bluuebunny/crossref_metadata_2025 huggingface dataset:
A Survey of 251 Facial Paralysis Patients to Assess Their Educational Preparedness and Symptom Management after Treatment of Vestibular Schwannoma
Authors: Barkhoudarian Garni , Sivakumar Walavan , Voelker Courtney J. , Gowrinathan Shanthi , Sharma Akanksha , Li Hsin-Fang , Kochhar Amit
Published: December 2024

Objective The aim of this study was to evaluate how patients with vestibular schwannoma (VS) were prepared for facial paralysis (FP).

Study Design This study comprised an online survey of members of the Acoustic Neuroma Association of America who had FP.

Methods A 28-question survey gathering information on the patient experience related to management of FP was created. Associations between treatment setting and presence of FP were analyzed using SAS Enterprise Guide 8.4. Significance was considered at p-values < 0.05 in a univariate and multivariable model.

Results A total of 251 subjects with VS and FP responded. A total of 14% presented with FP, 70% were diagnosed with VS at least 6 months prior to treatment, and 61% were treated at academic centers. A total of 28% felt prepared for life with FP and 42% were confident their medical team understood management. Less than 30% of respondents received educational materials. After developing FP, speech and swallow difficulty and anxiety were common, but few respondents were referred for expert management. Subjects at academic centers were more often referred to specialists in the same location. Those with preoperative FP felt their medical teams better prepared them for it, had fewer complaints of difficulty speaking, and were happier with their recovery.

Conclusion Significant gaps in preparation and management of FP were identified. Preoperative FP led to improved perception of care; however, the delivery was similar to those without it. Studies of surgeons who manage VS are needed to better understand how they prepare patients for the emotional and physical sequelae of FP.
Assessing the potential of hand grip strength as an indicator of spinal muscle size
Authors: Alharthi Salman M S , Fulford Jonathan , Meakin Judith R
Published: December 2024

In order to assess how well hand grip strength can predict spinal muscle size and to determine if scaling improves prediction Biobank data was acquired consisting of hand grip strength, age, height, body mass and abdominal magnetic resonance images for 150 age-matched male and female participants. The cross-sectional area of the multifidus and erector spinae was measured from the images at the L3/L4 level. Correlation strength and prediction errors were quantified for muscle size predicted from hand grip strength, age, height, and body mass. The effect of scaling muscle area by height and height squared was also determined. All variables correlated significantly with spine muscle size. The strongest correlator was hand grip strength (r = 0.61, p < 0.05) with a prediction error of 678 mm2. The strength of the correlations was reduced when muscle areas were scaled. Hand grip strength can predict spine muscle size in male and female participants; however, the confidence intervals on the predicted values are larger than would be expected from measuring muscle size directly using imaging technologies. Scaling by height or height squared does not improve the ability of hand grip strength to predict muscle size.
Outcomes in Neonates Receiving Therapeutic Hypothermia and Extracorporeal Membrane Oxygenation versus Extracorporeal Membrane Oxygenation Alone
Authors: Cicalese Erin , Seltzer Bryn H.S. , Fisher Jason C. , Verma Sourabh
Published: December 2024

Objective This study aimed to examine survival and outcomes in neonates who received therapeutic hypothermia (TH) for neonatal encephalopathy (NE) and extracorporeal membrane oxygenation (ECMO) versus ECMO alone.

Study Design This is a retrospective review of Extracorporeal Life Support Organization (ELSO) Registry data from 2007 to 2017 for neonates undergoing ECMO and TH for NE (TH/ECMO) or ECMO alone. Primary outcomes were ECMO survival and survival to discharge. Secondary outcomes were complications while on ECMO. Statistical analysis was performed using Fisher's exact and Mann–Whitney U tests. Multivariate regression was performed to identify predictors of ECMO survival.

Results Of 3,672 neonates, 215 (6%) received TH/ECMO, while 3,457 (94%) received ECMO alone. There was no significant difference in ECMO survival (92 vs. 92%, p = 0.70) or survival to discharge (87 vs. 85%, p = 0.43) between groups. TH/ECMO group had higher hemorrhagic (29 vs. 20%, p < 0.01), neurologic (24% vs. 12%, p < 0.01), and metabolic (28 vs. 15%, p < 0.01) complications. Multivariate regression identified higher gestational age, absence of inotropes during ECMO, and lack of neurologic, pulmonary, or hemorrhagic complications as independent predictors of ECMO survival.

Conclusion Neonates undergoing ECMO and TH for NE had survival rates comparable to those receiving ECMO alone. These findings suggest that ECMO can be considered for neonates with NE undergoing TH who meet the criteria for ECMO.

Key Points
Visible-Light-Induced Acridinium-Catalyzed Acylation of Isoquinolines with Aldehydes via HAT
Authors: Singh Praveen P. , Singh Satya Prakash , Mishra Mangla , Tivari Shraddha , Singh Pravin K. , Srivastava Vishal
Published: December 2024

A novel synthetic method utilizes visible light to promote acridinium-catalyzed acylation of substituted isoquinoline via aldehydes in an air atmosphere at room temperature is reported. This method involves the formation of C–C bonds to synthesize the desired product with an excellent yield. This organophotoredox-catalyzed, transition-metal-free synthetic process provides the target compounds in an immensely sustainable manner despite tolerating a broad range of functional groups.
Synthesis of Silyl Heterocycles Using Transborylation
Authors: Willcox Dominic R.
Published: December 2024

Silicon has been proposed as a nonclassical bioisostere to carbon in a ‘silicon-switch’ approach, however, the synthesis of complex molecules containing silyl heterocycles is still a significant challenge in preparing ‘silicon-switch’ molecules. Transborylation, the σ-bond metathesis between two boron species, has been utilized for the synthesis of complex molecules, in an orthogonal approach to transition-metal catalysis. Here, the use of transborylation catalysis for the synthesis of structurally diverse silyl heterocycles is highlighted.

