bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy harvesting using a dynamic weighing system based on piezoelectric materials
Authors: Fangachi Najoua , Najihi Ikrame , Yessari Madiha , Hajjaji Abdelowahed
Published: September 2022

Road transport is one of the main energy-consuming sectors. Therefore, the concept discussed in this article is of great interest since it aims to transform this sector into a producer of clean and renewable energy by using piezoelectric conversion. The work carried out in this article concerns the study of the electrical power density recovered by a miniaturized dynamic weighing system using piezoelectric sensors inserted into the road surface and by varying the speed and the weight of the vehicle. The system studied in this article therefore offers the possibility of measuring and then controlling the load of a moving vehicle using the vibrations generated during its passage and then converting them into electricity by direct piezoelectric effect. A mathematical model representing the relationship between the weight of the vehicle and the voltage peaks generated by the passage of the latter over the piezoelectric sensors has been developed. This model was implemented on the Matlab software, which made it possible to carry out, based on several experimental tests, a study of the variation of the coefficients of proportionality according to the weight of the vehicle and its rolling speed. The power density collected by this application at different speeds and masses was then calculated. According to the tests carried out, the recovered power density is approximately 36.06 W/m3for a travel speed of 0.52 m/s and a vehicle weight equal to 1150 g.
Simulating hydrogen embrittlement fracture based on phase field method
Authors: CHEN Pengcheng , MA Yu'e , PENG Fan , ZHOU Linglong
Published: September 2022

The phase field hydrogen embrittlement fracture model is improved by introducing tension-compression split of strain energy. The numerical formulas of the model are provided, besides, the coupling term of concentration field and displacement field is deduced. The matlab software is used to compile the numerical program of phase field hydrogen embrittlement fracture. The modes I and II cracks of hydrogen embrittlement are simulated respectively. The simulation results show that hydrogen ions concentrate at the crack tip where stress concentration happens, and that the hydrogen concentration reduces the critical failure load of the square plate. Compared with the numerical results of the existing models, the improved model can accurately calculate the critical failure load in the mode I crack and capture the embrittlement fracture phenomenon when the phase field and the concentration field are accumulated near the crack tip. Moreover, the improved model can effectively simulate the mode II crack with hydrogen embrittlement.
Study on design of low Reynolds number reflexed airfoil for solar-powered UAV in flying wing configuration
Authors: WANG Kelei , ZHOU Zhou , GUO Jiahao , XU De
Published: September 2022

Based on the application requirements of a small hand-launched solar-powered unmanned aerial vehicle (UAV) in flying wing configuration, the optimization design of the low Reynolds number (LRN) reflexed airfoil is carried out in this study to meet several requirements such as high lift, mild stall, demanding pitching moment. Firstly, the accuracy and reliability of both quasi-steady and unsteady numerical methods to simulate the LRN transition flow and the stall separated flow at large angles of attack (AOA) are validated by an airfoil case study at specified Reynolds numbers; Secondly, the LRN reflexed air-foil optimization design framework is established by using the CST parameterization method, the multi-island genetic algorithm (MIGA), and the kriging surrogate model; Lastly, the LRN reflexed airfoil optimization study is conducted by using the NACA 8-H-12 reflexed airfoil as the baseline airfoil, it shows that both the lift-to-drag performance and the stall characteristics of the designed airfoil is significantly improved when compared with the baseline airfoil, which are quite beneficial for the small hand-launched solar-powered UAV in flying wing configuration to realize the hand-launched take off and the high-lift long-endurance flight.
Predicting trajectory of drogue based on multi-head convolutional long-short-term memory network
Authors: WU Cihang , YAN Jianguo , CHENG Long , WANG Jiawei , GUO Yiming , XING Xiaojun
Published: September 2022

Aerial refueling is an important technology of great military significance. It can effectively boost an aircraft's performance owing to the longer period of time and longer endurance of range an aircraft can maintain in the air. To solve the problem that it is hard for a receiver aircraft to track a drogue during its docking phase, a drogue trajectory prediction method based on the multi-head convolutional long-short-term memory network is proposed. First, the one-dimensional time sequence data of the drogue is extended to its high-dimensional space. Then its spatial features are extracted through the multi-head convolutional residual network and fused together. On this basis, a long-short-term memory network is adopted to reveal the underlying temporal correlations among the spatial features and predict the trajectory of the drogue. The simulation and experimental results show that the method presented in this paper has a higher prediction accuracy than the traditional prediction methods that use time sequence data.
GPS spoofing detection algorithm for quad-rotor helicopter based on speed/height comparison
Authors: GU Zhaojun , CHEN Hui , WANG Jialiang , CUI Haibin
Published: September 2022

