bluuebunny/crossref_metadata_2025 huggingface dataset:
A push–pull FVF LDO with full‐spectrum PSR and fast transient response
Authors: Zheng Heng , Liu Baixin , Wang Chen , Wang Xukun , Zhou Bo
Published: February 2024

A push–pull low‐dropout regulator based on flipped voltage follower is proposed and designed in 65 nm CMOS, which has a push‐current mode and a pull‐current one. The push‐current mode with 1.2‐V input and 1‐V output effectively drives load circuits that are sensitive to supply noise. The pull‐current one with 1.2‐V input and 0.2‐V output effectively drives load circuits that are sensitive to ground noise. Both operating modes feature full‐spectrum power supply rejection (PSR) below −12 dB and achieve 2.4‐ns transient response time over load current (IL) of 10 µA to 20 mA. The presented design achieves a fast transient response and a high‐frequency PSR with a low‐gain fast loop (loop‐I), and enhances the low‐frequency PSR and the line/load regulation with a high‐gain slow loop (loop‐II). Furthermore, the circuit features a load regulation less than 0.09 mV/mA over IL of 10 µA to 20 mA and a line regulation less than 0.01 mV/mV, within a 120‐mV ripple applied to supply/ground. This design consumes a 58‐µA quiescent current (IQ) in both push‐current and pull‐current modes. The low‐dropout regulator works well over the load capacitor (CL) of 0 to 30 pF.
Solving differential‐algebraic equations in power system dynamic analysis with quantum computing
Authors: Tran Huynh T. T. , Nguyen Hieu T. , Vu Long T. , Ojetola Samuel T.
Published: February 2024

Power system dynamics are generally modeled by high dimensional non‐linear differential‐algebraic equations (DAEs) given a large number of components forming the network. These DAEs' complexity can grow exponentially due to the increasing penetration of distributed energy resources, whereas their computation time becomes sensitive due to the increasing interconnection of the power grid with other energy systems. This paper demonstrates the use of quantum computing algorithms to solve DAEs for power system dynamic analysis. We leverage a symbolic programming framework to equivalently convert the power system's DAEs into ordinary differential equations (ODEs) using index reduction methods and then encode their data into qubits using amplitude encoding. The system non‐linearity is captured by Hamiltonian simulation with truncated Taylor expansion so that state variables can be updated by a quantum linear equation solver. Our results show that quantum computing can solve the power system's DAEs accurately with a computational complexity polynomial in the logarithm of the system dimension. We also illustrate the use of recent advanced tools in scientific machine learning for implementing complex computing concepts, that is, Taylor expansion, DAEs/ODEs transformation, and quantum computing solver with abstract representation for power engineering applications.
Vorzeitige Plazentalösung
Authors: Hildebrandt Sven , Göbel Esther
Published: February 2024

Eine Ablösung der Plazenta vor der Geburt des Kindes gehört zu
den schlimmsten geburtshilflichen Notfällen und ist mit hoher kindlicher
Mortalität verbunden. Prof. Dr. med. Sven Hildebrandt und Hebamme Esther
Göbel ergründen in diesem Fachartikel, wie die drastische
Zunahme der Komplikation in den letzten Jahren zu erklären sein
könnte, bei welchen Symptomen Hebammen und Geburtshelfer an eine
vorzeitige Plazentalösung denken sollten und wie sie im Akutfall richtig
handeln.
Research Progress of Natural Product Photosensitizers in Photodynamic Therapy
Authors: Zhou Xiaoxia , Ying Xufang , Wu Linjie , Liu Liqin , Wang Ying , He Ying , Han Min
Published: February 2024

Photodynamic therapy is a noninvasive cancer treatment that utilizes photosensitizers to generate reactive oxygen species upon light exposure, leading to tumor cell apoptosis. Although photosensitizers have shown efficacy in clinical practice, they are associated with certain disadvantages, such as a certain degree of toxicity and limited availability. Recent studies have shown that natural product photosensitizers offer promising options due to their low toxicity and potential therapeutic effects. In this review, we provide a summary and evaluation of the current clinical photosensitizers that are commonly used and delve into the anticancer potential of natural product photosensitizers like psoralens, quinonoids, chlorophyll derivatives, curcumin, chrysophanol, doxorubicin, tetracyclines, Leguminosae extracts, and Lonicera japonica extract. The emphasis is on their phototoxicity, pharmacological benefits, and effectiveness against different types of diseases. Novel
and more effective natural product photosensitizers for future clinical application are yet to be explored in further research. In conclusion, natural product photosensitizers have potential in photodynamic therapy and represent a promising area of research for cancer treatment.
Practice Patterns for Managing Recurrent Glioblastoma Multiforme
Authors: Bajaj Jitin , Kedia Shweta , Sharma Arvind , Gupta Pankaj , Ansari Mohammad , Deora Harsh , Garg Kanwaljeet , Dash Chinmaya , Madhugiri Venkatesh S. , Das Kuntal Kanti , Tripathi Manjul , Singh Deepak K. , Raju Subodh , Jagetia Anita , Vazhayil Vikas , Singh Manmohan , Mittal R.S. , Gupta Subhash , Yadav Y.R. , Ramzan Altaf , Umredkar Alok , Jha Deepak Kumar , Mahapatra A.K.
Published: February 2024

Introduction Glioblastoma multiforme (GBM) is a devastating form of cancer with a poor prognosis despite available treatments. Managing recurrent GBM remains challenging and lacks guidelines. This study aims to provide practice patterns for managing recurrent GBMs in India.

