bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of a novel Fe‐MOF as the flame retardant synergist and its application in polystyrene
Authors: Jin Xiaodong , Wu Xinyi , Liu Qinyong , Sun Shibing , Cui Suping , Zhang Sheng , Chen Chen
Published: November 2023

In this work, a metal organic framework (Fe‐MOF) with the effect of absorbing toxic gases and good compatibility was synthesized by chelating a novel organic ligand contained carbonization groups (reacted by tris(hydroxymethyl) aminomethane and 1,4‐piperazine dialdehyde) with iron salt. Then, it was used as the synergist to improve the efficiency of intumescent flame retardant (IFR) within polystyrene (PS) substrate. With the addition of 20% IFR and 2% Fe‐MOF, the obtained PS composites exhibited a limiting oxygen index (LOI) value of 28.3% and a UL rating of V‐0. Moreover, the peak heat release rate (pHRR), total heat release (THR), and total smoke production (TSP) of PS composites were decreased by 77.6%, 35.2%, and 33.7%, respectively. According to the mechanism analysis, it was found that Fe‐MOF mainly acted in the condensed phase, contributing to the existence of dense char residues with the presence of IFR system. In addition, the good compatibility of organic ligand in Fe‐MOF with PS substrate could partially alleviate the deterioration of mechanical properties due to the addition of IFR. For PS‐20%IFR/2%Fe‐MOF, the impact strength was improved from 1.7 kJ/m2 (PS‐22%IFR) to 2.2 kJ/m2, the tensile strength was also increased from 21.3 MPa (PS‐22%IFR) to 22.4 MPa.
A critical note on memory‐type charts with the Brownian statistic
Authors: Haq Abdul
Published: November 2023

In the paper, we conduct an assessment of the conditional expected delay (CED) profiles of the EWMA, CUSUM, and dual CUSUM charts based on a statistic linked to Brownian motion. The study reveals a noteworthy observation: the CED curves for these control charts may exhibit an increasing trend over time. Moreover, in a steady‐state scenario, it becomes evident that these control charts could be outperformed by their established counterparts.
Identifying ice‐jam flooding events through the application of dendrogeomorphological methods
Authors: Lubiniecki Teagan , Laroque Colin P. , Lindenschmidt Karl‐Erich
Published: November 2023

In this research, we explore whether a dendrogeomorphological assessment of tree scarring can accurately summarize past ice‐jam flooding events occurring at a given reach of a river. A sample site was chosen with a history of ice‐jam flooding located in close proximity to a river gauge station. Samples were collected along a 200‐m stretch of riverbank to capture the variation in elevations and possible different ice‐jam flooding events. Disk samples were collected from trees with visual scarring evidence that indicated they had endured a past ice‐jam event. Tree cores from an adjacent stand were collected to create a master chronology for each of the sampled species. Tree disks and cores were analyzed under a microscope using a Velmex stage system, then visually and statistically crossdated using the program COFECHA. Based on the last year of tree growth, years of individual injury events were established. The years of injury event dates were compared against the years of highest instantaneous maximum water elevations from gauged river data. The two data sets correlated, as the years with the highest recorded injury event dates were also the years of highest instantaneous water level elevations. The most common years of injury event dates were directly reflected in the top 5 years of the highest river instantaneous water level elevations. In addition, the year of 2020 had the highest water elevations in the past 27 years, which was again reflected in the dendrogeomorphological data as the injury event year of 2020 was recorded on over 90% of the sampled tree disks. The correlation found between the gauged river data and the dendrogeomorphological data strongly suggests that past ice‐jam flooding event dates can accurately be determined through the analysis of trees in riverbank stretches that have been impacted by ice jams. The relationship of the gauged river data to the dendrogeomorphological data will therefore allow researchers to determine ice‐jam site histories in remote areas where no gauged data exist. The site histories can provide information such as the years or heights that past ice‐jam flooding occurred, which could then be used in ice‐jam flooding hazard assessments.
Development and validation of high‐performance thin layer chromatographic method for concurrent estimation of dapagliflozin and vildagliptin in combined tablet
Authors: Sen Ashim Kumar , Khatariya Satish B , Sen Dhanya B , Maheshwari Rajesh A , Akabari Ashok H , Velmurugan Ramaswamy
Published: November 2023

Enhanced glycemic regulation in individuals with diabetes mellitus can be achieved using a fixed‐dose combination of dapagliflozin (10 mg) and vildagliptin (100 mg) in tablet. The primary objective of this research was to develop and validate a high‐performance thin layer chromatographic methodology for accurately measuring the quantities of dapagliflozin and vildagliptin in combined tablet formulation. The methodology involved using aluminum plates layered with silica gel 60F254, and the solvent system comprised of acetonitrile, benzene, and glacial acetic acid (9:1:2 v/v/v). Densitograms were scanned at a wavelength of 210 nm. The linearity of the procedure was established in the series of 200–2500 ng/band for dapagliflozin and 2000–25000 ng/band for vildagliptin, with correlation coefficients (r2) of 0.9931 and 0.9954, correspondingly. The method demonstrated good sensitivity, with detection limits of 21.07 ng/band for dapagliflozin and 154.97 ng/band for vildagliptin; quantification limits of 63.84 ng/band for dapagliflozin and 469.60 ng/band for vildagliptin. The methodology was found to be precise (% relative standard deviation of peak area <2) and accurate (recovery between 97% and 103%). Proposed method was found to be superior and capable of overcoming the shortcomings of previously reported methods for the assessment of dapagliflozin and vildagliptin in combined formulation.
Differential patterns of lysosomal dysfunction are seen in the clinicopathological forms of primary progressive aphasia
Authors: Swift Imogen J. , Sjödin Simon , Gobom Johan , Brinkmalm Ann , Blennow Kaj , Zetterberg Henrik , Rohrer Jonathan D. , Sogorb-Esteve Aitana
Published: November 2023

