bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Elective Revision after Breast Reconstruction on Patient-Reported Outcomes
Authors: Zong Amanda M. , Leibl Kayla E. , Weichman Katie E.
Published: May 2024

Background There has been increasing emphasis on patient-reported satisfaction as a measure of surgical outcomes. While previous research has investigated factors influencing patient satisfaction following breast reconstruction, there are few studies on how patient satisfaction is impacted by revision procedures. The purpose of this study was to investigate whether elective revisions following breast reconstruction are significantly associated with changes in patient-reported outcomes and quality of life.

Methods A retrospective review was conducted of patients who underwent immediate autologous or alloplastic breast reconstruction at a single institution from 2015 to 2021. Patients were included if they had completed BREAST-Q preoperatively, post–initial reconstruction, and post-revision procedures. Patients were excluded if they received adjuvant radiation or if they had previously undergone breast reconstruction procedures. The primary outcome measures were BREAST-Q domains. Demographic, clinical, and surgical variables were also analyzed.

Results Of the 123 patients included for analysis, 61 underwent autologous breast reconstruction and 62 underwent alloplastic reconstruction. Mean age was 49.31 ± 11.58 years and body mass index (BMI) was 29.55 ± 5.63 kg/m2. Forty-eight patients underwent no revision procedures and 75 patients underwent at least one revision. Between these two groups, there were no differences in age, BMI, complication rates, socioeconomic status, or preoperative BREAST-Q scores. Patients reported significantly higher satisfaction with outcome after their first revision compared with after initial reconstruction alone (p = 0.04). Autologous reconstruction patients who had at least one revision had significantly higher satisfaction with outcome (p = 0.02) and satisfaction with surgeon (p = 0.05) in the 2-year follow-up period compared with patients who had no revisions.

Conclusion Revision procedures following autologous breast reconstruction are associated with higher patient satisfaction with outcome. Further research should explore specific factors influencing patient decision-making regarding whether to undergo revisions.
Biflanged metal stents versus plastic stents for endoscopic ultrasound-guided drainage of walled-off necrosis: a randomized controlled trial
Authors: Koduri Krithi Krishna , Jagtap Nitin , Lakhtakia Sundeep , Jahangeer Basha , Asif Shujaath , Talukdar Rupjyoti , Trikudanathan Guru , Tandan Manu , Kalapala Rakesh , Nabi Zaheer , Gupta Rajesh , Ramchandani Mohan , Singh Jagadish , Memon Sana Fatima , Rao G. Venkat , Reddy D. Nageshwar
Published: May 2024

Background Endoscopic ultrasound (EUS)-guided drainage of walled-off necrosis (WON) using either plastic or metal stents is the mainstay of WON management. Our single-center randomized controlled trial aimed to evaluate the efficacy of biflanged metal stents (BFMSs) and plastic stents for WON drainage.

Methods Patients with symptomatic WON amenable to EUS-guided drainage were randomized to receive either BFMSs or plastic stents. The primary outcome was reintervention-free clinical success at 4 weeks. Secondary outcomes were: overall clinical success (complete resolution of symptoms and significant reduction in size of WON [<50% of original size and <5 cm in largest diameter at 4-week follow-up]); number of reinterventions; adverse events (AEs); hospital stay for first admission; and medium-term outcomes at 6 months (recurrence, disconnected pancreatic duct, chronic pancreatitis, and new-onset diabetes mellitus).

Results 92 patients were randomized: 46 in each arm. The reintervention-free clinical success rate was significantly higher in the BFMS group on intention-to-treat analysis (67.4% vs. 43.5%; P = 0.02). Overall clinical success at 1 month was similar in both groups. There were significantly fewer reinterventions (median 0 [IQR 0–1] vs. 1 [0–2]; P = 0.03) and shorter hospital stays in the BFMS group (7.0 [SD 3.4] vs. 9.1 [5.5] days; P = 0.04). There were no differences in procedure-related AEs, mortality, or medium-term outcomes.

Conclusions BFMSs provide better reintervention-free clinical success at 4 weeks, with shorter hospital stay and without increased risks of AEs, compared with plastic stents for EUS-guided drainage of WON. Medium-term outcomes are however similar for both stent types.
Copper(II) Triflate Catalyzed Rearrangement of Amino 2,3-Epoxides to α-Amino Ketones
Authors: Akkarasamiyo Sunisa , Chitsomkhuan Saranya , Buakaew Supawadee , Samec Joseph S. M. , Chuawong Pitak , Saymaya Jenjira , Kuntiyong Punlop , Pluempanupat Wanchai
Published: May 2024

α-Amino ketones were synthesized by a Meinwald rearrangement of biomass-based amino epoxides using copper(II) triflate as a catalyst. The regioselectivity of the rearrangement can be rationalized in terms of the reaction proceeding via the most stable carbocationic intermediate to give various α-amino α′-aryl ketones in moderate to good yields. This is an attractive method to prepare α-amino ketones using a benign and inexpensive catalyst.
Postoperative Pain Reduction in “Cesarean Mothers” with Hand and Foot Massage
Authors: Joseph Anitha , Frank Reena Wilma , S. Ramyashree
Published: May 2024

Objective Experiencing the miracle of childbirth is a profound and joyous moment for every woman. However, amidst this happiness, it is important to acknowledge the physical pain associated with childbirth. As a result, there is a pressing need to address the imperative of alleviating pain in women undergoing cesarean sections. A significant number of women choose cesarean section as a means to circumvent the challenges associated with the labor process.

