vaccination and tailored therapies have been proposed as fields where both NPs and MAPs have great potential due to inherent characteristics. MAPs conception and easy use could allow self‐administration and therefore facilitate mass vaccination campaigns in undeveloped areas with weak healthcare services. Additionally, nanomedicine is being explored as a platform to personalize therapies in such an important field as oncology. In this work we show recent insights that prove the benefits of NPs@MAPs association and analyze the prospects and the discrete interest of the industry in NPs@MAPs, evaluating different limiting steps that restricts NPs@MAPs translation to the clinical practice.

This article is categorized under:

Nanotechnology Approaches to Biology > NA

Therapeutic Approaches and Drug Discovery > NA
Utilizing functional cell‐free extracts to dissect ribonucleoprotein complex biology at single‐molecule resolution
Authors: Duran Elizabeth , Schmidt Andreas , Welty Robb , Jalihal Ameya P. , Pitchiaya Sethuramasundaram , Walter Nils G.
Published: April 2023

Cellular machineries that drive and regulate gene expression often rely on the coordinated assembly and interaction of a multitude of proteins and RNA together called ribonucleoprotein complexes (RNPs). As such, it is challenging to fully reconstitute these cellular machines recombinantly and gain mechanistic understanding of how they operate and are regulated within the complex environment that is the cell. One strategy for overcoming this challenge is to perform single molecule fluorescence microscopy studies within crude or recombinantly supplemented cell extracts. This strategy enables elucidation of the interaction and kinetic behavior of specific fluorescently labeled biomolecules within RNPs under conditions that approximate native cellular environments. In this review, we describe single molecule fluorescence microcopy approaches that dissect RNP‐driven processes within cellular extracts, highlighting general strategies used in these methods. We further survey biological advances in the areas of pre‐mRNA splicing and transcription regulation that have been facilitated through this approach. Finally, we conclude with a summary of practical considerations for the implementation of the featured approaches to facilitate their broader future implementation in dissecting the mechanisms of RNP‐driven cellular processes.

This article is categorized under:

RNA Structure and Dynamics > RNA Structure, Dynamics and Chemistry

RNA Interactions with Proteins and Other Molecules > RNA‐Protein Complexes

RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems
Physiological and engineered tRNA aminoacylation
Authors: Tijaro‐Bulla Santiago , Nyandwi Samuel Protais , Cui Haissi
Published: April 2023

Aminoacyl‐tRNA synthetases form the protein family that controls the interpretation of the genetic code, with tRNA aminoacylation being the key chemical step during which an amino acid is assigned to a corresponding sequence of nucleic acids. In consequence, aminoacyl‐tRNA synthetases have been studied in their physiological context, in disease states, and as tools for synthetic biology to enable the expansion of the genetic code. Here, we review the fundamentals of aminoacyl‐tRNA synthetase biology and classification, with a focus on mammalian cytoplasmic enzymes. We compile evidence that the localization of aminoacyl‐tRNA synthetases can be critical in health and disease. In addition, we discuss evidence from synthetic biology which made use of the importance of subcellular localization for efficient manipulation of the protein synthesis machinery.

This article is categorized under:

RNA Processing

Translation > Translation Regulation

RNA Processing > tRNA Processing

RNA Export and Localization > RNA Localization
Application of BIM Technology in Nuclear Power Construction Schedule Management
Authors: Yan Jiafu , Xie Yonghui , Zhou Zhigang
Published: April 2023

Schedule management is one of the important contents of nuclear power project management, which often leads to the lack of theoretical system due to the lack of sufficient information support. BIM technology provides a new solution for nuclear power project schedule management, ensures the effective linkage of all levels of schedule, reduces project delay and saves construction time. Combined with the theoretical basis of BIM and the characteristics of nuclear power project schedule management, this paper summarizes the application advantages of BIM technology in nuclear power construction schedule management.
Visualized Numerical Analysis of Fustar Reactor Based on Modelica Language
Authors: He Xuan’ang , Zhang Dalin , Wang Xiang
Published: April 2023