Methods A panel of experts was assembled to develop practice patterns using the Delphi technique. Their responses were analyzed anonymously to ensure impartiality and generate recommendations. The statements were intended to be nonbinding and focused on promoting best practices in the field, without legal or regulatory authority.

Results A total of 23 experts participated in the study, providing their opinions on various aspects of managing recurrent GBM. Consensus was achieved on individualized and multidisciplinary management as the preferred approach. Surgery in combination with other treatments was found to impact survival in patients older than 65 years, with re-surgery and adjuvant radiation and chemotherapy being the preferred options. Gadolinium-enhanced magnetic resonance imaging (MRI) brain with spectroscopy and diffusion-weighted imaging was favored. Molecular profiling was considered significant, with O6-methylguanine DNA methyltransferase methylation being most relevant. Surgery was recommended for recurrent GBMs, primarily based on Karnofsky's performance score (KPS). Surgical adjuncts such as neuronavigation and intraoperative MRI were considered valuable. Radiation therapy, specifically stereotactic radiosurgery, was recommended for selected cases, while opinions on re-chemotherapy were divided. Palliative care was deemed important.

Conclusion This study presents practice patterns for managing recurrent GBM in India, providing standardized recommendations for practice. By implementing these, clinicians can make informed decisions, leading to improved patient outcomes and reduced variability in the management of recurrent GBM.
Implantation of a Newly Designed Supratarsal Gold Weight versus the Traditional Pretarsal Model for the Correction of Long-standing Paralytic Lagophthalmos: A Retrospective Cohort Study
Authors: Lailaksiri Natthiya , Wanichsetakul Pawarit , Saonanon Preamjit
Published: February 2024

Background The study determined to compare the clinical outcomes of traditional gold weight implantation for the correction of paralytic lagophthalmos with those of a newly designed model.

Methods In this retrospective cohort study, we enrolled 30 patients (76% females; average age 60.8 ± 12 years) with facial palsy who underwent implantation of either the traditional pretarsal gold weight (PT group; n = 15) or a new supratarsal model (ST group; n = 15) from May 2014 to April 2019. The main outcome measures were the 12-month postoperative weight prominence, weight migration, improvement of lagophthalmos, upper eyelid contour, and upper eyelid ptosis. The secondary outcome was long-term (24 months) reoperative rate.

Results The new model group had significantly better eyelid contour (risk ratio [RR] 3.16, 95% confidence interval [CI] 1.62–6.15, p = 0.001), less weight prominence (RR 1.74, 95% CI 1.13–2.70, p = 0.013), less weight migration (RR 1.31, 95% CI 1.12–1.54, p = 0.001), and less eyelid ptosis (RR 2.36, 95% CI 1.21–4.59, p = 0.011) than the traditional model group. Improvement of lagophthalmos was not statistically significant between the two groups (RR 1.44, 95% CI 0.72–2.91, p = 0.303). The 24-month reoperative rate was 53.3% in the PT group versus 13.3% in the ST group (RR 2.00, 95% CI 1.15–3.49, p = 0.015).

Conclusion The newly designed supratarsal gold weight showed superior postoperative outcomes than the standard traditional model.
Two Uncommon Cases of Pediatric Transethmoidal–Transnasal Encephaloceles with a Review of Literature
Authors: Acharya Abhijit , Senapati Satya Bhusan , Panigrahi Souvagya , Deo Rama Chandra , Mahapatra A. K.
Published: February 2024

Encephaloceles are defined as the herniation of brain matter beyond the confines of the skull bone through a defect on the cranium or face. The encephaloceles are classified into different categories as per onset as congenital or traumatic, as per contents as meningocele, meningoencephalocele, and hydromeningoencephalocele, and as per anatomical location into frontoethmoid, basal, occipital, and cranial vault. Transethmoidal encephalocele is a rare type of encephalocele with a very few patients reported in the literature to date. We are presenting two cases of transethmoidal–transnasal encephalocele in the pediatric age group with one being congenital and other traumatic in onset. The first child presented with a mass visible inside the nasal cavity since birth with nasal obstruction. The second child presented with a history of trauma 5 years back followed by occasional cerebrospinal fluid leak, fever, and nasal stuffiness. Both patients underwent craniotomy and excision of the encephalocele with repair of the defect in the cribriform plate. These two uncommon cases highlight the different onsets of the disease successfully managed surgically.
COVID-19-Related Brief Insomnia in a 13-Year-Old Adolescent Girl
Authors: Serdengeçti Nihal , Tarakçıoğlu Mahmut Cem
Published: February 2024