1 Introduction

2 Transborylation in Catalysis

3 Silyl Heterocycles

4 Synthesis of Silyl Heterocycles Using Transborylation

5 Conclusions and Outlook
A Free-Radical Decarboxylative Coupling of Cinnamic Acids with Acetonitrile
Authors: Shang Xiao-Jie , Liu Zhong-Quan , Chu Run , Luo Rui , Zhang Yanjiang
Published: December 2024

A copper-catalyzed decarboxylative coupling of cinnamic acids with acetonitrile was developed. By using the free-radical hydrogen-atom-transfer strategy to activate the C–H bond in acetonitrile, a series of nitrile compounds were successfully synthesized. This method uses the common solvent acetonitrile as a source of a nitrile group for introduction into organic molecules, avoiding the use of highly toxic nitriles in conventional nitrile compound syntheses.
Synthesis, Characterization, and In Vitro and In Silico Biological Evaluation of Novel Polyphenols Bearing a Quinazolin-4(3H)-one Ring as Promising Anti-Prostate-Cancer Agents
Authors: Şenol Halil , Tokalı Feyzi Sinan , Çağman Zeynep , Çakır Furkan
Published: December 2024

In this study, 12 novel polyphenols containing the quinazolin-4(3H)-one ring were synthesized and characterized using 1H/13C NMR and HRMS analyses, yielding the target compounds in excellent yields (88–96%). Biological evaluation revealed significant cytotoxic activity against PC3 prostate cancer and 3T3 fibroblast cell lines, with compounds 2,2′-(propane-1,3-diyl)bis-3-(2,4-dihydroxybenzylideneamino)quinazolin-4(3H)-one (5) and 2,2′-(propane-1,3-diyl)bis-3-(2,3,4-trihydroxybenzylideneamino)quinazolin-4(3H)-one (6) demonstrating the highest anticancer potential. Compound 6 exhibited the highest selectivity (IC50 = 5.72 µM, SI = 68), outperforming the reference drug, doxorubicin. In silico studies, including molecular docking and dynamics simulations, showed strong binding affinities for mTOR, P110α, and PARP1, particularly for compound 6. Key interactions, such as hydrogen bonds and π-π stacking, contributed to the stability of the 6–mTOR complex. These results highlight compounds 5 and 6 as promising candidates for prostate cancer therapy, with compound 6 showing superior selectivity and interaction profiles, providing the groundwork for further preclinical development.
Enzymatic Peroxidation in the Chemoenzymatic Synthesis of 13-Oxoverruculogen
Authors: Ting Chi P. , Singh Brandon
Published: December 2024

Verruculogens are fumitremorgin alkaloids that contain an eight-membered endoperoxide ring. Due to their unusual structure and bioactivity, there has been much interest in these natural products since their discovery over forty years ago. Similarly, interest in their biosynthesis resulted in the discovery of verruculogen synthase (FtmOx1) that catalyzes endoperoxide formation in these natural products. Herein, we describe our work in this area through the chemoenzymatic synthesis of 13-oxoverruculogen by endoperoxidation of a substrate analogue using FtmOx1.

1 Introduction

2 Pentacyclic Ring Formation

3 Promiscuous Enzymatic Peroxidation

4 Conclusion
C–H Functionalization of Quinoxalines
Authors: Laru Sudip , Ghosh Sumit , Hajra Alakananda
Published: December 2024

As a powerful tool in modern organic synthesis, C–H functionalization offers an elegant shortcut to molecular complexity, enabling direct bond transformations without any pre-functionalization. In this connection, the C–H functionalization of quinoxalines offers a direct and efficient approach to modify the quinoxaline scaffold, a key structural motif in biologically active compounds and materials. This personal account describes the methodologies developed by our group for the C–H activation and functionalization of quinoxaline compounds.

1 Introduction

2 Difluoroalkylamidation

3 ortho C–H Alkylation

4 ortho C–H Amination

5 Conclusion
Impact of Systemic Lupus Erythematosus on Conception: Insights into Infertility, Fertility Preservation, Assisted Reproductive Technology, and Pregnancy Outcomes
Authors: Moyer Amanda , Edens Cuoghi
Published: December 2024

Many individuals with systemic lupus erythematosus (SLE) face significant challenges manifesting their family planning goals due to numerous factors, including disease-related complications, treatment-induced effects, immunological factors, self-imposed limitations, and the socioeconomic impacts of having a chronic disease. Instances of unexplained infertility are also prevalent. Encouragingly, advancements in treatment modalities, risk factor management, specialized training within the medical community, and enhanced patient/provider education have contributed to an increase in successful pregnancies among SLE patients, fostering a safer, more promising reproductive landscape. However, despite advances, individuals with SLE continue to struggle with the complexities of family building. This review explores infertility and pregnancy outcomes in SLE, fertility preservation, the role of assisted reproductive technology, and considerations for tailoring these approaches to SLE patients.
Management of Febrile Infants Under 3 Months of Age with SARS-CoV-2 Infection in the Emergency Department
Authors: Diego Patricia , Seguí Aina , Trenchs Victoria , Luaces Carles , Hernández-Bou Susanna
Published: December 2024

Objective Febrile infants with a proven viral infection are at lower risk for a potentially serious bacterial infection (SBI). Our objective is to describe the management of young febrile infants with COVID-19 in the emergency department.