In order to detect whether the GPS is abnormal in the flight state of small size quad-rotor, a GPS spoofing detection algorithm based on data fusion is proposed. Firstly, the velocity data from the monocular camera is calculated by using the self-velocity measurement algorithm based on the improved pyramid optical flow method. Secondly, the speed and altitude data of the IMU sensor unit of the small size quad-rotor were obtained, exactly the speed data were fused with the velocity data measured by using the optical flow method to obtain the optimal velocity estimation at that time. Finally, the small size quad-rotor GPS sensor data information is obtained, the aircraft speed and altitude data are calculated, and comparing with the data calculated in the previous step, to determine whether the GPS data at this time is abnormal. The experimental results on Anafi show that the present GPS spoofing detection algorithm can quickly detect data anomalies during flight. It can be seen that the present algorithm can provide strong technical support for GPS spoofing detection of quad-rotor.
Optimal investment and reinsurance on survival and growth problems for the risk model with common shock dependence
Authors: Duan Shida , Liang Zhibin
Published: September 2022

This paper investigates goal-reaching problems regarding optimal investment and proportional reinsurance with two dependent classes of insurance business, where the two claim number processes are correlated through a common shock component. The optimization problems are formulated in a general form first, and then four criteria including maximum survival probability, minimum expected ruin penalty, minimum (maximum) expected time (reward) to reach a goal are fully discussed. By the technique of stochastic control theory and through the corresponding Hamilton–Jacobi–Bellman equation, the optimal results are derived and analyzed in different cases. In particular, when discussing the maximum survival probability with a target level U beyond the safe level (where ruin can be avoided with certainty once it is achieved), we construct ε-optimal (suboptimal) strategies to resolve the inaccessibility of the safe level caused by classical optimal strategies. Furthermore, numerical simulations and analysis are presented to illustrate the influence of typical parameters on the main results.
Ganzheitlich unter-suchen und behandeln – Clinical Reasoning – Teil 1 von 3
Authors: Jones Mark
Published: September 2022

Im Clinical-Reasoning-Prozess sollen Therapeut*innen peu à peu ein Verständnis für das klinische Bild eines Menschen, für seine Person und die jeweiligen Umwelteinflüsse entwickeln. Die komplexen Denk- und Entscheidungsprozesse erfordern fundiertes Fachwissen, analytisches Denken, Soft Skills und nicht zuletzt Selbstreflexion. Expert*innen nutzen die klinische Mustererkennung und stellen schnell die richtige Diagnose.
Distanz vor Intensität – Return to Running postnatal
Authors: Reich Sonja , Kranz Magdalena
Published: September 2022

Return to Activity (RTA) ist in aller Munde. Doch nicht nur für Athlet*innen, auch für laufbegeisterte Mütter ist es wichtig zu wissen, wann sie wieder mit dem Training beginnen können. Physiotherapeut*innen können dabei helfen, diese Frage zu beantworten, und passgenaue Übungen anbieten.
Reden Physios mit? – Förderung neuer Versorgungsmodelle
Authors: Aschoff Frank
Published: September 2022

Alle rund 73 Millionen gesetzlich Kranken-versicherten haben in Deutschland Anspruch auf eine „ausreichende, zweckmäßige und wirtschaftliche Gesundheitsversorgung“. Über Förderung und Einführung neuer Versorgungsformen, auch in der Physiotherapie, entscheidet der Gemeinsame Bundesausschuss.
Reduced 5-Year Risk for Revision of the Oxford UKA Using New Instrumentation versus Conventional Instrumentation: A Registry Study of 12,867 UKAs
Authors: van Langeveld Stephan J. , Janssen Stein J. , Koenraadt Koen L. M. , Elmans Leon H. G. J. , van Steenbergen Liza N. , van Geenen Rutger C. I.
Published: September 2022