Neuropsychiatric manifestations that have developed after coronavirus disease 2019 (COVID-19) infection have not been fully clarified yet. Persistent insomnia and consequent significant impairment in daily functioning is an unexpected symptom of COVID-19 infection. In this case report, a 13-year-old female patient who presented with complaint of insomnia starting with COVID-19 infection is discussed. The patient showed significant improvement with melatonin treatment and maintained her wellbeing in the follow-up. Melatonin may be a useful option to treat COVID-19-related brief insomnia in adolescents. Our case report will be a step forward to help clinicians examine the underlying neurovegetative mechanisms, such as sleep, to improve patients wellbeing. HEADINGS: COVID-19. Melatonin. Sleep Initiation and Maintenance Disorders
Spontaneous Rupture of Superficial Femoral Artery Treated Endovascularly Using CO2 Angiography
Authors: Padhi Rasmiranjan , Dhanasekaran Jagadeesan , P. Vinoth
Published: February 2024

Spontaneous rupture of the superficial femoral artery (SFA) is extremely rare. We report an interesting case of an elderly man presented with a history of hearing a click sound in his left lower thigh followed by sudden onset pain, swelling, and discoloration in the left lower limb while coming back from the bathroom. He was a known case of chronic kidney disease, and cirrhosis of the liver with moderate left ventricular (LV) dysfunction. We treated the ruptured SFA using overlapping stent grafts with CO2 angiography. The pseudoaneurysm got thrombosed. The pain and swelling of the left lower limb gradually subsided. The patient went home walking.
Minimizing the Pain of Local Anesthesia Administration in Interventional Radiology with an Anesthetic Portal Technique
Authors: Suttle Dylan , Gill Virpal , Sheeran Daniel , Keefe Nicole , Davis Claire , Patrie James , Angle John F.
Published: February 2024

Objective This article assesses the effectiveness of a standardized local anesthetic (LA) technique designed to minimize the pain of local anesthesia administration in interventional radiology (IR).

Materials and Methods A prospective study compared participants' experience in a control group (n = 63) of random LA administration techniques to a separate experimental group (n = 60) with a standardized technique based on known methods to minimize the pain of LA. Participants in each group were surveyed after LA administration to assess perceived pain and number of times a painful stick was felt. Participants were also asked to compare LA pain to prior experiences with LA, and to compare the overall pain experienced during the procedure to expected pain.

Statistical Analysis Ordinal variable distribution analyses were performed using the Wilcoxon rank sum test. Categorical variable analyses were performed with the Pearson's global exact chi-square test.

Results Pain of LA (mean 1.1 vs. 3.3 on a 0–10 scale, p < 0.001), number of times a painful stick was felt (mean 0.8 vs. 1.9 times, p < 0.001), and overall pain during the procedure (mean 1.5 vs. 3.4 on 0–10 scale, p < 0.001) were significantly less using the standardized versus random techniques. Compared with prior experiences of LA, pain using the standardized technique was less in 77.6%, the same in 22.4%, and more in 0% of patients while pain using the random technique was less in 46.4%, the same in 39.3%, and more in 14.3% of patients (p < 0.05).

Conclusion Severity and frequency of pain from LA administration in IR procedures is minimized using a standardized anesthetic portal technique. This technique may also decrease overall pain experienced during IR procedures as well.
Bystanders’ collective responses set the norm against hate speech
Authors: Zapata Jimena , Sulik Justin , von Wulffen Clemens , Deroy Ophelia
Published: February 2024

Hate speech incidents often occur in social settings, from public transport to football stadiums. To counteract a prevailing passive attitude towards them, governmental authorities, sociologists, and philosophers stress bystanders’ responsibility to oppose or block hate speech. Here, across two online experiments with UK participants using custom visual vignettes, we provide empirical evidence that bystanders’ expression of opposition can affect how harmful these incidents are perceived, but only as part of a collective response: one expressed by a majority of bystanders present. Experiment 1 (N = 329) shows that the silence or intervention of three bystanders affects the harm caused by hate speech, but one bystander does not. Experiment 2 (N = 269) shows this is not simply a matter of numbers but rather one of norms: only unanimous opposition reduces the public perception of the damage created by the incident. Based on our results, we advance an empirical norm account: group responses to hate speech modulate its harm by indicating either a permissive or a disapproving social norm. Our account and results, showing the need to consider responses to hate speech at a collective level, have direct implications for social psychology, the philosophy of language and public policies.
Applying Q-methodology to investigate computer science teachers’ preferences about students’ skills and knowledge for obtaining a degree
Authors: Takács Rita , Takács Szabolcs , Kárász Judit T. , Oláh Attila , Horváth Zoltán
Published: February 2024

Students’ dropout of Computer Science (CS) education is a crucial issue. This study aims to investigate one of the aspects which can help to retain our students. It is vital to examine CS education on the challenge of competence transition within the BSc curriculum from faculty perspectives. Teachers’ expectations about students’ skills and knowledge are important to understand because they influence learning outcomes and teaching methodologies. Acquiring hard skills and professional skills has outstanding significance in preparing students for their future careers. This study uses Q-methodology to identify the different viewpoints on the skills necessary to obtain a CS degree. Teachers from CS bachelor’s programmes at a large European university participated in the study and shared their opinions. The participants were asked to rank the statements along a spectrum of “the most important skill” to “unimportant skill” (containing hard skills as well as soft skills). Factor analysis revealed five factors that are key components to obtaining a degree in CS: 1. analytical and technical skills, 2. teamwork and self-study experience, 3. group programming experience, 4. communication and problem-solving skills, 5. mathematical foundations and process modelling ability. This exploratory study applied a new research instrument and approach to incorporate teachers’ perspectives into research and practice. These findings could help administrators develop new curricula in order to increase students’ retention. We confirmed the need for acquiring professional skills and highlighted the need for designing new programmes which can improve students’ soft skills to prepare them for work in the IT field.
Workplace cyberbullying and social capital among Jordanian university academic staff: a cross-sectional study
Authors: Alrawashdeh Maissa N. , Alsawalqa Rula Odeh , Alnajdawi Ann , Aljboor Rami , AlTwahya Fawzi , Ibrahim Abdullah Mahmod
Published: February 2024