Methods Febrile infants <3 months with a positive PCR (polymerase chain reaction) test for SARS-CoV-2 between March 2020 and October 2022 were included in a cross-sectional study. The indication for complementary tests, hospital admission and antibiotic therapy was analyzed. We performed a global analysis and by age subgroups (<29 d and ≥29 d).

Results A total of 172 patients were included in the study, out of which 32 (18.6%) were <29 days old. Bacterial cultures were performed on 160 patients (93%), with urine cultures being the most frequently requested (151 patients; 87.8%). Overall, 39 infants (22.7%) were hospitalized, and 17 infants (9.9%) received antibiotics. In the subgroup analysis, patients <29 days had performed more frequently urine culture (100 vs. 85%; p = 0.015), blood culture (96.9 vs. 43.6%; p < 0.001), and cerebrospinal fluid culture (18.8 vs. 1.4%; p < 0.001). They also had a higher admission rate (68.8 vs. 12.1%; p < 0.001) and antibiotic prescription (21.9 vs. 7.1%; p = 0.02). SBI was identified in 10 patients (9 with urinary infections and 1 with bacteremia), while no invasive bacterial infection (IBI) was diagnosed in patients aged ≥29 days.

Conclusions The identification of SARS-CoV-2 led to less aggressive management in a significant number of cases compared with usual practice. The low prevalence of IBI would support its inclusion in the management algorithms for febrile infants, especially in patients aged ≥29 days. The nonnegligible prevalence of urinary infection would make it necessary to maintain its screening.
Predicting Renal Cell Carcinoma Subtypes and Fuhrman Grading Using Multiphasic CT-Based Texture Analysis and Machine Learning Techniques
Authors: Gupta Amit , Garg Sanil , Yadav Neel , Dhanakshirur Rohan Raju , Jain Kshitiz , Nayyar Rishi , Kaushal Seema , Das Chandan J.
Published: December 2024

Objectives The aim of this study is to evaluate computed tomography texture analysis (CTTA) on multiphase CT scans for distinguishing clear cell renal cell carcinoma (ccRCC) from non-ccRCC and predicting Fuhrman's grade in ccRCC using open-source Python libraries.

Methods Conducted retrospectively, the study included 144 patients with RCCs (108 ccRCCs and 36 non-ccRCCs) who underwent preoperative multiphasic CT. Ninety ccRCCs were categorized into 71 low-grade and 19 high-grade ccRCCs. Tumor was marked on the largest axial tumor slice using “LabelMe” across different CT phases. First- and second-order texture features were computed using Python's scipy, numpy, and opencv libraries. Multivariable logistic regression analysis and machine learning (ML) models were used to evaluate CTTA parameters from different CT phases for RCC classification. The best ML model for distinguishing ccRCC and non-ccRCC was externally validated using data from the 2019 Kidney and Kidney Tumor Segmentation Challenge.

Results Entropy in the corticomedullary (CM) phase was the best individual parameter for distinguishing ccRCC from non-ccRCC with (F1 score: 0.83). The support vector machine (SVM) based ML model, incorporating CM phase features, performed the best, with an F1 score of 0.87. External validation for the same model yielded an accuracy of 0.82 and an F1 score of 0.81. ML models and individual texture parameters showed less accuracy for classifying low- versus high-grade ccRCCs, with a maximum F1 score of 0.76 for the CM phase SVM model. Other CT phases yielded inferior results for both classification tasks.

Conclusion CTTA employing open-source Python tools is a viable tool for differentiating ccRCCs from non-ccRCCs and predicting ccRCC grade.
A Prospective Comparison of MRI-Guided Targeted Biopsy with 12-Core Transrectal Ultrasound-Guided Systematic Biopsy in the Diagnosis of Clinically Significant Prostate Cancer: An Indian Experience
Authors: Netaji Arjunlokesh , Kubihal Vijay , Sharma Raju , Seth Amlesh , Kaushal Seema , Das Chandan J.
Published: December 2024

Objective The aim of this study was to compare the sensitivity and prostate cancer detection rate of magnetic resonance (MR) in-bore biopsy with transrectal ultrasound (TRUS) guided systematic biopsy. We also compared the cancer detection rate of the combined MR in-bore and TRUS-guided systematic biopsy with the TRUS-guided biopsy only approach.

Methods In this prospective study, 61 consecutive patients with prostate-specific antigen (PSA) ≥ 3 ng/mL and Prostate Imaging Reporting and Data System (PI-RADS) score ≥4 were recruited between July 2017 and January 2020. One patient with prior prostate surgery was excluded. Among the remaining 60 patients, 30 underwent MR in-bore biopsy followed by systematic biopsy (study arm A) and 30 underwent systematic biopsy only (study arm B).