Increasing evidence implicates endo-lysosomal dysfunction in frontotemporal dementia (FTD). 18 proteins were quantified using a mass spectrometry assay panel in the cerebrospinal fluid of 36 people with the language variant of FTD, primary progressive aphasia (PPA) (including 13 with non-fluent variant (nfvPPA), 11 with semantic variant (svPPA), and 12 with logopenic variant (lvPPA)) and 19 healthy controls. The concentrations of the cathepsins (B, D, F, L1, and Z) as well as AP-2 complex subunit beta, ganglioside GM2 activator, beta-hexosaminidase subunit beta, tissue alpha l-fucosidase, and ubiquitin were decreased in nfvPPA compared with controls. In contrast, the concentrations of amyloid beta A4 protein, cathepsin Z, and dipeptidyl peptidase 2 were decreased in svPPA compared with controls. No proteins were abnormal in lvPPA. These results indicate a differential alteration of lysosomal proteins in the PPA variants, suggesting those with non-Alzheimer’s pathologies are more likely to show abnormal lysosomal function.
Effect of Nozzle Parameters on the Cooling Conditions in the Secondary Cooling Zone of a Slab Caster
Authors: Taferner Matthias , Laschinger Julian , Bernhard Christian , Bernhard Michael , Ilie Sergiu
Published: November 2023

The following contribution focuses on the secondary cooling zone of a slab caster, analyzing the effects of nozzle parameters on cooling conditions. The research group employs experimental measurements, including the Nozzle Measuring Stand (NMS), to determine local heat transfer coefficients (HTC) and water distribution. These measurements are crucial for accurately setting the boundary conditions in the simulation. The implementation of these boundary conditions is realized by an Exponential Gaussian Process Regression (EGPR) to predict HTC values. The results highlight the importance of an accurate HTC assessment in regions with overlapping sprays. The developed methodology aids in enhancing the precision of simulations for continuous casting processes, contributing to a better product quality and process efficiency using the non-commercial software platform “m2CAST”.
Atypical neurocognitive functioning in children and adolescents with obsessive–compulsive disorder (OCD)
Authors: Uhre Camilla Funch , Ritter Melanie , Jepsen Jens Richardt Møllegaard , Uhre Valdemar Funch , Lønfeldt Nicole Nadine , Müller Anne Dorothee , Plessen Kerstin Jessica , Vangkilde Signe , Blair Robert James , Pagsberg Anne Katrine
Published: November 2023

Atypical neurocognitive functioning has been found in adult patients with obsessive–compulsive disorder (OCD). However, little work has been done in children and adolescents with OCD. In this study, we investigated neurocognitive functioning in a large and representative sample of newly diagnosed children and adolescents with OCD compared to non-psychiatric controls. Children and adolescents with OCD (n = 119) and non-psychiatric controls (n = 90) underwent psychopathological assessment, intelligence testing, and a neurocognitive test battery spanning cognitive flexibility, planning and decision-making, working memory, fluency, and processing speed. The MANOVA main effect revealed that children and adolescents with OCD performed significantly worse than the control group (p < .001, $${\eta }_{p}^{2}$$

η

p

2

= 0.256). Atypical patient performance was particularly found for indices of cognitive flexibility, decision-making, working memory, and processing speed. We found no evidence of differences in planning or fluency. Moreover, we found no significant associations between neurocognitive performance and OCD symptom severity or comorbidity status. Our results indicate that children and adolescents with OCD show selective atypical neurocognitive functioning. These difficulties do not appear to drive their OCD symptoms. However, they may contribute to lifespan difficulties and interfere with treatment efficacy, an objective of our research currently.
Antibiotic use in pediatric acute care hospitals: an analysis of antibiotic consumption data from Germany, 2013–2020
Authors: Freudenhammer Mirjam , Hufnagel Markus , Steib-Bauert Michaela , Mansmann Ulrich , de With Katja , Fellhauer Matthias , Kern Winfried V.
Published: November 2023

Background

Antimicrobial stewardship (AMS) programs are effective tools for improving antibiotic prescription quality. Their implementation requires the regular surveillance of antibiotic consumption at the patient and institutional level. Our study captured and analyzed antibiotic consumption density (ACD) for hospitalized pediatric patients.

Method

We collected antibacterial drug consumption data for 2020 from hospital pharmacies at 113 pediatric departments of acute care hospitals in Germany. ACD was calculated as defined daily dose (DDD, WHO/ATC Index 2019) per 100 patient days (pd). In addition, we analyzed the trends in antibiotic use during 2013–2020.