Method A quasi-experimental nonequivalent control group pretest and posttest design was adopted in this study. Using the purposive sampling method, 60 mothers who underwent cesarean-section were selected and randomly assigned to the intervention and control groups. Data were collected using the baseline proforma and Numerical Pain Rating Scale. A pretest was carried out for both groups using the Numerical Pain Rating Scale. The intervention group received hand and foot massages for 20 minutes twice daily (morning and evening) for 3 days. After 5 minutes of intervention, both groups underwent a posttest.

Results The mean preintervention pain score on day 1 was 8.10 ± 0.61, and the mean percentage was 81, whereas the posttest mean score was 7.00 ± 0.64 and the mean percentage was 70. There was a decline in the pretest and posttest from day 2 onward. Between the pretest and posttest, pain scores showed a significant difference in the intervention group (F-value (11&319) = 498.32, p = 0.001).

Conclusion Mothers who underwent cesarean section benefited from hand and foot massage.

Clinical Significance This article holds significance in the contemporary landscape, wherein a substantial number of women opt for cesarean sections due to either pregnancy complications or personal choice. The latest research outcomes contribute to mitigating pain through the implementation of nonpharmacological approaches.
Research Strategies for Precise Manipulation of Micro/Nanoparticle Drug Delivery Systems Using Microfluidic Technology: A Review
Authors: Liu Jie , Fu Qinghui , Li Qin , Yang Yani , Zhang Yue , Yang Kaili , Sun Guohao , Luo Jiayu , Lu Weigen , He Jun
Published: May 2024

Microfluidic technology facilitates precise control over fluid mixing and interactions between the components, including self-assembly and precipitation. It offers new options for accurately manufacturing particles and holds significant potential in advancing micro/nanoparticle drug delivery systems (DDSs). Various microchannel/microfluidic chips have been explored to construct micro/nanoparticle DDSs. The precise manipulation of particle size, morphology, structure, stiffness, surface characteristics, and elasticity through microfluidic technology relies on specific microchannel geometrical designs and the application of exogenous energy, adhering to the principles of fluid motion. Consequently, this enables reproducible control over critical quality attributes (CQAs), such as particle size and distribution, encapsulation efficiency, drug loading, in vitro and in vivo drug delivery profiles, Zeta potential, and targeting capabilities, for micro/nanoparticle DDSs. In this review, we categorize microfluidic techniques and explore recent research developments in novel microchannel structures spanning the past 5 years (2018–2023) and their applications in micro/nanoparticle DDSs. Additionally, we elucidate the latest manipulation strategies of microfluidic techniques that impact foundational structures related to the CQAs of micro/nanoparticle DDSs. Furthermore, we offer insights into the industrial applications and challenges microfluidic techniques face in the context of novel micro/nanoparticle DDSs.
Neuroplastic Surgery Principles of Computerized Surgical Planning in Complex Cranioplasty Reconstruction
Authors: Perez Colleen F. , Gordon Chad R.
Published: May 2024

This article explores the evolution and implementation of three-dimensional (3D) models and Computerized Surgical Planning (CSP) for complex cranioplasty reconstruction and the advances in neuroplastic surgery principles for improved surgical outcomes. Over recent years, CSP has revolutionized the field by employing detailed medical imaging to enhance the accuracy and efficacy of 3D models and for the creation of customized cranial implants (CCIs). The study discusses the advancements of solid alloplastic implants to the future of implants with sophisticated and integrated neurotechnology to treat or enhance patient outcomes. CSP can be used to identify and mitigate complications that can occur within cranioplasty reconstruction and to create CCIs to address the postoperative challenge of temporal hollowing. Despite the promising advancements, the article acknowledges the current limitations of CSP, including cost and technological accessibility, and proposes future directions for research and development. The findings suggest that with further improvements in imaging, biomaterials, and manufacturing techniques, CSP in neuroplastic surgery and other specialties will continue to significantly enhance the precision and personalized care of cranioplasty reconstruction.
Breaking the stigma: the joint effort of the government, print media, and citizens toward transgender education equality (2018–2022)
Authors: Rehman Nadia , Huang Xiao , Zhang Li , Mahmood Amir , Zamani Noushin
Published: May 2024

The issue of transgender education and equality has long been neglected in Pakistan, leading to a lack of awareness and acceptance of the transgender community. The present study focuses on the joint effort of the government, print media, and citizens toward breaking the stigma and promoting transgender education and equality. This study employed a mixed-methods approach, combining qualitative content analysis of articles from three prominent Pakistani media outlets with a quantitative public opinion survey to evaluate the extent of media coverage and public attitudes toward transgender education and equality. This coverage helped create awareness and understanding of the transgender community. The government also took significant steps (Transgender Act 2018) by passing policies favoring the transgender community. Furthermore, the study showed that citizens have a positive attitude toward transgender equality, a sign of creating an inclusive society. The study also concluded that joint efforts between the government, print media, and citizens can help people break the stigma and promote transgender education and equality. This approach will pave the way for a more inclusive society that recognizes and values the rights of all individuals, regardless of their gender identity.
Optimal semiclassical regularity of projection operators and strong Weyl law
Authors: Lafleche Laurent
Published: May 2024