Results The mean PSA range of study population (n = 60 patients) was 4.2 to 72.7 ng/mL. Twenty-seven patients had a PI-RADS score of 4, and 33 patients had a PI-RADS score of 5. Among 60 patients, 30 had prostate carcinoma on biopsy, of which 18 were clinically significant prostate cancers (csPCa). In study arm A, TRUS-guided systematic biopsy had a lower sensitivity (0.9) for detection of csPCa compared with MR in-bore biopsy (1.0) with overdetection of insignificant cancers (sensitivity: 0.89 vs. 0.56). TRUS-guided biopsy yielded 112 positive cores out of 360, whereas MR in-bore biopsy yielded 15 positive cores out of 30 (31.1 vs. 50%; p = 0.03). On comparison of study arms A and B, the diagnostic yield for detection of both prostate cancer and csPCa were high in study arm A (60 vs. 40%, and 33.3 vs. 26.7%, respectively)

Conclusion MRI in-bore targeted biopsy had a greater sensitivity to detect csPCa with fewer number of biopsy cores and lower sensitivity to detect insignificant cancers compared with systematic biopsy. Systematic biopsies were associated with overdetection of clinically insignificant cancers.
Gynecomastia: The 4Dx technique
Authors: Goel Aakanksha , Punia Sudhanshu , Gupta Amit
Published: December 2024

In surgery for gynecomastia, it is not sufficient to just remove the gland or do a liposuction that addresses the front of the chest only as it is not aesthetically pleasing for the patient and the surgeon alike. Most patients expect to achieve a sculpted look, which includes not only the breast area but also the surrounding areas such as the sides, the axillae, and the infraclavicular region. To tackle these areas and achieve a well-sculpted and aesthetic look, we describe the 4Dx (4 Directions) technique of liposuction for gynecomastia. It also makes the procedure more objective for plastic surgeons while allowing for individualization of the procedure.
Ultrasound-Guided Partial Release of Transverse Carpal Ligament in Severe Carpal Tunnel Syndrome Using a Curved Needle
Authors: Kumar Nishith , Singh Upinderjeet , Singh Dharmendra Kumar , Saifi Alfa Shamim
Published: December 2024

Ultrasound (US) is an excellent tool for diagnosis and management of carpal tunnel syndrome (CTS). Severe, recalcitrant CTS is an indication for complete release of the transverse carpal ligament (TCL). However, complete TCL release may be associated with postprocedural pillar pain. US-guided partial division of the TCL using a curved needle can be a safe and effective technique for reducing the tensile compression onto the median nerve while mitigating the occurrence of pillar pain.
A Radiologist's Perspective of Medical Annotations for AI Programs: The Entire Journey from Its Planning to Execution, Challenges Faced
Authors: Rao Anuradha
Published: December 2024

Artificial intelligence (AI) in radiology and medical science is finding increasing applications with annotations being an integral part of AI development. While annotation may be perceived as passive work of labeling a certain anatomy, the radiologist plays a more important role in this task apart from marking the structures needed. Apart from annotation, more important aspect of their role is planning the anatomies/pathologies needed, type of annotations to be done, choice of the annotation tool, training the annotators, planning the duration of annotation, etc. A close interaction with the technical team is a key factor in the success of the annotations. The quality check of both the internally and externally annotated data, creating a team of good annotators, training them, and periodically reviewing the quality of data become an integral part of their work. Documentation related to the annotation work is another important area where the clinician plays an integral role to comply with the Food and Drug Administration requirements, focused on a clinically explainable and validated AI algorithms. Thus, the clinician becomes an integral part in the ideation, design, implementation/execution of annotations, and its quality control. This article summarizes the experiences gained during planning and executing the annotations for multiple annotation projects involving various imaging modalities with different pathologies.
Role of a rare-earth sublattice in the high-frequency properties of ferrite–garnets
Authors: Krivoruchko V. N.
Published: December 2024

The high-frequency and thermodynamic properties of rare-earth ferrite–garnets (REFG) are investigated in a broad range of wave vectors and temperatures, including the temperatures at which the sublattice of the rare-earth (RE) spins is in the paramagnetic (PM) state. It is shown that the role of the magnetization fluctuations of the RE sublattices is strongly attenuated in the magnetically ordered state of the REFG. At the same time, the principal contribution to the temperature dependence of the spin wave spectrum is given by linear corrections in the temperature from the PM spin vibrations, and the fluctuating attenuation of the spin waves considerably exceeds the total attenuation of the magnons in yttrium–iron garnet (YIG).
Diagnostic development and needs for laser driven MeV x-ray radiography
Authors: Rusby D. R. , Williams G. J. , Kerr S. M. , Aghedo A. , Alessi D. , Anderson S. , Hill M. , Rodger I. , Rubery M. , Selwood M. P. , Treffert F. , Mackinnon A. J.
Published: December 2024