Results

In 2020, median ACD across all participating hospitals was 26.7 DDD/100 pd, (range: 10.1–79.2 DDD/100 pd). It was higher at university vs. non-university hospitals (38.6 vs. 25.2 DDD/100 pd, p < 0.0001). The highest use densities were seen on oncology wards and intensive care units at university hospitals (67.3 vs. 38.4 DDD/100 pd). During 2013–2020, overall ACD declined (− 10%) and cephalosporin prescriptions also decreased (− 36%). In 2020, cephalosporins nevertheless remained the most commonly dispensed class of antibiotics. Interhospital variability in cephalosporin/penicillin ratio was substantial. Antibiotics belonging to WHO AWaRe “Watch” and “Reserve” categories, including broad-spectrum penicillins (+ 31%), linezolid (+ 121%), and glycopeptides (+ 43%), increased over time.

Conclusion

Significant heterogeneity in ACD and prescription of different antibiotic classes as well as high prescription rates for cephalosporins and an increased use of reserve antibiotics indicate improvable antibiotic prescribing quality. AMS programs should urgently prioritize these issues to reduce antimicrobial resistance.
Energetic Electrons Near Europa From Juno JEDI Data
Authors: Paranicas C. , Mauk B. H. , Clark G. , Kollmann P. , Westlake J. , Hibbitts K. , Nordheim T. , Hand K. , Brennan M. , Connerney J. E. P. , Bolton S.
Published: November 2023

Optical remote sensing observations have suggested that the top layer of Europa's icy surface is heavily affected by external weathering agents. To model and understand these effects, it is necessary to characterize the environment as fully as possible. In this paper, we focus on one agent in the environment (energetic electrons). We show Juno electron data from its 2022 Europa flyby and other time periods. While the Juno sensor used here (Jupiter Energetic Particle Detector Instrument) was not designed to obtain high quality electron data in an intense radiation environment, it is possible to extract information such as how Europa blocks energetic particles from accessing some of the surrounding space. The decrease in charged particle flux in Europa's wake provides an upper limit on the precipitation fluxes of the same particles. We also report that electron pitch angle distributions near Europa for the single energy channel considered here are time variable and not isotropic.
Whole brain network effects of subcallosal cingulate deep brain stimulation for treatment-resistant depression
Authors: Cha Jungho , Choi Ki Sueng , Rajendra Justin K. , McGrath Callie L. , Riva-Posse Patricio , Holtzheimer Paul E. , Figee Martijn , Kopell Brian H. , Mayberg Helen S.
Published: November 2023

Ongoing experimental studies of subcallosal cingulate deep brain stimulation (SCC DBS) for treatment-resistant depression (TRD) show a differential timeline of behavioral effects with rapid changes after initial stimulation, and both early and delayed changes over the course of ongoing chronic stimulation. This study examined the longitudinal resting-state regional cerebral blood flow (rCBF) changes in intrinsic connectivity networks (ICNs) with SCC DBS for TRD over 6 months and repeated the same analysis by glucose metabolite changes in a new cohort. A total of twenty-two patients with TRD, 17 [15 O]-water and 5 [18 F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) patients, received SCC DBS and were followed weekly for 7 months. PET scans were collected at 4-time points: baseline, 1-month after surgery, and 1 and 6 months of chronic stimulation. A linear mixed model was conducted to examine the differential trajectory of rCBF changes over time. Post-hoc tests were also examined to assess postoperative, early, and late ICN changes and response-specific effects. SCC DBS had significant time-specific effects in the salience network (SN) and the default mode network (DMN). The rCBF in SN and DMN was decreased after surgery, but responder and non-responders diverged thereafter, with a net increase in DMN activity in responders with chronic stimulation. Additionally, the rCBF in the DMN uniquely correlated with depression severity. The glucose metabolic changes in a second cohort show the same DMN changes. The trajectory of PET changes with SCC DBS is not linear, consistent with the chronology of therapeutic effects. These data provide novel evidence of both an acute reset and ongoing plastic effects in the DMN that may provide future biomarkers to track clinical improvement with ongoing treatment.
Tumor cell-released kynurenine biases MEP differentiation into megakaryocytes in individuals with cancer by activating AhR–RUNX1
Authors: Zhou Li , Wu Dongxiao , Zhou Yabo , Wang Dianheng , Fu Haixia , Huang Qiusha , Qin Guohui , Chen Jie , Lv Jiadi , Lai Shaoyang , Zhang Huafeng , Tang Ke , Ma Jingwei , Fiskesund Roland , Zhang Yi , Zhang Xiaohui , Huang Bo
Published: November 2023

Tumor-derived factors are thought to regulate thrombocytosis and erythrocytopenia in individuals with cancer; however, such factors have not yet been identified. Here we show that tumor cell-released kynurenine (Kyn) biases megakaryocytic–erythroid progenitor cell (MEP) differentiation into megakaryocytes in individuals with cancer by activating the aryl hydrocarbon receptor–Runt-related transcription factor 1 (AhR–RUNX1) axis. During tumor growth, large amounts of Kyn from tumor cells are released into the periphery, where they are taken up by MEPs via the transporter SLC7A8. In the cytosol, Kyn binds to and activates AhR, leading to its translocation into the nucleus where AhR transactivates RUNX1, thus regulating MEP differentiation into megakaryocytes. In addition, activated AhR upregulates SLC7A8 in MEPs to induce positive feedback. Importantly, Kyn–AhR–RUNX1-regulated MEP differentiation was demonstrated in both humanized mice and individuals with cancer, providing potential strategies for the prevention of thrombocytosis and erythrocytopenia.
Continuous deep brain stimulation of the nucleus accumbens reduces food intake but does not affect body weight in mice fed a high-fat diet
Authors: Hounchonou Harold F. , Tang Hui , Paulat Raik , Kühn Andrea , Spranger Joachim , van Riesen Christoph , Maurer Lukas
Published: November 2023