Projection operators arise naturally as one-particle density operators associated to Slater determinants in fields such as quantum mechanics and the study of determinantal processes. In the context of the semiclassical approximation of quantum mechanics, projection operators can be seen as the analogue of characteristic functions of subsets of the phase space, which are discontinuous functions. We prove that projection operators indeed converge to characteristic functions of the phase space and that in terms of quantum Sobolev spaces, they exhibit the same maximal regularity as characteristic functions. This can be interpreted as a semiclassical asymptotic on the size of commutators in Schatten norms. Our study answers a question raised in Chong et al. [J. Eur. Math. Soc. (unpublished) (2024)] about the possibility of having projection operators as initial data. It also gives a strong convergence result in Sobolev spaces for the Weyl law in phase space.
The multi-scale polarizable pseudo-particle solvent coarse-grained approach: From NaCl salt solutions to polyelectrolyte hydration
Authors: Masella Michel , Léonforté Fabien
Published: May 2024

We discuss key parameters that affect the reliability of hybrid simulations in the aqueous phase based on an efficient multi-scale coarse-grained polarizable pseudo-particle approach, denoted as pppl, to model the solvent water, whereas solutes are modeled using an all atom polarizable force field. Among those parameters, the extension of the solvent domain (SD) at the solute vicinity (domain in which each solvent particle corresponds to a single water molecule) and the magnitude of solute/solvent short range polarization damping effects are shown to be pivotal to model NaCl salty aqueous solutions and the hydration of charged systems, such as the hydrophobic polyelectrolyte polymer that we have recently investigated [Masella et al., J. Chem. Phys. 155, 114903 (2021)]. Strong short range damping is pivotal to simulate aqueous salt NaCl solutions at moderate concentration (up to 1.0M). The SD extension (as well as short range damping) has a weak effect on the polymer conformation; however, it plays a pivotal role in computing accurate polymer/solvent interaction energies. As the pppl approach is up to two orders of magnitude computationally more efficient than all atom polarizable force field methods, our results show it to be an efficient alternative route to investigate the equilibrium properties of complex charged molecular systems in extended chemical environments.
Exploring edge states in square–octagon moiré lattice
Authors: Lu Chengzhen , Han Zhanghua , Cai Yangjian , Gao Yuanmei , Wen Zengrun
Published: May 2024

Moiré lattices, achieved by the superposition of two or more twisted identical periodic lattices, are of interest to various fields because they provide additional degrees of freedom. Here, we theoretically and experimentally study the edge states in a square–octagon moiré lattice. This moiré lattice is created by superimposing two identical square sublattices with an antiphase and a special twist angle. Five different edges, named type-I zigzag edge, type-II zigzag edge, type-I bearded edge, type-II bearded edge, and armchair edge, are explored. Through band structure analysis and numerical simulation of edge excitation, we find that all five edges support edge states. The topological property of the type-I edge states is verified by calculating the 2D polarization of the lattice. Furthermore, the edge mode distribution manifests that multiple bands support identical edge states at the armchair and type-II bearded edges. In the experiment, the moiré lattice is generated by the CW-laser-writing technique, thereby observing all the edge states with corresponding edge excitations. This study broadens the understanding of edge states in the coupled moiré photonic lattices and provides a new platform for exploring topological physics.
Directly driven magnetized fast-ignition targets with steep density gradients for inertial fusion energy
Authors: Sefkow A. B. , Logan B. G. , Tabak M.
Published: May 2024

The development of advanced targets capable of achieving ignition with improved energy gain at lower driver energies is one of four key technical challenges to be solved in order to realize economical inertial fusion energy. We report the minimum energy necessary for a small hemispherical mass of fast-ignited high-density deuterium–tritium fuel to explosively ignite a significantly larger hemispherical mass of assembled cold fuel with much lower mass density, both with and without a flux-compressed magnetic field connecting the two regions. With the magnetic field, the burn rate improves, and lower energy states become more effective. The imploded fuel reservoir available in the lower-density, larger-mass region of the steep density gradient determines whether the fusion yield is several hundred MJ or up to a few GJ. We report a case wherein the cold reservoir ignited and produced high gain with the assistance of only ∼700 kJ of hotspot yield, an amount that has already been demonstrated as feasible in laboratory experiments using indirect-drive targets.
Self-calibrated atom-interferometer gyroscope by modulating atomic velocities
Authors: Chen Hong-Hui , Yao Zhan-Wei , Lu Ze-Xi , Lu Si-Bin , Jiang Min , Li Shao-Kang , Chen Xiao-Li , Sun Chuan , Mao Yin-Fei , Li Yang , Li Run-Bing , Wang Jin , Zhan Ming-Sheng
Published: May 2024