Laser-driven MeV x-ray radiography of dynamic, dense objects demands a small, high flux source of energetic x-rays to generate an image with sufficient quality. Understanding the multi-MeV x-ray spectrum underscores the ability to extrapolate from the current laser sources to new future lasers that might deploy this radiography modality. Here, we present a small study of the existing x-ray diagnostics and techniques. We also present work from National Ignition Facility-Advanced Radiographic Capability, where we deploy three diagnostics to measure the x-ray spectrum up to 30 MeV. Finally, we also discuss the needs and developments of two new diagnostics: a single crystal scintillator spectrometer and a fast decay activation.
The hardware, tracer, and signal processing methods of magnetic particle imaging: A review
Authors: Davida Angga , Basari Basari
Published: December 2024

Magnetic Particle Imaging (MPI) has advanced rapidly from its first conceptualization, showing promise as a viable clinical imaging modality. Despite its promise, several aspects of MPI, such as hardware design, tracer design, and image reconstruction method, still require further technical development to overcome their current limitations. This review provides the basic concept for MPI, introduces the limitations of upscaling MPI, and discusses several aspects of MPI development. Among them are the advantages and disadvantages of using different field-free regions (FFR), bore configurations, elaborating on the challenges in upscaling, describing the optimal characteristics of MPI tracers, discussing tracer synthesis methods and biocompatible coatings, tracer toxicity reports, and finally a basic explanation regarding the various image reconstruction methods. Additionally, this review provides several examples of state-of-the-art MPI devices and prototypes with varying bore designs, FFR designs, magnetic field sources, and intended use cases to demonstrate both the wide range of applications and the progress of recent research in MPI. With all this information compiled, this review serves to shed insight for researchers in the field of MPI or those intending to enter the world of MPI. It is hoped that this review will encourage the future development of MPI, accelerating its viability for clinical implementation.
Investigation on a high power compact K-band transit-time oscillator with bilateral distributed extraction structure
Authors: Zhang Wei , Yao Hongtao , Ju Jinchuan , Wang Tengfang , Zhou Yunxiao , Li Ying , Zhang Jun
Published: December 2024

With the continuous pursuit of high power and high frequency in the area of high-power microwave (HPM) sources, the overmoded ratio of HPM devices is usually designed to be larger in K and Ka-band to alleviate the issue of high electric field in the extraction structure. Nevertheless, this approach inevitably results in a large radial size, which in turn requires larger magnetic field coils and higher energy consumption. To address this challenge, we present a method of bilateral distributed energy extraction in a compact GW level K band transit time oscillator. Particle-in-cell simulations show that with a central radius of 3 cm and the output microwave power of 2.0 GW, the maximum axial electric field is controlled at 1.18 MV/cm at 18.6 GHz. By reducing the electron beam voltage from 500 kV to 475 kV, an output power exceeding 1.79 GW can be achieved and the field will decrease to 0.98 MV/cm.
Neural network based fast prediction of double tearing modes in advanced tokamak plasmas
Authors: Xu Jian , Luan Qibin , Li Hui , Chen Yumeng , Wang Zhengxiong
Published: December 2024

An advanced tokamak operation featuring reversed magnetic shear configuration can trigger double tearing modes, a deleterious resistive magnetohydrodynamic (MHD) instability that plays a crucial role in causing major disruptions. Generally, the properties of the double tearing mode can be investigated through solving MHD equations. However, solving MHD equations is widely recognized as a challenging task due to the complex physical model, massive CPU requirements, and lengthy computation time. A surrogate model based on MHD equations can quickly provide physics-based instability information, such as the mode growth rate, serving as references for future control needs. In this work, a reliable surrogate prediction model, LTM-NN, is established using a neural network (NN) based on a numerical database. This work employs a linear tearing mode (LTM) code with a large aspect ratio tokamak configuration to construct a supervised learning dataset of equilibria and growth rates. It is found that the trained LTM-NN predicts growth rates with a high accuracy up to 97%, and the classification accuracy for the stability of the double tearing mode reaches 100%. Furthermore, LTM-NN is applied to systematically investigate the dependence of the growth rate on the inter-resonance distance, the magnetic shear, and the magnetic Reynolds number. The results are consistent with existing theories. Thus, high accuracy, fast computing speed, and correct parameter dependencies demonstrate that LTM-NN is capable of serving as a rapid predictor of double tearing modes to provide instability information for the integrated model or the disruption warning model in the future.
Crater-shaped enrichment of VSi color centers in 4H-SiC using single-pulse near-infrared femtosecond laser processing
Authors: Yan Mengzhi , Zhao Junlei , Song Ying , Dong Bing , Duan Yifei , Wang Jianshi , Sun Qingqing , Xu Zongwei
Published: December 2024

Currently, silicon vacancy (VSi) color centers in SiC are of significant interest due to their potential applications in quantum sensing and quantum communication. Meanwhile, femtosecond lasers, as a non-thermal processing technique, offer considerable advantages in machining hard and brittle materials, such as SiC. Femtosecond laser processing effectively increases the yield of VSi color centers in bulk materials and forms crater-shaped enriched regions on the surface. However, a notable gap exists in simulation methods to explain the mechanisms behind laser-assisted VSi color center generation. In this work, we develop a three-dimensional molecular dynamics (3D-MD) model using an integral hemi-ellipsoidal shell mathematical framework to simulate the interaction of Gaussian laser beams with bulk materials. Additionally, we calculate the transmittance, absorption coefficient, refractive index, and reflectivity of 4H-SiC. Subsequently, the absorption ratio of a 1030 nm laser in 350 μm thick 4H-SiC material is determined to simulate the energy loss during actual processing. Finally, the study analyzes the movement trajectories of VSi color centers and elucidates the source of VSi on the surface. This analysis explains the enrichment of color centers in the crater-shaped regions formed after laser deposition. Our work presents an effective 3D-MD modeling approach to study the processing mechanisms of laser interaction with semiconductor materials, offering insights into efficient VSi color center creation processes.
Unveiling frequency dependence of electrical treeing degradation in epoxy resin under bipolar square wave voltage
Authors: Zhang Chuang , Xiang Jiao , Ruan Yang , Cui Huize , Wang Shihang , Li Jianying , Li Shengtao
Published: December 2024