Obesity is an enormous health problem, and many patients do not respond to any of the available therapies. Deep brain stimulation (DBS) is currently investigated as a potential treatment for morbid obesity. In this study, we tested the hypothesis that high-frequency DBS targeting the nucleus accumbens (NAc) shell region reduces food intake and weight gain in mice fed a high-fat diet. We implanted male C57BL/6J mice with bilateral electrodes and a head-mounted microstimulator enabling continuous stimulation for up to 5 weeks. In successfully operated animals (n = 9 per group, high-frequency vs. sham stimulation), we investigated immediate and long-term stimulation effects on metabolic and behavioral phenotypes. Here we show that stimulation acutely induced a transient reduction in energy expenditure and locomotor activity but did not significantly affect spontaneous food intake, social interaction, anxiety or exploratory behaviors. In contrast, continuous stimulation over 5 weeks led to a decrease in food intake and thigmotaxis (the tendency to stay near walls in an open lit arena). However, chronic stimulation did not substantially change weight gain in mice fed a high-fat diet. Our results do not support the use of continuous high-frequency NAc shell DBS as a treatment for obesity. However, DBS can alter obesity-related parameters with differing short and long-term effects. Therefore, future research should employ time and context-sensitive experimental designs to assess the potential of DBS for clinical translation in this area.
Simultaneous recognition of dopamine and uric acid in real samples through highly sensitive new electrode fabricated using ZnO/carbon quantum dots: bio-imaging and theoretical studies
Authors: Tecuapa-Flores Eduardo D. , Palacios-Cabrera Cristian B. , Santiago-Cuevas Alan J. , Hernández José G. , Narayanan Jayanthi , Thangarasu Pandiyan
Published: November 2023

Dopamine (DA) and uric acid (UA), vital components, cause several health problems if their concentrations are altered; so, the determination of DA and UA is turned to be essential in real samples.
Enhancement of cryopreservation with intracellularly permeable zwitterionic polymers
Authors: Yamasaki Ryota , Rajan Robin , Matsumura Kazuaki
Published: November 2023

Intracellular permeation of zwitterionic polymers was shown to improve cell recovery after freezing and thawing.
Effects of defects in a 4H-SiC material on the breakdown behavior of a Schottky barrier diode
Authors: Zhang Xuexia , Lou Yanfang , Gong Tuochen , Wang Guangming , Yao Jing , Yong Qing , Peng Tonghua , Yang Jian , Liu Chunjun
Published: November 2023

Substrate TSDs propagate into an epilayer and cause breakdown holes.
Fine-tuning synthesis of a novel CuI/CuII mixed-valence coordination polymer
Authors: Sie Shu-Ling , Kamal Surabhi , Lu Zong-Zhan , Wei Ling-Fang , Luo Tzuoo-Tsair , Liu Yen-Hsiang , Chang Chao-Wan , Chi Kai-Ming , Lu Kuang-Lieh
Published: November 2023

An excellent example of the design, synthesis, and crystal engineering of mixed-valence compounds is reported.
Morphological control for high proton conduction in robust Co3O4-diethylmethylamine (metal–organic framework) membrane
Authors: Yadav Gargi , Jha Pardeep K. , Jha Priyanka A. , Singh Parvin K. , Choudhary Suman Roy , Singh Prabhakar
Published: November 2023

Morphological engineering results in a robust MOF membrane with high protonic conductivity of 0.0286 S cm−1 (transference number >0.99), mechanical strength and catalytic activity.
The ionization energy of α-sexithiophene and p-sexiphenyl in 2D and 3D thin films grown on silicon oxide surfaces
Authors: Eguchi Keitaro , Murata Hideyuki
Published: November 2023

The evolution of the ionization energy of rod-like π-conjugated molecules in thin films strongly depends on the molecular arrangements of the topmost layers.
Highly efficient β-lactamase assay applying poly-dimethylacrylamide-based surface functionalization with β-lactam antibiotics and β-lactamase inhibitors
Authors: Rentschler Simone , Borgolte Max , Filbert Alexander , Laufer Stefan , Deigner Hans-Peter
Published: November 2023

Immobilization of antibiotics to surfaces via PDMA by UV-crosslinking providing a highly efficient diagnostic β-lactamase assay. The method is transferable to different substrate materials and devices as well as antibiotics and chemical substances.
A simplified and cost-effective detection of cancer bio-markers using BODIPY and surfactant-templated fluorogenic self-assembly
Authors: Sarkar Soumyadeep , Gorai Sudip , Potnis Akhilesh , Jonnalgadda Padma Nilaya , Mula Soumyaditya , Chakraborty Goutam
Published: November 2023

This study presents a novel approach for fluorescence-based spermine sensing, using a laboratory synthesized distyryl BODIPY dye in combination with a widely available and inexpensive anionic surfactant, SDS.
Advancing IR in Underserved Regions: Interventional Radiology Simulation Near and Far
Authors: Koech Cornelius K. , Rivera Victor I. , Anton Kevin , Dixon Robert G.
Published: November 2023