Atom-interferometer gyroscopes have attracted much attention for their long-term stability and extremely low drift. For such high-precision instruments, self-calibration to achieve an absolute rotation measurement is critical. In this work, we propose and demonstrate the self-calibration of an atom-interferometer gyroscope. This calibration is realized by using the detuning of the laser frequency to control the atomic velocity, thus modulating the scale factor of the gyroscope. The modulation determines the order and the initial phase of the interference stripe, thus eliminating the ambiguity caused by the periodicity of the interferometric signal. This self-calibration method is validated through a measurement of the Earth’s rotation rate, and a relative uncertainty of 162 ppm is achieved. Long-term stable and self-calibrated atom-interferometer gyroscopes have important applications in the fields of fundamental physics, geophysics, and long-time navigation.
Sensitive, accurate, and high spatiotemporal resolution photonic thermometry
Authors: Hassan Sakib , Ingabire Jeannette , Zhao Xuan , Asfouri Joseph , Robinson Jacob T.
Published: May 2024

Real-time temperature monitoring with high accuracy and spatiotemporal resolution is critical for many biological applications, including disease diagnosis, drug delivery, and biomedical research. However, traditional methods for measuring temperature in biological systems present difficulties for a variety of reasons, such as slow response time, limited spatial resolution, low amplitude, and susceptibility to electromagnetic interference. Most importantly, in many cases, the thermal mass of temperature probes limits the accuracy and speed of measurement significantly. Here, we show that photonic microring resonators (MRRs) can be used for sensitive, precise, and high spatiotemporal resolution measurement of temperature in the biological milieu. The high refractive index of Si MRR and negligible thermal mass enable sensitive, ultrafast, and accurate temperature transients. By using a double resonator circuit, we demonstrate that MRR sensors can measure temperature with a 1 mm spatial resolution. We then show that MRR yields more accurate results than fiber optic probes for measuring temperature transients. Finally, we demonstrate the localized temperature measurement capability of MRRs in mouse brain tissue heated by superparamagnetic nanoparticles in an alternating magnetic field. This compact, lab-on-chip photonic temperature sensing platform holds great promise for continuous monitoring of temperature in critical biological and biomedical applications.
Modeling a neurological disorder as the result of an operator acting on the brain: A first sketch based on network channel modeling
Authors: Mannone Maria , Fazio Peppino , Marwan Norbert
Published: May 2024

The brain is a complex network, and diseases can alter its structures and connections between regions. Therefore, we can try to formalize the action of diseases by using operators acting on the brain network. Here, we propose a conceptual model of the brain, seen as a multilayer network, whose intra-lobe interactions are formalized as the diagonal blocks of an adjacency matrix. We propose a general and abstract definition of disease as an operator altering the weights of the connections between neural agglomerates, that is, the elements of the brain matrix. As models, we consider examples from three neurological disorders: epilepsy, Alzheimer–Perusini’s disease, and schizophrenia. The alteration of neural connections can be seen as alterations of communication pathways, and thus, they can be described with a new channel model.
Experimental concept validation of a proton therapy range verification system using scattered proton measurements
Authors: Sato S. , Yokokawa H. , Sagisaka M. , Okazaki Y. , Iwashita R. , Yoshida S. , Tanaka K. S. , Yamamoto S. , Yamashita T. , Kobashi Y. , Kataoka J.
Published: May 2024

In recent years, the application of positron emission tomography (PET) for the dose range verification of proton therapy has been proposed. However, the positron distribution is determined by the nuclear reaction cross section; hence, PET may not accurately reflect the dose range primarily influenced by ionization. Consequently, a proton dose range verification system based on scattered proton measurements has been suggested owing to the similarity in the reaction cross section between Rutherford scattering and ionization. While previous investigations have only verified the feasibility of dose range estimation through simple simulations, the objective of this study is to demonstrate this feasibility through experimental investigation. In this paper, we established an experimental framework for capturing scattered protons and introduced an algorithm that compares measured signal patterns with a reference database to estimate the dose range. A therapeutic beam was irradiated onto the abdominal region of a human phantom, and scattered protons were measured using scintillation detectors placed on the phantom surface. Consequently, the dose range was estimated with error margins of 4.22 ± 3.68 and 0.60 ± 1.03 mm along the beam axis and perpendicular directions to the Bragg peak, respectively. While providing the same level of Bragg peak positioning accuracy as conventional methods, our system features small size, cost-effectiveness, and system simplicity. One notable limitation of our method is the challenge in achieving precise detector positioning, which is crucial for accurate dose range estimation. Future research will focus on improving detector-position accuracy and exploring advanced algorithms for signal analysis to further refine dose range estimations.
Nonlinear hydrological time series modeling to forecast river level dynamics in the Rio Negro Uruguay basin
Authors: Duque Johan S. , Santos Rafael , Arteaga Johny , Oyarzabal Ricardo S. , Santos Leonardo B. L.
Published: May 2024