The epoxy insulation used in high frequency transformers encountered breakdown easily due to bipolar square wave voltage with steep rising/falling edge and high frequency. An insight into the frequency dependence of electrical tree development in epoxy resin under bipolar square wave voltage was elucidated in this paper. It was found that luminescence existed in all treeing channels, where the intensity of luminescence at the electrical tree tip under a high frequency (>4 kHz) was stronger than that at a low frequency (<4 kHz), indicating an electric field delivery from the needle tip to the channel tip at high frequency. Correspondingly, the fluorescent material deposited on the wall of the tree channel evolved from discontinuous at a low frequency to continuous at a high frequency with aggravated degradation. In addition, the frequency dependence of electrical tree breakdown related to field delivery was revealed. By combining the field delivery along treeing channels and the frequency dependence of the mechanical properties of epoxy resin, the growing model of an electrical tree under bipolar square wave voltage was illustrated elaborately. It was proposed that the dominant factors that drove electrical tree propagation were electric field force at a low frequency and partial discharge at a high frequency, respectively. This work can boost the advancement of polymers, electrical equipment, and power electronics at a high frequency.
Experimental study of the detachment behavior of bubbles of different sizes from a hydrophobic surface immersed in a liquid pool using direct current electrowetting actuation
Authors: Kim Taeyung , Lee Yoon Jae , Kim Bosung , Hong Jiwoo
Published: December 2024

The unexpected presence of microbubbles in microfluidic systems typically results in performance degradation owing to their ability to obstruct fluidic pathways, causing pressure fluctuations or shear force variations. To develop or enhance undesired bubble-removal strategies, a solid understanding of the fundamental physics governing the bubble-removal processes is essential. In this context, the present study aims to thoroughly investigate the detachment dynamics of different-sized bubbles, ranging in volume from 3 to 75 μL, from a hydrophobic surface fully submerged in a liquid pool while being subjected to direct current electrowetting (DC EW) actuation. From systematic experimental data on the temporal variations in the base radius of retracting bubbles of different volumes subjected to varying DC EW actuations, empirical relationships between detachment process characteristics (e.g., threshold voltage for bubble detachment and detaching time) and physical factors (e.g., bubble volume and applied voltage) can be determined. These relationships are compared with predictions derived from scaling analysis. The findings will provide valuable insight into the elimination of unwanted bubbles in microfluidic systems for biomedical applications and the rapid removal of bubbles to improve heat transfer rates in pool boiling for thermal management applications, including heat exchangers and cooling systems.
Influence of layer thickness on time domain Brillouin scattering oscillation amplitude in multilayer films
Authors: Zhang Enrui , Zhao Hongyuan , Geng Zhiming , Yan Xuejun , Xu Xiaodong , Dai Jiayu
Published: December 2024

This paper investigates the impact of a sample structure on the amplitude of time-domain Brillouin scattering (TDBS) oscillations using silicon wafers with different oxide layer thicknesses as an example. According to the calculation results based on transfer matrix theory and Green’s function, along with experimental results, we discovered that the amplitude of TDBS exhibits dual peaks corresponding to the thickness of the silicon dioxide layer, highlighting the TDBS’s acute sensitivity to an internal sample structure. Furthermore, our computational results indicate that both the roughness of the sample and the non-monochromatic nature of the probe light affect the time-domain Brillouin scattering signal, underscoring the significant role of interference effects in TDBS detection. The outcomes of this study suggest that by precisely designing the thickness of the transducer layer, the time-domain Brillouin scattering signal can be enhanced, and it may be possible to determine the roughness of the sample using the amplitude of the time-domain Brillouin oscillation. This is beneficial for improving the detection accuracy of time-domain Brillouin scattering and for extracting a broader range of physical information from TDBS oscillations.
Density functional theory for fractional charge: Locality, size consistency, and exchange-correlation
Authors: Kong Jing
Published: December 2024