Simulation facilitates learning by imitating real-world systems or processes utilizing educational tools and models. Various fields, including business, aviation, and education use simulation for training. In healthcare, simulation provides trainees opportunities to develop procedural skills in a safe environment, building their understanding through hands-on interactions and experiences rather than passive didactics. Simulation is classified into low, medium, and high fidelity, based on how closely it mimics real-life experience. Its use in education is a valuable adjunct to instructional support and training with multiple potential benefits. Interventional radiology (IR) trainees can build technical and clinical proficiency prior to working directly on a patient. Simulation promotes experiential learning, constructivist learning, and student centeredness, thus giving students control over their learning and knowledge acquisition. More recently, the creative use of remote simulation has augmented traditional virtual didactic lectures, thereby further engaging international learners and enhancing remote collaboration. Despite the challenges to implementation, the addition of simulation in IR education is proving invaluable to supporting trainees and physicians in underserved regions.
Development of sweep frequency ultrasonic interferometer for high precision velocity measurement in liquids
Authors: Dhiman Nitin , Sharma Sahil , Piyush  , Kumar Bishan , Yadav Sanjay , Dubey P. K.
Published: November 2023

An ultrasonic interferometer with variable separation between the transducer and reflector is widely used for the measurement of ultrasonic propagation velocity in liquids. The inherent limitation of such an interferometer is due to the mechanical movement of its reflector for ultrasonic wavelength measurement in a liquid medium. It is observed that the ultrasonic velocity measurement precision is adversely affected at higher frequencies compared to lower ones. For instance, in our experimentation, a standard deviation of ±21.5 m/s (±1.43%) was obtained for velocity measurement at 1.84 MHz with the consideration of two consecutive maxima, which increases drastically to ±76.8 m/s (±5.12%) at 9.4 MHz. These measurements can significantly be improved by considering many maxima and averaging for wavelength estimation. However, it still requires design attention and improvement, particularly for higher frequencies. In this article, a sweep-frequency based ultrasonic interferometer design with a fixed separation for liquid characterization is proposed and described. This technique overcomes the limitations of mechanical movement systems and also provides a better and uniform precision for lower as well as higher frequencies. The functionality of the developed sweep frequency method was tested in water, carbon tetrachloride, ethylene glycol, and glycerol, which shows good agreement with literature values. The velocity measurement in double distilled water by the developed technique at 1 Hz sweep resolution has shown an improved standard deviation of ±0.74 m/s (±0.05%) at 9.4 MHz.
Winding number statistics for chiral random matrices: Averaging ratios of parametric determinants in the orthogonal case
Authors: Hahn Nico , Kieburg Mario , Gat Omri , Guhr Thomas
Published: November 2023

We extend our recent study of winding number density statistics in Gaussian random matrix ensembles of the chiral unitary (AIII) and chiral symplectic (CII) classes. Here, we consider the chiral orthogonal (BDI) case which is the mathematically most demanding one. The key observation is that we can map the topological problem on a spectral one, rendering the toolbox of random matrix theory applicable. In particular, we employ a technique that exploits supersymmetry structures without reformulating the problem in superspace.
Non–uniform decay of solutions to the incompressible magneto–micropolar fluids with/without magnetic diffusion and spin viscosity
Authors: Wu Wanping , Zhang Yinghui
Published: November 2023

We are concerned with the long time behavior of solutions to the incompressible magneto–micropolar fluids with/without magnetic diffusion and spin viscosity in two and three dimensions. When the magnetic diffusion is absent, we show that L2–norm of fluid velocity and micro–rotational velocity vanishes and L2–norm of the magnetic field converges to a non–negative constant as time tends to infinity. Moreover, when both magnetic diffusion and spin viscosity are present and the initial data belongs to L2, we prove that the solutions decay to zero without a rate, and this non–uniform decay is optimal. The proofs are based on Fourier splitting method, low–frequency and high–frequency decomposition techniques and delicate energy estimates.
Self-consistent coupling of JOREK and CARIDDI: On the electromagnetic interaction of 3D tokamak plasmas with 3D volumetric conductors
Authors: Isernia N. , Schwarz N. , Artola F. J. , Ventre S. , Hoelzl M. , Rubinacci G. , Villone F. ,   JOREK Team
Published: November 2023

The self-consistent electromagnetic integration of tokamak plasma magnetohydrodynamic (MHD) models with external conductors is considered in this manuscript. We integrate the extended MHD code JOREK and the eddy current code CARIDDI, via a scheme based on the virtual casing principle enabling two-way coupled fully implicit simulations. The robustness of this new integrated tool is validated against JOREK-STARWALL and CarMa0NL simulations for vertical displacement events in a simplified ASDEX Upgrade-like geometry and for n = 1 tearing modes in a circular high-aspect-ratio tokamak. The impact of 3D wall structures on the plasma evolution is highlighted introducing ports at different locations of a simplified axisymmetric wall and characterizing its effect on the plasma evolution. In addition to realistically capturing the 3D interactions between plasma and wall structures, the coupled codes will allow in the future 1:1 comparisons to experiments using virtual magnetic diagnostics that capture screening effects accurately.
Impact of environmental oxygen on nanoparticle formation and agglomeration in aluminum laser ablation plumes
Authors: Kautz Elizabeth J. , Zelenyuk Alla , Gwalani Bharat , Olszta Matthew J. , Phillips Mark C. , Manard Manuel J. , Kimblin Clare W. , Harilal Sivanandan S.
Published: November 2023