FuSTAR is a new small fluoride-salt-cooled high-temperature reactor designed for the energy needs of remote western regions. The TRISO fuel and helical cruciform fuel elements used in FuSTAR and the integrated core design enables inherent safety. Modelica is a process description language based on object equations. It has key features such as non-causal expression and model reuse, which achieve repeatable visual modeling by connecting components. By modeling and simulating FuSTAR using the Modelica, studies were carried out under steady-state as well as multiple transients to understand the primary loop system response of FuSTAR under accident scenarios. The results show that the parameters of the primary loop system cannot exceed the safety limit with the insertion of step reactivity and after changing the size of the temperature coefficient of reactivity, the model can give a reasonable response.
Heat Pipe Temperature Oscillation Effects on Solid-State Reactor Operation
Authors: Ma Yugao , Zhao Yicheng , Yu Hongxing , Huang Shanfang , Deng Jian , Chai Xiaoming
Published: April 2023

The alkali metal heat pipes are the critical heat transfer elements in heat pipe cooled reactors. However, there are instabilities in heat pipes such as geyser boiling, resulting in temperature oscillation and even threatening the reactor safety. This work developed a coupled neutronic and thermal-mechanical analysis method to analyze the effects of geyser boiling and heat pipe temperature oscillations on the critical parameters, e.g., temperature and stress, during reactor operation.
The megawatt heat pipe reactor MegaPower was chosen as an application case. The simulations show that the heat pipe temperature oscillation leads to the same frequency oscillation of the temperature and stress in the solid-state core. Besides, the temperature amplitudes are significantly reduced by shortening the oscillation period. Reducing the oscillation period from 60 s to 15 s reduced the temperature amplitude of the fuel pellet center from 22℃ to 5℃. Furthermore, the stress oscillation in the core may lead to material fatigue or even failure for a long period of operation, which is highly undesired. This work can provide valuable data and references for the safety design of heat pipe reactors.
Uncertainty Analysis and Sensitivity Evaluation of a Main Steam Line Break Accident on an Advanced PWR
Authors: Zhang Xueyan , Zhang Yixuan , Yang Ye , Deng Chengcheng , Yang Jun
Published: April 2023

A RELAP5 input model was established for a scaled-up facility simulating China's Advanced Passive Water Reactor with passive safety features. The simulation was performed to reproduce a Main Steam Line Break (MSLB) scenario at steam line connected to one Steam Generator. The figure of merit selected in this accident scenario includes the maximum containment pressure, mass and energy release to containment. Driving factors of this response function include Passive Residue Heat Removal material thermal conductivity, Pressurizer temperature, and broken steam line temperature.

To achieve an adequately justified safety margin using a Best Estimate Plus Uncertainty analysis, dominant phenomena were selected from a reference Phenomenon Identification and Ranking Table. The calculation results were compared with the available reference data of similar Generation III Passive Water Reactor to assess the code's capability to predict the MSLB phenomena. The DAKOTA toolkit is used to drive both parameter sensitivity analysis and uncertainty propagation. The 95/95 uncertainty bands of key output parameters were obtained using the Wilks’ statistical methods.

Compared with the reference data, the simulation results partially confirmed the stability and repeatability of the code model for initial and boundary condition perturbations. The uncertainty bands of important output parameters were demonstrated. The results indicated that the maximum containment pressure value was below the safety limit, and the passive safety system can mitigate the consequence of the MSLB. The mass and energy released into the containment were assessed according to the containment design.

The parameter sensitivity analysis was performed with 34 input parameters, and the results were evaluated by Spearman's Simple Rank Correlation Coefficients.
Research on Re-extraction Technology for Uranium Refining Based on Fractionation Extraction
Authors: Zhou Zhiquan , Ren Yan , Ye Kaikai , Niu Yuqing , Zhang Jiayu , Meng Shu , Kang Shaohui , Cao Xiaohao , Li Dabing
Published: April 2023