We show that the exact universal density functional of integer electronic charge leads to an extension to fractional charge in an asymptotic sense when it is applied to a system made of asymptotically separated densities. The extended functional is asymptotically local and is said to be i-local. The concept of i-locality is also applicable to nuclear external potentials, and a natural association exists between the localities of a density and a set of nuclei. Applying the functional to a system with nuclei distributed in two asymptotically separated locales requires an explicit search of the electronic charge at each locale with the constraint of the global charge. The determined number of electrons at each locale can be fractional. The molecular size consistency principle is realized as the result of the search. It is physically sensible to extend the molecule concept to include a fractional number of electrons (called fractional molecule henceforth) as a localized observable. The physical validity of fractional molecules is equivalent to the asymptotic separability of molecules, a basic assumption in molecular research. A one-to-one mapping between a fractional molecule’s density and external potential is shown to exist with a nondegenerate condition. The global one-to-one mapping required by the Hohenberg–Kohn first theorem is realized through the aforementioned global search for molecular charges. Furthermore, the well-known piecewise linearity of the universal functional with respect to the number of electrons is necessary for an approximate i-local universal functional to be broadly accurate for any integer number of electrons. The Kohn–Sham (KS) noninteracting kinetic energy functional for a fractional molecule is well-defined and has the same form as that for a system of an integer number of electrons. It is shown to be i-local. A nondegenerate, noninteracting ensemble v-representable fractional density is simultaneously noninteracting wavefunction representable. A constrained search over those representing wavefunctions yields the definition of an exchange–correlation functional pertaining to fractional occupancies of KS orbitals. The functional is shown to be an upper bound to the formal KS exchange–correlation energy of a fractional molecule and includes a strong correlation. It yields the correct result for a well-designed example of effective fractional occupancies in the literature.
Coupled methyl internal rotations with intermediate and low torsional barriers in 2,5-dimethylanisole investigated by microwave spectroscopy
Authors: Sun Haoyue , Ferres Lynn , Kleiner Isabelle , Nguyen Ha Vinh Lam
Published: December 2024

We recorded and analyzed the microwave spectra of 2,5-dimethylanisole using a pulsed molecular jet Fourier transform microwave spectrometer and the newly developed Passage And Resonant-Impulse Synergy spectrometer across a frequency range of 2–26.5 GHz with support from quantum chemical calculations. Only one conformer was predicted and observed, where the methoxy group and its adjacent methyl group adopt anti-positions. The two methyl groups, located at the ortho- and meta-positions of the anisole ring, exhibit internal rotation, resulting in quintet splitting of all rotational transitions. The low torsional barrier of the m-methyl group, amounting to 65.723 611(84) cm−1, combined with the intermediate barrier of 451.664(19) cm−1 for the o-methyl group, presented challenges in the spectral analysis. Using the XIAM and BELGI-Cs-2Tops programs, we successfully fitted 460 torsional intrastate rotational transitions, allowing for precise determination of molecular parameters and internal rotation characteristics. The torsional barriers are compared to those in the related isomers 2,3-, 2,4-, and 3,4-dimethylanisole as well as other o- and m-substituted toluene derivatives.
Hydrodynamic performance of a surface-piercing hydrofoil with differing oblique angle: A numerical study
Authors: Huang Jianlin , Wang Jingzhu , Lu Xingyu , Chen Yonggang , Li Yantao , Du Tezhuan , Wang Yiwei
Published: December 2024

Oblique surface-piercing hydrofoils are used widely to impart lift to high-speed surface vehicles, and their lift and drag, and hence working efficiency, are affected by their oblique angle and velocity. Reported here is a numerical study of the ventilation and hydrodynamic performance of a surface-piercing hydrofoil with an oblique angle, using the two-phase interFoam solver in OpenFOAM to simulate the hydrofoil processes. The results show that two main regimes occur when the surface-piercing hydrofoil moves in a stable manner, i.e., fully wetted and fully ventilated (the latter comprising tip-vortex-induced ventilation and perturbation-induced ventilation), which are affected by the oblique angle. At low velocity, increasing the oblique angle does not change the ventilation regime but does improve the lift-to-drag ratio of the hydrofoil. At high velocity, as the oblique angle increases, the hydrofoil changes from tip-vortex-induced ventilation to fully wetted, and the lift-to-drag ratio is also increased. In particular, when the oblique angle reaches 30°, perturbation-induced ventilation occurs and the hydrofoil stalls. A phase diagram of the ventilation regime at different values of the Froude number and oblique angle is presented. Given that surface-piercing hydrofoils impart lift to high-speed surface vehicles, an oblique angle of 25° is recommended as being suitable for hydrofoils within the parameters discussed in the paper. These findings support the engineering applications of surface-piercing hydrofoils.
Majorana fermion induced power-law scaling in the violations of the Wiedemann–Franz law
Authors: Mishra Sachiraj , Das Ritesh , Benjamin Colin
Published: December 2024

Violation of the Wiedemann–Franz law in a 2D topological insulator due to Majorana bound states is studied via the Lorenz ratio in the single-particle picture. We study the scaling of the Lorenz ratio in the presence and absence of Majorana bound states with inelastic scattering modeled using a Buttiker voltage–temperature probe. We compare our results with those seen in a quantum dot junction in the Luttinger liquid picture operating in the topological Kondo regime. We explore the scaling of the Lorentz ratio in our setup when either phase and momentum relaxation or phase relaxation is present. This scaling differs from that predicted by the Luttinger liquid picture for both uncoupled and coupled Majorana cases.
Active modulation of polarization-independent plasmon-induced transparency metasurfaces using phase change materials
Authors: Guo Wenpeng , Wang Yu , Liu Chenxiang , Tan Peng , Wang Guanchao , Li Li , Tian Hao
Published: December 2024