The role of ambient oxygen gas (O2) on molecular and nanoparticle formation and agglomeration was studied in laser ablation plumes. As a lab-scale surrogate to a high explosion detonation event, nanosecond laser ablation of an aluminum alloy (AA6061) target was performed in atmospheric pressure conditions. Optical emission spectroscopy and two mass spectrometry techniques were used to monitor the early to late stages of plasma generation to track the evolution of atoms, molecules, clusters, nanoparticles, and agglomerates. The experiments were performed under atmospheric pressure air, atmospheric pressure nitrogen, and 20% and 5% O2 (balance N2), the latter specifically with in situ mass spectrometry. Electron microscopy was performed ex situ to identify crystal structure and elemental distributions in individual nanoparticles. We find that the presence of ≈20% O2 leads to strong AlO emission, whereas in a flowing N2 environment (with trace O2), AlN and strong, unreacted Al emissions are present. In situ mass spectrometry reveals that as O2 availability increases, Al oxide cluster size increases. Nanoparticle agglomerates formed in air are found to be larger than those formed under N2 gas. High-resolution transmission electron microscopy demonstrates that Al2O3 and AlN nanoparticle agglomerates are formed in both environments; indicating that the presence of trace O2 can lead to Al2O3 nanoparticle formation. The present results highlight that the availability of O2 in the ambient gas significantly impacts spectral signatures, cluster size, and nanoparticle agglomeration behavior. These results are relevant to understanding debris formation in an explosion event, and interpreting data from forensic investigations.
Effects of flow conditions on the cavitation characteristics of viscous oil around a hydrofoil
Authors: Guo Meng , Liu Cheng , Ke Zhifang , Yan Qingdong , Zuo Zhengxing , Khoo Boo Cheong
Published: November 2023

Viscous oils, which are media commonly used for fluid power transmission, are characterized by high velocities, temperatures, and pressures when working in fluid components and mechanics. The transient nature of viscous oil makes it susceptible to complex operating conditions, which result in cavitation phenomena and can threaten the normal operation and safety of machinery and components. In this study, a three-dimensional computational fluid dynamics model that accounts for cavitation was developed to study the cavitation characteristics, formation conditions, and development of cavitating flow in viscous oil around a hydrofoil under various flow conditions. Moreover, a visual experimental system in which viscous oil flowed around the hydrofoil was proposed and developed to investigate the cavitation properties with regard to various flow conditions. Both numerical results and experimental data indicated that cavitation occurred on the suction surface of the hydrofoil head, and the cavitation characteristics in viscous oil are significantly influenced by the flow conditions. The maximum vapor volume change rate for the degree of effects on cavitation in viscous oil by flow conditions was calculated to be 1.78 cm3/(m/s), −130.66 cm3/MPa, 0.16 cm3/°C, and 4.52 cm3/°, respectively. Low velocities, high pressures, low temperatures, and small impact angles were proved to be able to suppress cavitation. This study provides a research method, an experimental mean, and data support for cavitation flow of viscous fluids, especially oil. It has significant engineering application significance for the development of fluid machinery.
Effect of surface radiation on double diffusion convection in a low Mach number compressible gaseous mixture (H2–air)
Authors: Hamimid Saber , Fenni Manel , Guellal Messaoud
Published: November 2023

This study aims to numerically investigate the effect of surface radiation on double diffusion convection in a low Mach number compressible gaseous mixture, specifically focusing on the H2–air system in a square cavity. The cavity is subjected to low horizontal temperature and concentration gradients and isolated from its flat walls. The mathematical model's equations were discretized using the finite volume method based on the semi-implicit method for pressure-linked equations revised algorithm for the pressure–velocity coupling. The radiosity method is employed to calculate the radiative heat exchange between the internal walls of the cavity. This work addresses a significant research gap by exploring the interplay between surface radiation, compressibility effects, and double diffusion convection. It makes a novel contribution to the field and has implications for combustion, astrophysics, and industrial heat exchange processes. Comparing the results with those obtained for a light gaseous mixture, the findings demonstrate that the presence of radiation considerably modifies the thermal, dynamic, and mass fields, as well as the thermophysical properties of the gaseous mixture in the case of heavy gaseous mixtures. These modifications can reach up to 20%.The outcomes of this study provide a foundation for further research and experimentation, with applications ranging from engineering to astrophysics.
Quantum and anharmonic effects in non-adiabatic transition state theory
Authors: Mulvihill Clayton R. , Georgievskii Yuri , Klippenstein Stephen J.
Published: November 2023