Workplace cyberbullying has harmful psychological, social, and behavioral consequences for employees and employers. This study investigates workplace cyberbullying among academic staff of both sexes at Jordanian universities, to explore their exposure to workplace cyberbullying by colleagues and employers and its correlation with social capital and self-esteem. Data were collected through an anonymous online survey involving Jordanian academic staff. The findings revealed that workplace cyberbullying reduces with increasing social capital. No relationship was detected between workplace cyberbullying and self-esteem. A positive correlation was found between self-esteem and structural social capital. Age, sex, and university sector do not predict academic workplace cyberbullying levels. The results indicate that administrators and policymakers in the Jordanian higher education sector should improve social capital among academics, given its positive implications for self-esteem, organizational life, and the prevention of distress. This strategy is appropriate in the turbulent conditions confronting academics working in a context with an increasingly dominant digital culture.
Understanding neighborhood income segregation around the clock using mobile phone ambient population data
Authors: Cai Liang , Song Guangwen , Zhang Yanji
Published: February 2024

This study examines the temporal changes in income segregation within the ambient population around the clock using mobile phone big data. It employs ordinal entropy, a metric suited for measuring segregation among ordered groups, to quantify the level of segregation among eight income groups within micro-geographic units throughout the 24-h period on a weekday and a weekend day in the urban core of Guangzhou, China. The study further decomposes daily segregation by location and time profile. We identify urban functions and neighborhood contexts relevant for income segregation and explore their temporal variation. Using group-based trajectory analysis, we classify daily segregation trends among 400 m urban grids into seven distinct trajectories for both weekday and weekend. Our findings confirm that segregation fluctuates constantly. The role of local urban functions, particularly retail, accommodation, and offices, and neighborhood context, such as the number of residents and the share of non-local migrants, exhibits a significant temporal rhythm. The seemingly convoluted 24-h segregation time series among urban grids follow just a few distinct trajectories with clear geographical patterns. There is limited variability at individual grids both over the course of a day and across days. Shifts across different trajectory types between weekday and weekend are rare. The dynamic daily segregation in the ambient population per se may be an enduring characteristic of neighborhoods and a real-time channel for neighborhood contextual influences, potentially fueling long-term residential segregation and neighborhood change.
Risk spillovers in Chinese production network: A supply-side shock perspective
Authors: Chi Yuxue , Jing Zhongbo , Liu Zhidong , Zhou Xinge
Published: February 2024

Highly interconnected production network exists in one economy, and it is crucial to investigate how and why supply-side shocks spread across industries via the production network and cause systemic risks in the real sector. Based on input-output framework, this paper designed a model to simulate the propagation of risk spillovers along the production network given supply-side shocks. This paper defined the systemically important industries (SIIs) and systemically vulnerable industries (SVIs) according to the degree and direction of risk spillovers. Simulation results show that risk spillovers spread among industries via the production network, leading to systemic risk in the real sector. This paper also classified the important risk spillover paths “SVIs → SIIs → SVIs” in the model for risk regulation and prevention and identified 75 risk spillover paths and 9 closed-loop paths in 2018. Furthermore, key factors of systemic importance (vulnerability) included input-output relationships and production network centrality. This paper provides a scientific basis to strengthen the risk supervision of the real sector based on the supply chain.
Design of soft x-ray varied-line-spacing (VLS) high-dispersion laminar-type grating coated with super-mirror-type (SMT) multilayer for flat-field spectrograph in a region of 2–4 keV
Authors: Koike M. , Hatano T. , Pirozhkov A. S. , Ueno Y. , Terauchi M.
Published: February 2024

A soft x-ray varied-line-spacing (VLS) laminar-type spherical grating with a super-mirror-type (SMT) multilayer was designed for a soft x-ray high resolution flat-field spectrograph in a region of 2–4 keV. The effective groove density of the designed VLS grating is 3200 lines/mm, and the local groove density varies from 2700 to 3866 lines/mm. The geometrical imaging property was evaluated by numerical calculations. The resolving power estimated by means of ray tracing was up to ∼103. For the evaluation of diffraction efficiency, the SMT multilayer structure designed for 3200 lines/mm in our previous work, Koike et al., Rev. Sci. Instrum. 94, 045109 (2023), was employed, and the numerical calculation was performed considering the local groove density of VLS grooves and the local incidence angle being affected by the curvature of the spherical surface and the geometrical relation between the source and incidence point on the grating. The results showed that the SMT multilayer-coated grating exhibited about an order of magnitude higher diffraction efficiency compared with an Au-coated grating.
Effect of temperature and magnetic field induced hysteresis on reversibility of magnetocaloric effect and its minimization by optimizing the geometrical compatibility condition in Mn–Ni–Fe–Si alloy
Authors: Panda Shantanu Kumar , Biswal Sambit Kumar , Dev Amar , Mallick Jyotirekha , Datta Subhadeep , Kar Manoranjan
Published: February 2024