Plasmon-induced transparency (PIT) metasurfaces have emerged as a promising platform for applications in ultrasensitive detection and slow-light devices. The active control of PIT metasurfaces is particularly crucial for advancing these applications. In this study, we integrate the phase change material Ge2Sb2Te5 (GST) into the structural design of a polarization-independent metasurface, enabling the experimental realization of ultra-large depth modulation of PIT peaks. This was achieved through direct thermal activation of the sample and laser-induced multilevel nonvolatile modulation, with a modulation range extending from 0% to 35.2%. The underlying mechanism for this significant modulation depth is attributed to the suppression of magnetic resonance by the GST phase transition, which is elucidated through analyses of multipolar scattering power, electric field distribution, and magnetic field distribution. The proposed terahertz metasurface presents a pathway for the development of optical switches and slow-light devices, with potential applications in advanced photonic systems.
The impact of multiple startups and startup parameters on the mass flow rate characteristics of powder fuel
Authors: Yang Jiangang , Hu Chunbo , Zhang Xiangwen , Gao Wei , Cao Yijun , Luo Fuya , Ma Kai
Published: December 2024

To clarify the impact of multiple startups and startup parameters on the mass flow rate characteristics of powder fuel in a powder ramjet engine, this paper employs experimental and modeling methods to conduct an in-depth analysis of the fluidization and transportation characteristics of boron-based powder fuel under different startup conditions. The results demonstrate that the intake process of the first startup compresses the volume of the powder fuel, and during the working phase, the powder fuel's stacking profile evolves from a flat surface to a conical surface. These factors result in a longer mass flow rate response delay in the first startup (Δt = 9.4 s) compared to the second startup (Δt = 2.8 s). Presetting the stacking profile of the powder fuel as a cone and increasing the initial pressure of the storage tank to 0.17 MPa can significantly shorten the powder mass flow rate response time in the first startup, to Δt = 3 s and Δt = 0.54 s, respectively. The obstruction of the powder fuel at the intake position causes pressure fluctuations, with frequencies ranging between 2 and 4 Hz. The reaction force of the conical inner wall surface has a greater volume compression effect on the powder fuel than the intake process alone. Furthermore, the powder mass flow rate model based on the powder compression equation can accurately predict the powder mass flow rate during the stable supply phase, with a prediction accuracy of 3.1%.
Comparative analysis of the effect of crosswind speed and direction on snow accumulation of high-speed train bogies region
Authors: Ma Yuzhe , Zhang Jiye , Shi Jiawei , Zhang Lan
Published: December 2024

High-speed trains operating in snowy conditions during winter encounter complex variations in wind speed and direction, which can significantly affect snow accumulation on bogies and impact train safety. This paper employs sliding mesh method, discrete phase model, and MATLAB to simulate snow accumulation by generating a random point lattice on the ground. Chinese hat gust model and uniformly rotating crosswind model are designed to investigate the influence of crosswind speed and direction on snow accumulation on high-speed train bogies. The results indicate that as crosswind speed increases from 5 to 15 m/s, the snow mass on the bogies changes as follows: bogie 1 experiences slight fluctuations, bogies 2–4 gradually decrease, bogie 5 increases, and bogie 6 initially increases and then decreases. In comparison with the steady wind, directionally rotating crosswinds result in a 29.8%, 12.8%, 10.5%, 7.5%, 26.6%, and 26.7% increase in the number of snow particle impacts per bogie, respectively. The mass of snow accumulation per bogie is increased by factors of 1.56, 1.17, 0.32, 1.15, 0.48, and 0.67, respectively. The Chinese hat gust model does not exhibit unique effects compared to steady wind models. Crosswinds cause uneven distribution of snow particles on bogies, with snow accumulation being more pronounced on leeward side, particularly on the frame and cavity. Uniformly rotating crosswinds change friction wind speed on the surfaces beneath the train and in the bogie region, leading to a significant increase in both the number of snow particle impacts and the mass of snow accumulation on the bogies.
Diffusion-driven deposition model suggests stiffer gels deposit more efficiently in microchannel flows
Authors: Smith Barrett T. , Hashmi Sara M.
Published: December 2024

The behavior of cross-linking polymer solutions as they transition from liquid-like to solid-like material in flow determines success or failure in several applications. Dilute polymer solutions flow easily, while concentrated polymers or crosslinked polymer gels can clog pores, nozzles, or channels. We have recently described a third regime of flow dynamics in polymers that occurs when cross-linking happens during flow: persistent intermittency. When a dilute alginate solution meets calcium at a Y-shaped microfluidic junction, a persistent and regular pattern of gel deposition and ablation emerges when driven at a constant volumetric flow rate. Chemical concentrations and flow rate control both the gel deposition and critical shear stress required to ablate the adhered gel. In this work, we provide an analytical framework to quantitatively describe the intermittent behavior as resulting from diffusively driven deposition in a high Peclet number flow. Fitting the experimental data shows that higher component concentrations lead to more efficient deposition and more swollen gels. Increasing the flow rate increases the deposition rate, but the resulting gels are much less swollen. Ablation occurs when applied shear stresses overcome either the adhesive energy of the gel or its yield stress. The shear stress required at ablation decreases with increased component concentrations. By correlating the results of the analytical analysis with bulk rheology measurements, we find that deposition efficiency increases with the stiffness of the gel formed in flow. Softer gels withstand higher shear stresses before ablation. Both deposition efficiency and gel stiffness increase in flow conditions nearing complete clogging.