TBP extraction in nitric acid system is the core purification process of the wet method for uranium refining and conversion. Reextraction for uranium refining based on fractionation extraction was proposed, according to the characteristics and requirements of uranium refining extraction. The operation line and step line of reextraction were obtained through mathematical model, and the control law is explained. The reextraction bench test was carried out to investigate the stable operation and the concentration variation of the related components. The study shows that the reextraction process can run stably. After extraction, the concentration of uranium in organic phase can reach 120g/L, the extraction saturation can reach 96.7%, the concentration of uranium in raffinate is less than 10mg/L, and the concentration of impurity components is greatly reduced. Reextraction technology can facility the control of uranium refining extraction, which maintains the state of high saturation vs. low raffinate concentration.
Development and Preliminary Verification of a Neutronics-Thermal Hydraulics Coupling Code for Research Reactors with Unstructured Meshes
Authors: Yang Mingrui , Luo Chixu , Wang Dan , Wang Tianxiong , Liu Xiaojing , Zhang Tengfei
Published: April 2023

To maximize their adaptability and versatility, research reactors are designed to adapt to various operational conditions. These requirements result in more complex configurations and irregular geometries for research reactors. Besides, there is usually a strong coupling of neutronics-thermal hydraulics (N-TH) fields inside the reactor. A three-dimensional N-TH coupling code has been developed named CENTUM (CodE for N-Th coupling with Unstructured Mesh). Steady-state and transient neutronic analyses are performed using a 3D triangular-z nodal transport solver with the stiffness confinement method (SCM). Meanwhile, thermal-hydraulics calculations adopt a multi-channel model. For a preliminary verification of the code, we examine CENTUM with benchmark problems including TWIGL, 3D-LMW, and NEACRP. CENTUM produces maximum power errors of −1.27% and −0.45% for the TWIGL A1 and A2 cases, respectively. For the 3D-LMW benchmark, the largest relative power error of 3.84% is observed at 10 s compared with the reference SPANDEX code. For the NEACRP N-TH coupling benchmark, CENTUM results in a 0.35 ppm error in critical boron concentration, a 2.16 °C discrepancy in the fuel average Doppler temperature, and a 0.63% overestimation in the maximum axial power. Moreover, transient results considering thermal-hydraulics feedback are in good agreement with the PARCS reference solutions, with the maximum relative power deviation being only 0.055%.
Structure Design and Optimization of the Mass Flow Distribution Device of Downcomer for Fluoride-Salt-Cooled High-Temperature Advanced Reactor – FuSTAR
Authors: Li Xinyu , Zhang Dalin , Zhou Xingguang , Tian Wenxi , Qiu Suizheng
Published: April 2023

The new generation of water-free cooling reactors: the FuSTAR system (Fluoride-Salt-cooled high-Temperature Advanced Reactor), mainly proposed by Xi’an Jiaotong University, is at the design stage. So far, the overall parameters of the heat transport system of FuSTAR have been obtained, and there is a pressing need to design and optimize the mass flow distribution device of Downcomer. In this paper, to obtain the specific parameters of structure matching the design values of mass flow rate, the finite element analysis was adopted, combined with the Nelder-Mead algorithm in the nonlinear programming. The results show that the mass flow distribution device with a multiple-port plate structure can achieve the purpose of the values of mass flow rate. Moreover, the mass flow rate is not so sensitive to the geometric parameters of these structures, which means more engineering margin. Based on this research, the detailed structural parameters and physical information about the distribution device were obtained, and the data from numerical tests can be used to build the proxy models to speed up transient analysis programs of FuSTAR.
Direct Contact Condensation Characteristics of Steam Injection into Cold-Water Pipe Under Rolling Condition
Authors: Wang Zhiwei , He Yanping , Duan Zhongdi , Huang Chao , Liu Shiwen
Published: April 2023