The advancement of magnetic materials with coupled magneto-structural phase transition (MST) to fulfill the ultimate objectives of practical solid-state cooling applications requires a better understanding of the hysteresis phenomenon linked across the phase transition region along with the large magnetocaloric parameters. For the present sample Mn0.65Ni0.65Fe0.70Si, the MST is associated with a sharp jump in magnetization along with a small thermal hysteresis of ∼13 K. A giant isothermal magnetic entropy change (|ΔSMmax|) of ∼37.6 J kg−1 K−1 at 299 K and effective refrigerant capacity (RCeffe) of ∼214.3 J kg−1 under ΔH = 30 kOe is obtained with excellent compatibility between the martensite and austenite phases. The geometrical compatibility condition, i.e., very small (∼0.55%) deviation of the middle eigenvalue (λ2) from unity justifies the observation of small hysteresis in the present material. The investigation of hysteresis behavior under different extents of the driving forces (temperature or magnetic field) reveals that both the driving forces trigger equally the phase transition and are responsible equivalently for the hysteresis phenomenon. The present study provides a pathway to understand the complexity of the hysteresis behavior, its impact on the reversibility of magnetocaloric effect, and its minimization by optimizing the geometrical compatibility condition between the austenite and martensite phases.
Layer-by-layer assembly of nanotheranostic particles for simultaneous delivery of docetaxel and doxorubicin to target osteosarcoma
Authors: Desmond Liam , Margini Simone , Barchiesi Emilio , Pontrelli Giuseppe , Phan Anh N. , Gentile Piergiorgio
Published: February 2024

Osteosarcoma (OS) is a rare form of primary bone cancer, impacting approximately 3.4 × 106 individuals worldwide each year, primarily afflicting children. Given the limitations of existing cancer therapies, the emergence of nanotheranostic platforms has generated considerable research interest in recent decades. These platforms seamlessly integrate therapeutic potential of drug compounds with the diagnostic capabilities of imaging probes within a single construct. This innovation has opened avenues for enhanced drug delivery to targeted sites while concurrently enabling real-time monitoring of the vehicle's trajectory. In this study, we developed a nanotheranostic system employing the layer-by-layer (LbL) technique on a core containing doxorubicin (DOXO) and in-house synthesized carbon quantum dots. By utilizing chitosan and chondroitin sulfate as polyelectrolytes, we constructed a multilayered coating to encapsulate DOXO and docetaxel, achieving a coordinated co-delivery of both drugs. The LbL-functionalized nanoparticles exhibited an approximate size of 150 nm, manifesting a predominantly uniform and spherical morphology, with an encapsulation efficiency of 48% for both drugs. The presence of seven layers in these systems facilitated controlled drug release over time, as evidenced by in vitro release tests. Finally, the impact of the LbL-functionalized nanoparticles was evaluated on U2OS and Saos-2 osteosarcoma cells. The synergistic effect of the two drugs was found to be crucial in inducing cell death, particularly in Saos-2 cells treated with nanoparticles at concentrations higher than 10 μg/ml. Transmission electron microscopy analysis confirmed the internalization of the nanoparticles into both cell types through endocytic mechanisms, revealing an underlying mechanism of necrosis-induced cell death.
Measuring thermal profiles in high explosives using neural networks
Authors: Greenhall J. , Zerkle D. K. , Davis E. S. , Broilo R. , Pantea C.
Published: February 2024

We present a new method for calculating the temperature profile of high explosive (HE) material using a Convolutional Neural Network (CNN). To train/test the CNN, we have developed a hybrid experiment/simulation method for collecting acoustic and temperature data. We experimentally heat cylindrical containers of HE material until detonation/deflagration, where we continuously measure the acoustic bursts through the HE using multiple acoustic transducers lined around the exterior container circumference. However, measuring the temperature profile in the HE in an experiment would require inserting a large number of thermal probes, which would disrupt the heating process. Thus, we use two thermal probes, one at the HE center and one at the wall. We then use numerical simulation of the heating process to calculate the temperature distribution and correct the simulated temperatures based on the experimental center and wall temperatures. We calculate temperature errors on the order of 15 °C, which is ∼12% of the range of temperatures in the experiment. We also investigate how the algorithm’s accuracy is affected by the number of acoustic receivers used to collect each measurement and the resolution of the temperature prediction. This work provides a means of assessing the safety status of HE material, which cannot be achieved using existing temperature measurement methods. In addition, it has implications for a range of other applications where internal temperature profile measurements would provide critical information. These applications include detecting chemical reactions, observing thermodynamic processes such as combustion, monitoring metal or plastic casting, determining the energy density in thermal storage capsules, and identifying abnormal battery operations.
MPQA method applied to the plasma dispersion function
Authors: Morales-Campaña E. , Martin P.
Published: February 2024