Quantitative descriptions of non-adiabatic transition rates at intermediate temperatures are challenging due to the simultaneous importance of quantum and anharmonic effects. In this paper, the interplay between quantum effects—for motion across or along the seam of crossing—and anharmonicity in the seam potential is considered within the weak coupling limit. The well-known expression for quantized 1-D motion across the seam (i.e., tunneling) in the linear terms approximation is derived in the thermal domain using the Lagrangian formalism, which is then applied to the case when tunneling is distributed along the seam of crossing (treating motion along the seam classically). For high-frequency quantum modes, a vibrationally adiabatic (VA) approach is developed that introduces to the non-adiabatic rate constant a factor associated with high-frequency wavefunction overlap; this approach treats the high-frequency motion along the seam quantum mechanically. To test these methodologies, the reaction N2O ↔ N2 + O(3P) was chosen. CCSD(T)-F12b/cc-pVTZ-F12 explorations of the 3A′-1A′ seam of N2O revealed that seam anharmonicity has a strong effect on the rate constant (a factor of ∼20 at 2000 K). Several quantum effects were found to be significant at intermediate/lower temperatures, including the quantum N–N vibration that was coupled with seam anharmonicity using the VA approach. Finally, a 1-D approximation to non-adiabatic instanton theory is presented to estimate the validity limit of the linear terms model at low temperatures (∼250 K for N2O). We recommend that the assumptions built into many statistical theories for non-adiabatic reactions—harmonic behavior, classical motion, linear terms, and weak coupling—should be verified on a case-by-case basis.
Probing adsorption of methane onto vanadium cluster cations via vibrational spectroscopy
Authors: Kozubal Justine , Heck Tristan , Metz Ricardo B.
Published: November 2023

Photofragment spectroscopy is used to measure the vibrational spectra of V2+(CH4)n (n = 1–4), V3+(CH4)n (n = 1–3), and Vx+(CH4) (x = 4–8) in the C–H stretching region (2550–3100 cm−1). Spectra are measured by monitoring loss of CH4. The experimental spectra are compared to simulations at the B3LYP+D3/6-311++G(3df,3pd) level of theory to identify the geometry of the ions. Multi-reference configuration interaction with Davidson correction (MRCI+Q) calculations are also carried out on V2+ and V3+. The methane binding orientation in V2+(CH4)n (n = 1–4) evolves from η3 to η2 as more methane molecules are added. The IR spectra of metal-methane clusters can give information on the structure of metal clusters that may otherwise be hard to obtain from isolated clusters. For example, the V3+(CH4)n (n = 1–3) experimental spectra show an additional peak as the second and third methane molecules are added to V3+, which indicates that the metal atoms are not equivalent. The Vx+(CH4) show a larger red shift in the symmetric C–H stretch for larger clusters with x = 5–8 than for the small clusters with x = 2, 3, indicating increased covalency in the interaction of larger vanadium clusters with methane.
Design and study of an eccentric wheel drive-based rotating piezoelectric energy harvester
Authors: Liu Xuejin , Wang Hongxin , Lv Xingqian , Zhang Limin , He Lipeng
Published: November 2023

A nonlinear rotating piezoelectric energy harvester (N-RPEH) driven by eccentric wheels is proposed to collect rotational energy in the environment. Driven by external rotational motion, an eccentric wheel converts rotational motion into linear motion and realizes electrical energy output through magnetic coupling. To increase the effectiveness of the equipment’s energy conversion process, this article aims to transform the rotational motion of an eccentric wheel into a linear motion of a motion board. The effects of the motion board’s length L, the cylindrical magnet’s height H, and the mass block M at the piezoelectric patch’s end on the output performance of N-RPEH are explained by theoretical modeling and simulation. Through theoretical analysis, simulation, and experiment, it is found that when L = 120 mm, H = 6 mm, and M = 5.0 g (medium mass), the output voltage reaches the maximum of 14.16 V. Under this parameter, N-RPEH can produce a maximum power of 7.0688 mW when the external resistance value is 2 kΩ. Application experiments show that N-RPEH can light up 60 light-emitting diodes. Therefore, the proposed N-RPEH can effectively collect rotational energy and has a wide range of potential applications in wireless sensor networks.
Analyzing the bending deformation of van der Waals-layered materials by a semi-discrete layer model
Authors: Akiyoshi Masao , Shimada Takahiro , Hirakata Hiroyuki
Published: November 2023

Van der Waals (vdW)-layered materials, such as graphite, exhibit unique mechanical properties owing to their structural and mechanical anisotropies. This study reports the development of a mechanical model that reproduces the characteristics of the nonlinear and reversible bending deformation of vdW-layered materials, while taking into account the microscopic mechanism of the discrete interlayer slips. The vdW-layered material was modeled as a stack of interacting discrete deformable layers (semi-discrete layer model), and the interlayer interaction was modeled using a cohesive zone model that reproduced the localized interlayer slip. Using the finite-element method, out-of-plane bending deformation analyses were performed on the cantilevers of the highly oriented pyrolytic graphite (HOPG) and MoTe2, and the validity of the model was verified by comparing it with the experimental results. The model accurately reproduced the loading and unloading behaviors in the experiments for the submicron HOPG cantilevers or the large nonlinear and reversible deformation with a hysteresis loop. Furthermore, the model reproduced well the characteristics of the bending experiments for the micro-MoTe2 cantilevers, or the intermittent decrease in stiffness during the loading process and deformation restoration during the unloading process. These results demonstrated that the designed semi-discrete layer model can be universally applied to reproduce the bending deformation characteristics of a variety of vdW-layered materials and can be employed to effectively elucidate the underlying deformation mechanisms.
The interaction of detonation waves by multipoint initiation under small-size charge condition
Authors: Zhang Qiu , Jian Haotian , Zheng Guoqiang , Li Honggao , Zhu Peng , Shen Ruiqi
Published: November 2023