Direct contact condensation (DCC) is widely occurred in nuclear power systems and leads to undesired phenomena such as condensation-induced water hammer. For ocean nuclear power ships, DCC is inevitable in the passive heat removal system and influenced by sea conditions. In this paper, the characteristics of DCC under rolling conditions are analyzed. The numerical model of DCC is established based on computational fluid dynamics approach. The VOF model, SST k–ω turbulence model and the additional inertia force model are incorporated to describe the liquid-gas two-phase flow under the rolling motion. The condensation model based on surface renewal theory (SRT) is used to simulate steam-water DCC phenomenon. The simulation results are compared with the experimental data and show reasonable agreement. The effects of rolling motion on DCC for steam injection into a horizontal pipe filled with cold water are numerically investigated. The results show that the additional inertial forces and the average condensation rate increase with the increase of the rolling angle and frequency. The reverse flow of the seawater induced by rolling motion leads to the accumulation of the steam at the lower part of the pipe, resulting in a large pressure pulse. With the increase of rolling angle and frequency, the pressure pulse induced by DCC increases.
Study on the Influence of Stretch-Out Operation on the Deposition of Corrosion Products and Source Term Level in the Primary Circuit of Pressurized Water Reactor
Authors: Ruan Tianming , Mao Yulong
Published: April 2023

Corrosion products in the primary circuit of Pressurized Water Reactor (PWR) during operation will cause Chalk Rivers Unidentified Deposit (CRUD), increase the level of coolant source term and deposition source term outside the core, and then affect the normal operation of PWR and the radiation field during the shutdown overhaul. Stretch-Out (SO) operation is a flexible mode of reactor, which can improve the economy of reactor. In this paper, the theoretical model of CRUD and source term analysis for PWR is introduced, and the influence of SO operation on CRUD and source term level of PWR is studied. The calculation results show that SO operation can reduce the total amount of CRUD in PWR. However, the level of coolant source term rises at the initial stage of SO operation, and the level of coolant source term can be reduced by double discharge pumps running in this case. The deposition source term outside the reactor show a gradual increasing trend. The research results provide theoretical basis and data reference for CRUD and source term level control during SO operation in PWR.
Development of Heat Pipe Modeling Capabilities in a Fully-Implicit Solution Framework
Authors: Hu Guojun
Published: April 2023

One key aspect in analysis of heat pipe microreactors is the efficient modeling of heat pipes and its coupling with the solid reactor core. Various options exist for modeling of heat pipes. Most models require an explicit coupling between the vapor core, which brings in an additional layer of coupling when the heat pipe model is integrated into a system-level safety analysis model. This additional layer of coupling causes both convergence concern and computational burden in practice. This article aims at developing a new heat pipe modeling algorithm, where the heat pipe wall, wick, and vapor core are discretized and coupled in a monolithic fully-implicit manner. The vapor core will be modeled as a one-dimensional compressible flow with the capability of predicting sonic limit inherently; a two-dimensional axisymmetric heat conduction model will be used to model the heat pipe wall and wick region. The heat pipe wick and vapor core are coupled through a conjugate heat transfer interface. Eventually, the coupled system will be solved using the Jacobian-Free Newton-Krylov (JFNK) method. It is demonstrated that the new coupled system works well. Consideration of the vapor compressibility in the two-equation model allows more detailed representation of the vapor core dynamics while remains light-weight in terms of computational complexity. The new model is verified by an approximate analytical solution to the heat pipe vapor core and is validated by a sodium heat pipe experiment.
Verification of Solver for Coupled Simulation of Fluid and Fuel Pin in LFR Based on Openfoam
Authors: Ou Wenlan , Gong Zhengyu , Pan Qiwen , Zhang Ling , Dai Jianing , Gu Zhixing
Published: April 2023

The Computational Fluid Dynamics (CFD)-based thermal-hydraulics and safety analyses of Lead-based Fast Reactor (LFR) have attracted great attentions in recent years. Commercial CFD tools have been widely used in the 3D simulations of pool-type reactors owing to their powerful abilities in geometric modeling and meshing. Compared with the commercial CFD tools, OpenFOAM is a free open-source CFD code, which is more flexible to perform multi-physics coupling activities. In this paper, in order to develop a solver for simulating the coupled flow and heat transfer behaviors of fluid (coolant) and fuel pin in LFR, the fuel pin Heat Conduction (HC) model was coupled to the modified icoFoam solver of OpenFOAM. Verifications were conducted by the steady-state coupled simulation of fluid and fuel pin heat transfer behaviors, comparing with the MPC-LBE code which has been verified by the benchmarks for LFR fuel pin channel. The results simulated by the coupled solver proposed in this paper agreed well with the ones provided by the MPC-LBE code. This study lays a foundation for the further development of transient safety analysis code for LFR in our future work.
Monte Carlo Simulation and Analysis of Specified Element Samples by Nuclear Resonance Fluorescence Detection
Authors: Zhang Chen , Zheng Yu-Lai , Wang Qiang , Li Yong , Li Zi-Han
Published: April 2023