A new approximation method for the plasma dispersion function Z(ζ) is presented. Multipoint quasi-rational approximation technique is used to find a bridge function that connects the power series and the asymptotic expansion of the function Z(ζ) using rational functions combined with exponential functions. An approximation with a polynomial of degree 10 is performed for the function Z(ζ), and the results obtained are compared with those of previous approximations from the literature. The results of this approximation were a relative error of ɛ = 0.0035 for Re[Z̃(ζ)] and a relative error of ɛ = 0.0011 for Im[Z̃(ζ)], which are lower than those of the other existing approximations.
Adaptive temporal transformer method for short-term wind power forecasting considering shift in time series distribution
Authors: Li Dan , Hu Yue , Miao Shuwei , Fang Zeren , Liang Yunyan , He Shuai
Published: February 2024

In wind power prediction, the input probability distributions in the different sub-periods are shifted owing to the strong randomness of the input features, such as wind speed and direction. This may violate the assumption for machine learning that the training and test data meet the condition of being independent and identically distributed, resulting in an insufficient generalization ability of the prediction model that is trained with the training data and applied to unknown test data. To address this problem, this study proposes an adaptive temporal transformer method for short-term wind power forecasting. First, a temporal transformer model with a gate recurrent unit and multi-head attention layers was used to extract the short- and long-term temporal information of the multiple input variables. Then, an adaptive learning strategy consisting of two stages—temporal distribution characterization and temporal distribution matching—was developed to explore the common knowledge hidden in each sub-period. The case results for an actual wind farm in northwest China showed that the proposed method could effectively weaken the adverse effects of the shifts in time series distribution on forecasting and improve the accuracy and generalization of short-term wind power prediction.
Aeroacoustic simulation of bluff bodies with protrusions at moderate Reynolds number
Authors: Kusano Kazuya
Published: February 2024

This paper presents an evaluation of passive control methods that employ surface protrusions to mitigate the aerodynamic sound generated from a cylinder wake flow. Building on previous designs optimized for low Reynolds numbers (Re = 150) through adjoint-based aeroacoustic shape optimization, this study investigated the performance under a moderate Reynolds number (Re = 67 000) condition typical of mechanical engineering applications using aeroacoustic simulations based on the lattice Boltzmann method. Three configurations of surface protrusions were tested, all of which were found to significantly reduce the mean drag by at least 45% compared with that of an unmodified circular cylinder. Designs featuring rear protrusions outperformed the conventional splitter plate in terms of the sound reduction performance, with symmetrical protrusions on both the front and rear surfaces achieving a tonal sound reduction of 13 dB. However, a specific protrusion design increased the low-frequency sound owing to the intensified large-scale flow separation. These findings highlight the effectiveness of rear protrusions in suppressing wake oscillations and dipole sound generation in the subcritical Reynolds number range. Moreover, the study revealed the need to tailor the front protrusion shape to the Reynolds number for performance optimization.
Sensitivity analysis of multipactor susceptibility zone to variations in secondary electron yield values
Authors: Mirmozafari M. , Behdad N. , Booske J. H.
Published: February 2024

We present a sensitivity analysis of the multipactor susceptibility zones to variations in the secondary electron yield (SEY) of materials, specifically focusing on the first and second unity crossover points of SEYs. In conducting this research, we leveraged our semi-analytic approach, which allows for the rapid prediction of the full multipactor zones with enhanced accuracy. Using this approach, we unveil several unique features of multipactor susceptibility zones, including the infinite extension of different-order multipactor zones and the overlap between them. Building upon this prediction capability, our results complement previous findings on the same topic and reveal that the multipactor zones depend not only on the first crossover point but also on the second crossover point of SEY, which this latter predominantly impacts multipactor susceptibility zones for low SEY materials. To validate our predictions, we present two distinct sets of multipactor experiments, providing empirical support for our results.
Coupled models for propagation of explosive shock waves in cylindrical and spherical geometries
Authors: Cao C. Y. , Sun Y. B. , Wang C. , Jia X. Y. , Zeng R. H. , Yang T. H.
Published: February 2024

The propagation of shock waves in different geometries is crucial in engineering and scientific applications. A comprehensive model is developed to elucidate the hydrodynamic growth and decay of shock waves in cylindrical and spherical geometries by using the strong shock wave assumption. This model takes into consideration the conservation equations governing mass, momentum, and energy, thereby allowing for an accurate description of the coupled behavior between the piston and shock wave propagation. In contrast to the localized analysis employed in previous self-similar methods, this model incorporates the finite sound wave velocity to introduce the concept of retarded pressure on the piston surface. Consequently, the proposed model offers a multitude of advantages by providing a complete set of dynamic information concerning the trajectories, velocities, and accelerations of both the piston and shock wave. Furthermore, an asymptotic analytical solution is derived to describe the decay of shock waves in cylindrical and spherical geometries. To validate the theoretical analysis and illustrate the propagation characteristics of shock waves in these specific geometries, thorough comparisons are conducted. These findings contribute to the advancement of our understanding of shock wave dynamics in various physical systems, particularly in the field of plasma physics.
Microscopic transmittance spectroscopy using a supercontinuum laser source
Authors: Chang Kuan-Yuan , Chang Wen-Tsan , Liu Jia-Ming
Published: February 2024