In this paper, exploding foil overpressure actuator was used to experimentally study the law of detonation wave collision in small-size charge conditions. In order to quantitatively study the growth, propagation, and duration of the ultrahigh-pressure phenomenon created by the detonation wave collision, photon doppler velocimetry was used to measure the pressure value of the detonation waves. And, further tests were conducted to isolate and measure the duration and pressure trend of this phenomenon by height gradient experiments. Meanwhile, the influence of two-point initiation and four-point initiation on the ultra-pressure value were compared. The results indicated that with the increase of explosive height, the colliding wave would undergo a regular oblique reflection to Mach reflection and finally to attenuation. This paper lays a foundation for the multipoint initiation of insensitive explosive and shaped charge.
On matching a microwave radiation with the plasma of an electron cyclotron resonance discharge
Authors: Golubev S. V. , Gospodchikov E. D. , Smolyakova O. B.
Published: November 2023

This article proposes a scheme for matching microwave radiation with a magnetized plasma of an electron cyclotron resonance (ECR) discharge in an open magnetic trap, using the effect of depolarization—the transformation of the ordinary wave into the extraordinary one upon reflection from the metal walls of a plasma chamber. An analysis of the efficiency of such a transformation is carried out, and it is shown that for grazing (less than 15° with metal surface) angles of incidence; it is possible to achieve an efficiency exceeding 90%.
Heat transport with a twist
Authors: Abraham Ethan , Dinpajooh Mohammadhasan , Climent Clàudia , Nitzan Abraham
Published: November 2023

Despite the desirability of polymers for use in many products due to their flexibility, light weight, and durability, their status as thermal insulators has precluded their use in applications where thermal conductors are required. However, recent results suggest that the thermal conductance of polymers can be enhanced and that their heat transport behaviors may be highly sensitive to nanoscale control. Here we use non-equilibrium molecular dynamics simulations to study the effect of mechanical twist on the steady-state thermal conductance across multi-stranded polyethylene wires. We find that a highly twisted double-helical polyethylene wire can display a thermal conductance up to three times that of its untwisted form, an effect which can be attributed to a structural transition in the strands of the double helix. We also find that in thicker wires composed of many parallel strands, adding just one twist can increase its thermal conductance by over 30%. However, we find that unlike stretching a polymer wire, which causes a monotonic increase in thermal conductance, the effect of twist is highly non-monotonic, and certain amounts of twist can actually decrease the thermal conductance. Finally, we apply the Continuous Chirality Measure (CCM) in an attempt to explore the correlation between heat conductance and chirality. The CCM is found to correlate with twist as expected, but we attribute the observed heat transport behaviors to structural factors other than chirality.
Experimental research on a novel dynamic composite distortion simulator
Authors: Liu Zepeng , Zhang Hongxin , Huang Guoping
Published: November 2023

Large-scale dynamic distortion vortexes are generated in advanced complex inlet systems, which can cause serious dynamic distortion flows and influence the performance of engines. Thus, this paper proposes a novel dynamic distortion simulator design method, which uses a column to produce a large-scale streamwise vortex and a rotating valve to enhance the dynamic characteristics, to simulate the complex distortion flow field. Experimental studies were conducted in this paper. The results show that circumferential total pressure and swirl distortion were generated regardless of the valve position. The range of the distortion region decreased significantly when the valve changed from fully closed to fully opened. When the valve rotated continuously, the dynamic total pressure and swirl distortion were generated behind the simulator. At the section, three diameters away from the simulator, the comprehensive distortion index was 7.69%, and the turbulence intensity was 46.4%. The main frequency of the distortion flow field was the same as the switching frequency of the inner channel in the column.
Mixture modeling to simulate helium boiling: Helium gas bubble trapped in high magnetic field
Authors: Hong Wenzhe , Wu Yongsheng , Hu LiBiao , Miao Pengcheng , Liu Huajun , Liu Fang , Shi Yi
Published: November 2023

Multi-phase flow hydrodynamics is an essential theoretical foundation for modernizing engineering and is important in guiding and developing modernizing engineering. In the realm of superconducting power technology, it is imperative to submerge and cool high-field superconducting magnets and superconducting cables, constructed from superconducting materials, in cryogenic fluids in order to maintain a superconducting state. Even minor thermal disturbances can induce boiling of the cryogenic fluid, leading to a two-phase flow regime. In the case of high-field superconducting magnets, the presence of liquid helium as the cooling medium gives rise to a diamagnetic effect. Consequently, the formation of a bubble resulting from boiling is confined in close proximity to the central aperture of the magnet owing to the influence of the magnetic field force. This confinement adversely affects the heat transmission properties of the magnet. This work presents a comprehensive analysis of the flow state during the boiling process of liquid helium, using the finite element approach and the mixture model. The heat transfer in a two-phase flow is analyzed by treating the system as a single pseudo-fluid. The model is consistent with empirical formulations of liquid helium boiling in large vessels and is also suitable for modeling the effect of heating surface orientation on the critical heat flux. Consequently, the analysis of the retention of helium bubbles generated by boiling in a high-field magnet has been further examined, using this particular model. The results of numerical hydrodynamic studies show that the width of the helium bubble stagnation zone is larger compared to the results of hydrostatic calculations. This poses a major challenge for superconducting magnets operating at high magnetic fields and high temperatures. The paper further analyses the effect of supercooled liquid helium on helium bubble stagnation, thus providing valuable insight into the construction of superconducting magnets with high magnetic fields.