The detection of explosives and drugs in large cargo distribution centers such as customs and logistics stations has a great effect on preventing smuggling crimes and terrorist incidents. However, the relatively thick shielding of container cargo makes the material composition information obtained by conventional detection methods such as X-ray transmission detection and imaging technology very limited. Nuclear Resonance Fluorescence (NRF) is an emerging nondestructive assay technology that uses the specific resonance energy of nuclides to identify unknown nuclides, which can be used to detect and analyze the isotopic composition of the inspected cargo. In this paper, according to the theoretical analysis of NRF, Geant4 is used to build the NRF backscatter detection model, the collimator structure of the electron accelerator and the background shield of the NRF signal are optimized and calculated, and the NRF process with 12C as the target element is simulated and calculated. The results show that the simulated characteristic energy spectrum of NRF signal is consistent with the theory, the designed background shielding scheme meets the needs of NRF signal identification and detection, and the simulated signal-to-noise ratio data provides the basis for the experiment.
Study on a Non-collecting Atmospheric Radon Concentration Measurement System
Authors: Tang Chuanfeng , Ge Liangquan , Guo Shengliang , Deng Zhipeng , Li Jin
Published: April 2023

Radon in the atmosphere is an important tracer in meteorology and geology and an important index of environmental radioactivity level evaluation. In this paper, NaI (Tl) scintillator detector was developed to directly measure radon concentration in the atmosphere, and a mathematical model of atmospheric radon gamma measurement was proposed, which solved the technical problem of online real-time monitoring of atmospheric radon concentration. It has important scientific and practical value.

In this paper, the characteristic gamma peaks of radon daughters 214Bi (609.31 keV) and 214Pb (351.92 keV) are respectively selected to calculate the radon concentration in the atmosphere. During the measurement period, the variation trend of radon concentration is the same as the theory, which suggests a higher concentration in the morning and a lower in the evening. Finally, the experimental measurement results were compared with the RAD7 radon measuring instrument. The error range of this detection system is 79.73% smaller than that of RAD7 on average, and its detection limit reaches 0.29 Bq/m3 with a 30-min-measurement at room temperature. This paper proves that it is feasible to directly measure the activity concentration of radon in the atmosphere. The atmospheric radon measurement method proposed in this paper can accurately obtain the concentration of atmospheric radon and has the advantages of convenience, large measuring range, low detection limit, and online measurement.
Correlating IASCC Growth Rate Data to Some Key Parameters for Austenitic Stainless Steels in High Temperature Water
Authors: Xie Caibo , Nie Songhan , Tao Yiqi , Lu Zhanpeng
Published: April 2023

Austenitic stainless steels have been widely used for fabricating reactor core-internal components in PWRs due to its high strength, ductility and fracture toughness. The accelerated failure or degradation of austenitic stainless steel represented by IASCC has become one of the key problems affecting the safe and efficient operation of reaction core-internal in PWR nuclear power plants. IASCC is generally divided into three stages: crack initiation, crack propagation and instable fracture. Among the three stages, the crack initiation stage would occupy the major service time, the crack growth stage is featured by quasi-steady crack propagation at a certain rate, and the instable fracture stage should be avoided. Stress intensity factor K at the crack tip is often used to represent the mechanical driving force for SCC as well as IASCC.