A supercontinuum laser source emitted from an optical fiber is suitable for developing microscopic transmittance spectroscopy. The microscopic supercontinuum transmittance spectrum can be taken with a fiber probe or a reflective objective. The reflective objective is only suitable for measuring a very thin sample of a thickness less than 1 µm. Therefore, while measuring a relatively thick sample, the fiber probe is the better choice because it effectively simplifies the system without lowering the resolution. The spatial resolution of the microscopic transmittance spectrum as a function of the optical wavelength, measurement distance, and sample thickness is quantitatively evaluated for a fiber probe.
Nonmonotonic polymer translocation kinetics through nanopores under changing surface–polymer interactions
Authors: Manohar Neha , Riggleman Robert A. , Lee Daeyeon , Stebe Kathleen J.
Published: February 2024

Understanding the dynamics of polymers in confined environments is pivotal for diverse applications ranging from polymer upcycling to bioseparations. In this study, we develop an entropic barrier model using self-consistent field theory that considers the effect of attractive surface interactions, solvation, and confinement on polymer kinetics. In this model, we consider the translocation of a polymer from one cavity into a second cavity through a single-segment-width nanopore. We find that, for a polymer in a good solvent (i.e., excluded volume, u0 > 0), there is a nonmonotonic dependence of mean translocation time (τ) on surface interaction strength, ɛ. At low ɛ, excluded volume interactions lead to an energetic penalty and longer translocation times. As ɛ increases, the surface interactions counteract the energetic penalty imposed by excluded volume and the polymer translocates faster through the nanopore. However, as ɛ continues to increase, an adsorption transition occurs, which leads to significantly slower kinetics due to the penalty of desorption from the first cavity. The ɛ at which this adsorption transition occurs is a function of the excluded volume, with higher u0 leading to an adsorption transition at higher ɛ. Finally, we consider the effect of translocation across different size cavities. We find that the kinetics for translocation into a smaller cavity speeds up while translocation to a larger cavity slows down with increasing ɛ due to higher surface contact under stronger confinement.
Fractional Extended Diffusion Theory to capture anomalous relaxation from biased/accelerated molecular simulations
Authors: Rapallo Arnaldo
Published: February 2024

Biased and accelerated molecular simulations (BAMS) are widely used tools to observe relevant molecular phenomena occurring on time scales inaccessible to standard molecular dynamics, but evaluation of the physical time scales involved in the processes is not directly possible from them. For this reason, the problem of recovering dynamics from such kinds of simulations is the object of very active research due to the relevant theoretical and practical implications of dynamics on the properties of both natural and synthetic molecular systems. In a recent paper [A. Rapallo et al., J. Comput. Chem. 42, 586–599 (2021)], it has been shown how the coupling of BAMS (which destroys the dynamics but allows to calculate average properties) with Extended Diffusion Theory (EDT) (which requires input appropriate equilibrium averages calculated over the BAMS trajectories) allows to effectively use the Smoluchowski equation to calculate the orientational time correlation function of the head–tail unit vector defined over a peptide in water solution. Orientational relaxation of this vector is the result of the coupling of internal molecular motions with overall molecular rotation, and it was very well described by correlation functions expressed in terms of weighted sums of suitable time-exponentially decaying functions, in agreement with a Brownian diffusive regime. However, situations occur where exponentially decaying functions are no longer appropriate to capture the actual dynamical behavior, which exhibits persistent long time correlations, compatible with the so called subdiffusive regimes. In this paper, a generalization of EDT will be given, exploiting a fractional Smoluchowski equation (FEDT) to capture the non-exponential character observed in the relaxation of intramolecular distances and molecular radius of gyration, whose dynamics depend on internal molecular motions only. The calculation methods, proper to EDT, are adapted to implement the generalization of the theory, and the resulting algorithm confirms FEDT as a tool of practical value in recovering dynamics from BAMS, to be used in general situations, involving both regular and anomalous diffusion regimes.
Y3Fe5O12 film with multi-domain epitaxy on single-crystalline LiNbO3 substrate
Authors: Yamanoi Kazuto , Hase Kenta , Komori Sachio , Taniyama Tomoyasu , Nozaki Yukio
Published: February 2024

Y3Fe5O12 is one of the magnetic insulators that can realize high-speed and low-power-consuming spintronics devices. However, it is hard to prepare a high-quality Y3Fe5O12 film via a conventional sputtering process owing to its low crystalline texture, which leads to a crucial increase in the Gilbert damping constant. Moreover, a single crystalline Gd3Ga5O12 substrate, whose lattice constant is well matched with Y3Fe5O12, is indispensable to improve the crystallinity of the Y3Fe5O12 film. In this article, we demonstrated an epitaxial growth of multiple domains for a 30-nm-thick Y3Fe5O12 film by means of magnetron sputtering on a single crystalline 128° Y–X LiNbO3 substrate , which has been widely utilized in surface acoustic wave devices. From the pole figure of x-ray diffraction, an oblique epitaxial growth of Y3Fe5O12(400) is successfully observed on the 128° Y–X LiNbO3 substrate after a high-temperature post-annealing. The saturation magnetization is equivalent to the value of the epitaxial Y3Fe5O12 film on the Gd3Ga5O12 substrate. The relatively low effective Gilbert damping constant of 0.0039 also supports the high crystalline texture of the Y3Fe5O12 film. The developed growth technique will pave the way for the application of the Y3Fe5O12 film on magneto-acoustic devices.
A novel method for supersonic plasma measurement using a double-jacketed enthalpy probe
Authors: Seo Jun-Ho , Kim Dong-Uk , Nam Jun-Seok , Yang In-Mok , Choi Min-Gyu
Published: February 2024