Microplasty instrumentation was introduced for a more consistent surgical implantation technique, especially component alignment and tibial resection level, of the Oxford medial unicompartmental knee arthroplasty (UKA) and thereby aims to improve UKA survival. This study aimed to assess the 5-year risk for revision and reasons for revision of the Oxford medial UKA using the new instrumentation (Microplasty) with its predecessor, that is, conventional instrumentation (Phase 3). Data of all medial UKAs from the Dutch Arthroplasty Register (Landelijke Registratie Orthopedische Implantaten) between 2007 and 2019 were collected. Type of instrumentation was divided into new (Microplasty) and conventional instrumentation. Kaplan–Meier analysis was performed to calculate 5-year cumulative revision percentage with any reason for revision as end point. A multivariable Cox regression with outcome revision of UKA adjusted for age, gender, American Society of Anesthesiologists score, surgical history, and type of fixation was performed. Additionally, reasons for revision at 3-year were assessed and tested through Fisher's exact tests. A total of 12,867 Oxford medial UKAs, 8,170 using new and 4,697 using conventional instrumentation, were included. The 5-year revision percentage was 9.2% (95% confidence interval [CI]: 8.4–10.1%) for UKAs using the conventional and 6.1% (95% CI: 5.4–6.7%) for new instrumentation. The adjusted hazard ratio for revision at 5-year follow-up was 0.74 (95% CI: 0.63–0.87) in favor of UKAs using the new instrumentation. Malalignment was more frequently registered as reason for revision in UKAs using the conventional compared with the new instrumentation (16% versus 7.5%; p = 0.001). Our results show a reduced 5-year risk for revision of the medial Oxford UKAs using the new compared with the conventional instrumentation. This might be the result of a lower revision rate for malalignment in UKAs using the new instrumentation.
Mid-Term Clinical and Radiological Outcomes of Lateral Meniscal Allograft Transplantation with Suture-Only Fixation Plus Capsulodesis
Authors: Morales-Avalos Rodolfo , Masferrer-Pino Ángel , Padilla-Medina José Ramón , Amestoy-Ramos Jorge , Ibáñez Maximiliano , Perelli Simone , Ariztegui-Andrade Cristina , Espregueira-Mendes João , Monllau Joan Carles
Published: September 2022

Meniscal allograft transplantation (MAT) is an effective reconstructive procedure for treating a symptomatic postmeniscectomy syndrome. It consists of replacing the lost meniscal tissue aiming to improve the clinical outcomes and prevent progressive deterioration of the joint. The aim of this study was to evaluate meniscal graft survivorship and report on the radiographic (in terms of graft extrusion and joint space width and alignment) and the functional results through a midterm follow-up of lateral MAT performed with a soft tissue fixation technique after capsulodesis. In total, 23 patients who underwent lateral MAT as a single procedure were included. The Knee injury and Osteoarthritis Outcome Score, Lysholm, Tegner, and visual analog scale scales were used for patient assessment. Magnetic resonance imaging and a complete radiographic protocol were conducted to determine the degree of meniscal extrusion and the changes in the degree of osteoarthritis and coronal alignment. Assessments were performed after 2 and 7 years of follow-up. A significant improvement in all the scores, relative to preoperative values, was found after 7 years of follow-up. This improvement remained consistent throughout the first and second follow-up periods. A mean absolute extrusion of 2.2 mm ± 1.6 and an extrusion percentage of 28.0% ± 11.43 were found, with no significant differences throughout the follow-up periods. There was no statistically significant difference in terms of the frontal mechanical axis and joint space narrowing between the preoperative value and at the first and second follow-up periods. A survival rate of 85.7% was found after 7 years of follow-up. Capsulodesis results in a low degree of meniscal extrusion in isolated lateral MAT fixed with a suture-only technique, which is maintained after 7 years of follow-up, with a high graft survival index (>85%) and satisfactory results on the functional scales.
Photocatalytic Decarboxylative Cyclization of 1,6-Enynes and N-Methacryloyl-2-phenylbenzimidazoles by Potassium Iodide/ Triphenylphosphine Catalysis
Authors: Ge Guo-Ping , Liu Hongxin , Wei Wen-Ting , Zhang Jian , Li Jiao-Zhe , Wang Ling-Tao , Yu Xuan-Chi , Zhang Jun-Hao
Published: September 2022

We describe a photocatalytic decarboxylative cyclization of 1,6-enynes or N-methacryloyl-2-phenylbenzimidazoles for efficient and ecofriendly syntheses of lactams or benzimidazo[2,1-a]isoquinoline-6(5H)-ones, respectively, by the use of KI/PPh3 as a redox catalyst system. In this method, N-hydroxyphthalimide esters were used as alkyl-radical precursors to achieve this decarboxylative cyclization without any dyes, transition-metal catalysts, oxidants, or bases.
Diagnostic Testing for von Willebrand Disease: Trends and Insights from North American Laboratories over the Last Decade
Authors: Ziemba Yonah C. , Abdulrehman Jameel , Hollestelle Martine J. , Meijer Piet , Plumhoff Elizabeth , Hsu Peihong , Selby Rita
Published: September 2022