Floods significantly impact the well-being and development of communities. Hence, understanding their causes and establishing methodologies for risk prevention is a critical challenge for effective warning systems. Complex systems such as hydrological basins are modeled through hydrological models that have been utilized to understand water recharge of aquifers, available volume of dams, and floods in diverse regions. Acquiring real-time hydrometeorological data from basins and rivers is vital for establishing data-driven-based models as tools for the prediction of river-level dynamics and for understanding its nonlinear behavior. This paper introduces a hydrological model based on a multilayer perceptron neural network as a useful tool for time series modeling and forecasting river levels in three stations of the Rio Negro basin in Uruguay. Daily time series of river levels and rainfall serve as the input data for the model. The assessment of the models is based on metrics such as the Nash–Sutcliffe coefficient, the root mean square error, percent bias, and volumetric efficiency. The outputs exhibit varying model performance and accuracy during the prediction period across different sub-basin scales, revealing the neural network’s ability to learn river dynamics. Lagged time series analysis demonstrates the potential for chaos in river-level time series over extended time periods, mainly when predicting dam-related scenarios, which shows physical connections between the dynamical system and the data-based model such as the evolution of the system over time.
Expulsion of hydrogen negative ions by the anode layer of negative space charge from Penning discharge with metal hydride cathodes
Authors: Sereda I. , Hrechko Y. , Azarenkov M.
Published: May 2024

The method of expulsion of hydrogen negative ions in the axial direction by a negative space charge formed in the plasma of Penning discharge with metal hydride cathodes is discussed. The plasma is produced on hydrogen, which is stored in metal hydride cathodes and injected locally into the discharge cell without any external gas supply due to ion current impact from plasma. The process of nonequilibrium desorption resulted in high vibrational excitation of H2 molecules, which greatly increases the efficiency of H− ion production. The method of efficient expulsion of H− ions depends on the external magnetic field. At a high magnetic field, it is performed by the supply of negative electric bias of the opposite cathode, but at a low one, H− ions are pushed out by the negative space charge of the anode layer, which expands toward the axis. The impact of both methods is considered in the case of DC discharge and in pulsating regime implementation.
Imaging of the vascular distribution of the outer ear using optical coherence tomography angiography for highly accurate positioning of a hearable sensor
Authors: Hong Juyeon , Seong Daewoon , Kang Dongwan , Kim Hyunmo , Jang Jeong Hun , Jeon Mansik , Kim Jeehyun
Published: May 2024

Novel hearable technology is securely and comfortably positioned within the ear canal minimizing inaccuracies caused by accessory movements during activities. Despite extensive research on hearable technologies within the outer ear, there is a lack of research in the field of vascular imaging and quantitative analysis in the outer ear in vivo, which is one of the crucial factors to select the appropriate sensor position. Therefore, in this paper, we introduced optical coherence tomography angiography (OCTA)-based qualitative and quantitative analyses to visualize the inner vasculature of the outer ear to acquire vascular maps for microvascular assessments in vivo. By generating maximum amplitude projection images from three-dimensional blood vascular volume, we identified variations of blood vessel signal caused by the different biological characteristics and curvature of the ear among individuals. The performance of micro-vascular mapping using the proposed method was validated through the comparison and analysis of individual vascular parameters using extracted 20 vascular-related variables. In addition, we extracted pulsatile blood flow signals, demonstrating its potential to provide photoplethysmographic signals and ear blood maps simultaneously. Therefore, our proposed OCTA-based method for ear vascular mapping successfully provides quantitative information about ear vasculature, which is potentially used for determining the position of system-on-chip sensors for health monitoring in hearable devices.
Characterization of ECRH plasmas in TOMAS
Authors: Buermans J. , Adriaens A. , Brezinsek S. , Crombé K. , Desmet N. , Dittrich L. , Goriaev A. , Kovtun Yu. , López-Rodríguez L. D. , Petersson P. , Van Schoor M.
Published: May 2024

To improve the plasma performance and control the density and plasma quality during the flat top phase, wall conditioning techniques are used in large fusion devices like W7-X and in JT60-SA. To study the performance of electron cyclotron wall conditioning, numerous experiments were performed on the TOroidally MAgnetized System, which is operated by LPP-ERM/KMS at the FZ-Jülich. It is a facility designed to study plasma production, wall conditioning, and plasma–surface interactions. The produced electron cyclotron resonance heating plasmas are characterized in various conditions by density and temperature measurements using a movable triple Langmuir probe in the horizontal and the vertical direction, complemented by video and spectroscopic data, to obtain a 2D extrapolation of the plasma parameters in the machine. A way to calibrate the triple Langmuir probe measurements is also investigated. These data can be used to determine the direction of the plasma drift in the vessel and identify the power absorption mechanisms. This will give more insight in the plasma behavior and improve the efficiency of wall conditioning and sample exposure experiments.
Promote or inhibit turbulence drag reduction behavior of surfactant solutions with different micelle structures by certain nanoparticle addition
Authors: Li Xiaoping , Wang Huajie , Zhang Yun , Sun Shengpei , Zhou Yu , Lu Xinlong , Jing Dengwei
Published: May 2024