A novel method to characterize a supersonic plasma jet using a double-jacketed enthalpy probe is presented and applied to Ar supersonic plasma jets generated by a plasma torch operated at an input power level of 5.7 kW and a chamber pressure of 2.3 kPa. The basis of this method is to measure total stagnation pressure, total enthalpy, and static pressure at the backside of a shock wave formed in front of the probe with a single insertion of the probe. Once these three variables are known, normal shock relations before and after the shock wave can disclose information on static pressures, Mach numbers, temperatures, and velocities of the supersonic plasma jet under a calorically perfect gas assumption. For example, measurement experiments carried out with the proposed probe revealed that static pressure of Ar supersonic plasma jet oscillated around the chamber pressure of 2.3 kPa in a range of 1–5 kPa along the jet axis, clearly showing an aerodynamic non-equilibrium. Corresponding to the behaviors of static pressures, Mach numbers also oscillated in the range of 1.1–3.5 along the jet axis. In addition, oscillation patterns of static pressures and Mach numbers agreed well with those of compression and expansion wave zones observed in the photograph of an over-expanded Ar supersonic plasma jet. Although relatively large errors were accompanied due to a low input power level, plasma temperatures and velocities were measured to be decreasing and increasing, respectively, in the expansion wave zone while opposite behaviors were observed in the compression wave zone.
Strain tuned structural, mechanical, electronic, and optical properties of lead-free oxy-nitride SrTaO2N perovskite using first-principles study
Authors: Khatamunnaby Golam Md. , Hasan Khan Md. Sakib , Hasan Md. Tanvir , Islam Md. Rafiqul , Rahman Muhammed Zubair
Published: February 2024

Recent advancements in perovskite-based solar energy conversion technologies require materials having enhanced optoelectronic properties and stability. Harnessing density functional theory (DFT), we have investigated here a novel orthorhombic phase of a recently synthesized oxynitride perovskite, SrTaO2N, and its uniaxial strain-tunable electronic and optical properties. Phonon dispersion and formation energy calculations are utilized to determine lattice dynamic stability and exothermic formation feasibility of the structure, correspondingly. The predicted bandgap at the Heyd–Scuseria–Ernzerhof [generalized gradient approximation Perdew–Burke–Ernzerhof (GGA-PBE)] level is ∼2.125 eV (∼1.125 eV), which is highly receptive to uniaxial strains. The bandgap formed in between X and G points with high symmetry at the first Brillouin zone was further dissected using the atomic orbital projected density of states (PDOS). The PDOS showed that the N-pz orbital dominantly contributes to valence band maxima and the Ta-dz2 orbital to conduction band minima. Compressive uniaxial strain widens the bandgap by ∼1.21 times, while tensile uniaxial strain lowers the bandgap by ∼1.1 times from the intrinsic value, suggesting strain switchable bandgap nature in the material. An elastic constant matrix also evaluates the mechanical stability of strained structures, and we found that in the strained structures from −6% to +6%, SrTaO2N is mechanically stable and ductile. Optical absorption reveals an increased absorption coefficient in the visible spectrum. These strain-tuned optoelectronic properties through the DFT approach thus suggest an evident route to a wide range of optoelectronics applications of the SrTaO2N perovskite material.
Post-trench restoration for vertical GaN power devices
Authors: Li Yanjun , Ren Na , Wang Hengyu , Guo Qing , Wang Ce , Cheng Haoyuan , Wan Jiangbin , Li Junze , Sheng Kuang
Published: February 2024

The impact of the post-trench restoration on the electrical characteristics of vertical GaN power devices is systematically investigated in this work. Following the achievement of microtrench-free GaN trench structure with modified dry etching conditions, the post-trench tetramethylammonium hydroxide (TMAH)-based wet etching and UV/Ozone-based oxidation process are employed to further refine the trench profile. It is shown that the c-plane trench bottom is restored to the level of unetched surface, as evidenced by the improved Schottky interface. Additionally, the post-trench treatment exhibits the anisotropic characteristics with the preferred rounded corner profile on m-plane sidewall compared to a-plane sidewall. The simulations and experimental results demonstrate that the trench MOS barrier Schottky (TMBS) rectifier based on m-plane sidewall could suppress the electric field crowding at the trench corner and, hence, reduce the reverse leakage current by 1–2 orders of magnitude. Furthermore, the MOSCAP test structures were fabricated on the trenches. The extracted interface trap density (Dit) confirms the effective restoration of trench bottom. However, the sidewall surface exhibits the relatively large Dit, which emphasizes the necessity of optimizing the sidewall, particularly for devices incorporating sidewall channel. The demonstrated post-trench restoration technique improves the surface quality and trench structure for the significantly enhanced electrical performances, which is essential for the development of vertical GaN power devices.