In this paper, SCC crack growth rate (CGR) data of austenitic stainless steels irradiated in high temperature water were compiled and reanalyzed to evaluate the influence of key parameters such as radiation dose and mechanical properties on IASCC sensitivity and crack growth rate of these materials in PWR nuclear power plant environment. The CGR-K curves of the irradiated materials were also analyzed. The effects of low, medium and high doses of neutron irradiation are compared, and the analysis process is illustrated with examples. In the research process, abnormal CGR and K of materials under a specific irradiation dose was found, so this phenomenon was analyzed. The CGR data and irradiation dose of austenitic stainless steel in different K range were analyzed. And proposed a way to judge the type of change:type I, type II and type III. Finally, the yield strength of the material under the same irradiation dose was found, and combined with other research data, it was further demonstrated that the neutron irradiation dose had a significant effect on the crack growth rate.
Group Constants Generation Based on NECP-MCX Monte Carlo Code
Authors: Qin Shuai , He Qingming , Bai Jiahe , Dong Wenchang , Cao Liangzhi , Wu Hongchun
Published: April 2023

The reliability of few-group constants generated by lattice physics calculation is significant for the accuracy of the conventional two-step method in neutronics calculation. The deterministic method is preferred in the lattice calculation due to its efficiency. However, it is difficult for the deterministic method to treat the resonance self-shielding effect accurately and handle complex geometries. Compared to the deterministic method, the Monte Carlo method has the characteristics of using continuous-energy cross section and the powerful capability of geometric modeling. Therefore, the Monte Carlo particle transport code NECP-MCX is extended in this study to generate assembly-homogenized few-group constants. The cumulative migration method is adopted to generate the accurate diffusion coefficient and the leakage correction is performed using the homogeneous fundamental mode approximation. For the verification of the generated few-group constants, a code sequence named MCX-SPARK is built based on NECP-MCX and a core analysis code SPARK to perform the two-step calculation. The physics start-up test of the HPR1000 reactor is simulated using the MCX-SPARK sequence. The results from MCX-SPARK agree well with the results from the design report and a deterministic two-step code Bamboo-C. It is concluded that the NECP-MCX has the ability to generate accurate few-group constants.
Design of Radioactive Waste Classification and Detection System for Nuclear Facility Decommissioning
Authors: Chang Kang , Cheng Guangming , Zeng Jinwei , Xie Wenzhang , Shan Chenyu , Lei Qingxin , Huang Jia , Liu Feng , Liu Xiajie , Li Li
Published: April 2023

The most important indicator of the radioactive waste classification and detection system is its identifiable minimum activity of low level radioactive waste, that is, the lower detection limit. In order to design a low level and very low level waste classification and detection system that can perform large-scale and rapid measurement, and explore the influence of various factors on the low limit of detection, this paper establishes the layout model of the detection unit of the classification detection system by Monte Carlo method to simulate the number of NaI crystals, the density of the detected object, the distance between the detection crystal and the detected object, the distance between the adjacent measured waste and the measurement time, etc. Meanwhile this paper analyzes the characteristics of the low limit of detection, and performs operations research analysis based on the principle of being able to detect radioactive waste with specific activity of not less than 0.1 Bq·g−1, maximizing the shielding effect and optimizing the shielding weight, and designs a low level and very low level waste classification and detection system that can measure radioactive waste which density is not less than 0.25 g/cm3 and which specific activity is not less than 0.1 Bq·g−1.
Research on the Alarm Threshold for Steam Generator Tube Leak Monitoring of Small Modular Reactor
Authors: Xia Ming-ming , Wang Jun-long , Xu Tao , Huang Bo-chen , Zhu Jian-ping , Wu Yi-rui , Miao Jian-xin , Chen Xin
Published: April 2023

On the basis of fully learning from the existing principles of leak monitoring alarm thresholds setting of the steam generator tube in pressurized water reactor nuclear power plants, the principle of setting for N-16 leak monitoring alarm thresholds of steam generator tube in small modular reactors is proposed, and the N-16 monitoring alarm thresholds are given. The calculation method for total gamma count rate of steam generator tube leak monitoring alarm thresholds of the small modular reactor is established, and the total gamma count rate under the condition of the leak corresponding to the N-16 monitoring alarm thresholds is calculated to guide the leak monitoring total gamma alarm thresholds set.