The micelle structure of surfactant is easy to be destroyed in the flow process resulting in a decrease in its drag reduction (DR) efficiency; therefore, how to strengthen the stability of the micelle structure during the flow process and thus improve the drag reduction efficiency deserves intensive research. In this work, by comparing a variety of nanoparticles, hydrophobic silica nanoparticles were selected as the best additive to enhance the turbulence drag reduction efficiency of surfactant solution with spherical micelle structure. The experimental results also demonstrated that the hydrophobic silica nanoparticles had a reinforcing effect on anionic, cationic, nonionic, and zwitterionic surfactant solutions with the same concentration (dominated by spherical micelles), and the optimal nanoparticle addition concentration and maximum drag reduction rate were obtained. Meanwhile, the effect of silica nanoparticles on the turbulence drag reduction efficiency of surfactant solutions with different micelle structures was evaluated by inducing the surfactant micelle structure change. It was shown that the hydrophobic silica nanoparticles had a strengthening effect on the turbulence drag reduction performance of surfactant solutions with spherical micelle structure, while they had an inhibiting effect on the turbulence drag reduction performance of surfactant solutions with worm-like micelle structure. The change in solution viscoelasticity indicated that the decrease in viscoelasticity was the main reason for the decrease in drag reduction efficiency of surfactant solution with worm-like micelle structure when silica nanoparticles were added. A mechanism for the interaction of hydrophilic/hydrophobic silica nanoparticles with spherical micelles and wormlike micelle structures was finally discussed and proposed.
Insights into shock velocity variation in double-diaphragm shock tubes
Authors: Kashif Touqeer Anwar , Subburaj Janardhanraj , Khan Md Zafar Ali , Farooq A.
Published: May 2024

A comprehensive understanding of shock formation and propagation in shock tubes is crucial for their diverse applications. The shock velocity in single-diaphragm shock tubes, characterized by initial acceleration and subsequent attenuation due to viscous effects, has been extensively investigated. However, limited studies exist on the double-diaphragm mode of operation. In this study, shock tube experiments were conducted using helium at pressures of 10–60 bar as driver gas and argon at pressures of 100–600 Torr as driven gas. The shock velocity profiles in the double-diaphragm mode show a sequence of acceleration and deceleration stages of the shock front, strongly influenced by the driver-to-driven pressure ratios (P41) and the pressure in the intermediate section (Pmid). Particularly, at high values of P41, peak shock velocities can exceed those measured near the end wall by about 12%. Large axial temperature gradients arise in the driven gas due to the accelerating and decelerating shock. Selecting appropriate diaphragms to maintain the intermediate section's pressure close to the value of the driver pressure can reduce peak shock velocities and post-shock temperatures. An in-house one-dimensional (1D) weighted essentially non-oscillatory scheme-based code was utilized to analyze wave interactions in the shock formation region, revealing that the post-shock gas behind the secondary diaphragm and inhibition of the primary diaphragm's opening and subsequent reopening can lead to unique shock profiles in double-diaphragm shock tubes. These insights deepen our understanding of wave propagation in shock tubes and suggest ways to mitigate undesirable effects in double-diaphragm shock tubes.
High-temperature tensile behavior and constitutive model in Co-free Fe40Mn20Cr20Ni20 high-entropy alloy
Authors: Li Fan , Han Lina , Wang Xuejiao , Lan Aidong , Qiao Junwei
Published: May 2024

High-entropy alloys (HEAs) have attracted widespread attention from scholars as a new type of material employed in extreme environments. However, as a main kind of HEAs, many face-centered cubic single-phase HEAs are restricted in industrial applications due to their lower yield strength and high cost when containing expensive elements such as Co. In this study, dispersion strengthening by heat treatment was introduced in low-cost Co-free Fe40Mn20Cr20Ni20 HEA to improve its strength, and its high-temperature tensile behavior and constitutive model were studied to explore its potential application at high temperatures. It is found that when subjected to quasi-static room-temperature stretching, the heat-treated sample exhibits a yield strength of 534 MPa and a tensile plasticity of 26.8%. In addition, the tensile behavior of samples after heat treatment was investigated at high temperature (573–873 K) and low strain rate (10−3–10−1 s−1). The results suggest that the yield strength decreases with increasing temperature and decreasing strain rate. Moreover, at 873 K and 10−3 s−1, the electron backscatter diffraction system and x-ray diffraction results of the deformed sample indicate that the softening curve is driven from the recovery of materials. Finally, the flow stress was predicted using the Arrhenius equation and Artificial Neural Network model (ANN), and the two models were assessed using the average absolute relative error and coefficient of correlation (R). The results showed that the ANN had higher accuracy.
Diagnosis of unsteady disturbance characteristics induced by the tip leakage vortex in a compressor based on data-driven modal decomposition methods
Authors: Sun Lihui , Yang Jun , Liu Xiaohua , Sun Dakun , Dong Xu
Published: May 2024

The structural information about the tip leakage vortex at the design point remains largely unknown. Here, the dynamic mode decomposition method is utilized to visualize the main coherent structures corresponding to unsteady disturbance frequencies induced by the tip leakage vortex of an isolated rotor at the design point. The results show that the tip clearance size has a significant impact on unsteady disturbance characteristics at the blade tip region. The flow field within the blade tip region can be categorized into four distinct regions: the formation region of the main tip leakage vortex (MTLV), the formation region of the secondary tip leakage vortex (STLV), the merging zone where the MLTV and the STLV interact, and the vortex shedding zone induced by the leakage vortex breakdown. The disturbance peak in the frequency domain decreases from 121.3 RF to 70.96 RF as the tip clearance size increases from 1.5% blade height to 2%, resulting in a reduction of 41.36%. The increase in the tip clearance size amplifies unsteady disturbances caused by the MTLV and STLV. The STLV exhibits more pronounced oscillatory characteristics than the MTLV. The unsteady disturbance induced by the MLTV mainly occurs at around 0.5 blade passing frequency (BPF). In contrast, high-frequency unsteady disturbances (>1 BPF) in the flow field are caused by vortex shedding resulting from the interaction and collision between the STLV and the MTLV. A better understanding of the unsteady disturbance characteristics induced by leakage vortex benefits the study of stall warning technology.
Detection of Dirac fermions in capped SnTe film via magnetotransport measurements
Authors: de Castro S. , Abramof E. , Rappl P. H. O. , Peres M. L.
Published: May 2024

In this work, we present the investigation of the magnetotransport properties of a capped SnTe film, grown by molecular beam epitaxy, using Shubnikov–de Haas oscillations for the detection of Dirac fermions. The cap layer used was a 10 nm thick Sn0.98Eu0.02Te film, which can also contribute to the transport such that it is mandatory to isolate its contribution from the electrical transport measured in the sample. To separate the contribution from both layers, photoconductivity measurements were performed. A detailed analysis of the Shubnikov–de Haas oscillations is carried out using theoretical expressions and building the Landau-level indexation. We found that Dirac fermions are detected in the SnTe layer, while the cap layer contributes with trivial fermions, protecting SnTe against deterioration due to exposure to the atmosphere.
Ultrafast nanometric resolution spatiotemporal measurement of ambipolar diffusivity and carrier-phonon coupling in doped and undoped silicon
Authors: Segovia Mauricio , Xu Xianfan
Published: May 2024

Understanding and determination of the ambipolar diffusivity of a semiconductor is fundamental for predicting device behavior and optimizing its performance. Ultrafast pump-probe measurements allow for the determination of energy carrier dynamics with sub-picosecond resolution. Due to the inherent diffusive nature of carriers, measurements with a high spatial resolution are needed, in addition to the traditional pump-probe system, to determine not only the carrier dynamics but also the spatial extent caused by carrier diffusion as well. In this work, a spatiotemporal measurement system with ultrafast temporal and nanometric spatial resolution, together with a comprehensive transport model, is used to determine the ambipolar diffusivity and carrier-phonon energy coupling time in both undoped and doped silicon. The results show that as the carrier density increases, the measured ambipolar diffusivity decreases with minimal variation in the carrier-phonon energy coupling time. In general, this work demonstrates an optical-based method for determining ambipolar diffusivity in a semiconductor material.
Fully coupled discrete element method for graded particles transport in pipes
Authors: Zhou You , Shi Huabin , Li Jiaxing , Chen Xin
Published: May 2024

Hydraulic conveying of graded particles is much more complex than that of uniform particles but is not fully understood. A fully coupled computational fluid dynamics–discrete element method model is established for the hydraulic conveying of graded particles, which integrally considers the particle–fluid and particle–particle interactions and turbulence modulation from particles. The proposed model accounts for the stochastic motion of particles by the discrete random walk method and applies the diffusion averaging algorithm to obtain particle concentration in arbitrary cells for smooth and cell-independent data fields on unfavorable cells (fluid cell size ≤ particle size). The particle–fluid drag force is applied to slurry flows through densely packed particle beds due to the consideration of porosity modification. The proposed model well performs in simulating the hydraulic conveying of dense graded particles. Dynamics in slurry mixtures of bi-disperse particles are investigated regarding different particle size compositions. The results show obvious stratification between coarse and fine particles, e.g., fine particles settling at the pipe bottom elevate the coarse particles and form a “lubrication layer” with high velocity. The torque caused by particle–particle/wall contact is greater than the torque caused by the fluid. The pipe cross section is divided into four regions according to the particle angular velocity. The effect of particle concentration on liquid motion is small because the difference in local particle concentration is relatively small, but the maximum pressure drop corresponds to a critical particle size composition.
Deep cavity noise suppression by exploiting aeroacoustic–structural interaction of multiple elastic panels
Authors: Naseer Muhammad Rehan , Arif Irsalan , Leung Randolph C. K. , Abdullah Ali
Published: May 2024

This paper reports a numerical study of a novel methodology for passive suppression of deep cavity noise by means of strategically designed and arrangements of multiple elastic panels and examines its underlying aeroacoustic–structural interaction physics. The study is conducted with a freestream, at Mach number 0.09 and Reynolds number of 4 × 104 based on the cavity length, past a two-dimensional cavity by means of direct aeroacoustic simulation coupled with a panel dynamic solver in monolithic fashion. For each cavity-panel configuration, the fluid-loaded panel natural frequencies are harmonized with the characteristic aeroacoustic processes of the original/modified cavity aeroacoustic feedback loop. This promotes panel aeroacoustic-structural resonance for absorption of feedback flow and acoustic fluctuation energy for achieving less eventual cavity noise. The most effective configuration gives a remarkable noise power reduction by 15 dB from a rigid cavity. Inadvertently, it reduces cavity drag by almost 15%. Simultaneous reduction of both cavity noise and drag is unprecedented among similar attempts in the literature. In-depth spatiotemporal analyses of aeroacoustic–structural interaction results elucidate the intricate interplay between cavity flow, panel vibration responses, and cavity acoustic modes, leading to noise reduction in all cavity-panel configurations studied. Essentially, the vertical panel acts to curtail the efficacy of coupling between growing shear layer and cavity acoustic modes whose sustenance is further impeded by an acoustically induced resonant panel at the cavity bottom. The proposed methodology is confirmed to be feasible yet effective, which holds great potential for fluid-moving applications in which a quiet and energy-efficient cavity configuration is desired.
High-output ∼3
μ
m MIR pulsed laser enabled by surface state regulation in PtTe2 optical switch
Authors: Liu Shande , Jin Yicheng , Lv Jiawen , Li Kuan , Dong LuLu , Wang Peifu , Liu Junting , Lu Junpeng , Ni Zhenhua , Zhang Baitao
Published: May 2024

Mid-infrared (MIR) pulsed lasers operating in the ∼3 μm region play a crucial role in various applications, including molecular spectroscopy, ultrafast molecular imaging, and laser-assisted surgery. Despite recent advancements in MIR gain platforms, a notable technological challenge remains in the absence of an effective optical Q-switch. Here, a remarkable optical Q-switch in the 3 μm region based on a Dirac semimetal PtTe2 saturable absorber is realized. By modulating the surface state of PtTe2, the pulsed laser exhibited an increase in average power, escalating from 521 to 588 mW, accompanied by a significant decrease in pulse width from 368 to 187 ns. Nondegenerate pump–probe measurements showed that the recombination rate of the photocarrier in thinner PtTe2 nanoplates was effectively accelerated, primarily attributed to the substantial increase in surface state density, leading to better saturable absorption performance. As the thickness of the PtTe2 nanoplates decreases, the nonsaturable loss decreases from 12% to 3%, while the modulation depth increases from 6% to 12%. The enhanced ultrafast nonlinear absorption enables flexible modulation of saturation absorption parameters, which endows high-performance MIR pulsed laser generation.
Study on a rotational symmetry structure pulse forming network with low-impedance for compact pulse drivers
Authors: Yu Ruixin , Yang Shuang , Gao Jingming , Chen Rong , Sun Yijie , Li Diangeng , Yang Hanwu
Published: May 2024

A pulse forming network (PFN) is a significant component, contributing a lot to the overall dimension of pulse generators. In order to both reduce the size of PFN and improve the output waveform quality, this paper proposes a compact low-impedance PFN with a rotational symmetry structure. The PFN consists of four groups of Blumlein pulse forming units (PFUs) connected in parallel along the angular direction, and the spline curve structure is applied in each PFU, which achieves a higher space utilization rate. The theoretical maximum energy density of PFN is 6.6 J/L as the dimensions of PFN are φ500 × 138 mm. Field-circuit co-simulation is carried out based on the spatial model of PFN and the double switch modulation circuit to analyze the effects of switch delay time (time between main switch and steep discharge switch), as well as the output port position affecting the output pulse waveform. The results show that the PFN is appropriate to achieve quasi-square wave pulse modulation as the switch delay time is 290 ns with the output port positioned at the periphery. The verification experiments are also carried out. The results show that the PFN can generate a quasi-square wave pulse with an output voltage of 49.6 kV, a pulse width of 83 ns, and a peak power of 1 GW on a matched load. The output pulse exhibits a distinct flat top, with the fluctuation of the plateau being less than 3%.
Weak and strong chirality-anomaly-manipulations in a superconducting Weyl semimetal sandwich structure
Authors: Li Mengyao , Wang Zhouyu , Ding Zixuan , Tao Yongchun , Huang Fengliang
Published: May 2024

We investigate the quantum interference of the electron–hole conversions from the two interfaces in a Weyl semimetal (WSM)-based hybrid structure, in which a superconducting WSM is sandwiched in between two normal ones. The quantum interference is characterized by the chirality-anomaly-manipulation (CAM). It is found that only low energy is in favor for s-wave BCS pairing states. The Andreev reflection (AR) chirality blockade can be tuned by the stagger angle α for the relative orientation of paired Weyl points, accompanied by an AR bipolar chirality diode. Thus, a strong CAM is indicated for the electron–hole conversion. However, the Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) pairing states have no energy preference, with the weak and strong CAMs being near and far away from the zero energy, respectively. More interestingly, a perfect AR with the normal reflection suppressed thoroughly can be obtained at any α as a result of the FFLO paring with the same chirality. In addition, the conductance or noise power, which incorporates the contributions of the two paired Weyl nodes, not only, in turn, embodies the respective features of their contributions but also can be experimentally measured to discern between the BCS and FFLO paring states.