Accurate diagnosis of von Willebrand disease (VWD) depends on the quality, precision, and variability of the laboratory assays. The North American Specialized Coagulation Laboratory Association (NASCOLA) is a provider of external quality assessment (EQA) for approximately 60 specialized coagulation laboratories in North America. In this report, NASCOLA EQA data from 2010 to 2021 are reviewed for trends in methodology and precision among various assays. In particular, recent ASH ISTH NHF WFH (American Society of Hematology, International Society on Thrombosis and Haemostasis, National Hemophilia Foundation, and World Hemophilia Federation) guidelines for diagnosis of VWD are reviewed in light of EQA data. In contrast to other geographic regions, laboratories in North America predominantly use three-assay screening panels (antigen, platelet-binding activity, and factor VIII [FVIII] activity) rather than four-assay panels (antigen, platelet-binding activity, FVIII activity, and collagen-binding activity). They also use latex immunoassays rather than chemiluminescence immunoassays, and the classic ristocetin cofactor (VWF:RCo) assay and monoclonal antibody (VWF:Ab) assay to assess VWF platelet-binding activity over newer recommended assays (VWF:GPIbM and VWF:GPIbR). Factors that may be influencing these North American practice patterns include lack of Food and Drug Administration approval of the VWF:GPIbM, VWF:GPIbR, collagen binding assays, and chemiluminescence methodologies, and the influence of the 2008 National Heart, Lung, and Blood Institute guidelines on laboratory practice. Lastly, systems-based solutions are urgently needed to improve the overall accuracy of laboratory testing for VWD by minimizing preanalytical variables and adopting assay standardization.
Indian College of Radiology and Imaging Guidelines on Interventions in Hepatocellular Carcinoma
Authors: Gupta Pankaj , Kalra Naveen , Chaluvashetty Sreedhara B. , Gamangatti Shivanand , Mukund Amar , Abdul Razik , Shyam VS , Baijal Sanjay Saran , Mohan Chander
Published: September 2022

Hepatocellular carcinoma (HCC) is one of the most common malignancies and a significant cause of cancer-related death. Treatment of HCC depends on the stage of the tumor. As many patients with HCC are not deemed fit for surgical resection or liver transplantation, locoregional therapies play an essential role in the management. Image-guided locoregional treatments include percutaneous ablative therapies and endovascular therapies. The choice of an individual or a combination of therapies is guided by the tumor and patient characteristics. As the outcomes of image-guided locoregional treatments depend on the ability to achieve necrosis of the entire tumor along with a safety margin around it, it is mandatory to follow standard guidelines. In this manuscript, we discuss in detail the various aspects of image-guided locoregional therapies to guide interventional radiologists involved in the care of patients with HCC.
Medial Plica Syndrome of the Knee: Arthroscopic Plica Resection versus Structured Physiotherapy—A Randomized Controlled Trial
Authors: Sauer Steffen , Karlsen Gitte , Miller Lene , Storm Jens Ole
Published: September 2022

Background Medial plica syndrome is a commonly overlooked cause of anterior knee pain. A consensus on diagnosis and treatment is yet to be found. This study compares the clinical outcome of arthroscopic plica resection with structured physiotherapy for patients with isolated medial plica syndrome in a prospective randomized controlled trial with a 2-year follow-up.

Methods Forty-eight patients have been included in this prospective randomized controlled trial presenting medial plica syndrome. Patients were randomly assigned to either arthroscopic plica resection or structured physiotherapy. The primary outcome was the change in the average score of the Lysholm knee scoring scale from baseline to 2-year follow-up.

Results Mean baseline Lysholm score for patients assigned to arthroscopic plica resection and physiotherapy was 65.8 and 66.3, respectively. No significant difference was seen between the two groups. Thirty-three patients were assessed at 2 years follow up. The mean Lysholm score was 89.7 for patients assigned to arthroscopic plica resection and 74.6 for patients assigned to structured physiotherapy. A statistically significant difference was seen between the two groups (p = 0.007).

Conclusions Arthroscopic plica resection was associated with significantly greater clinical improvement compared with physiotherapy at 2-year follow-up.
Clinical Significance of Terminal Syringomyelia and Accompanying Congenital Anomalies of Neurosurgical Interest in Adult and Pediatric Patients with Tethered Cord Syndrome
Authors: Rakip Usame , Canbek İhsan , Yıldızhan Serhat , Boyacı Mehmet G. , Cengiz Akın , Aslan Adem
Published: September 2022

Magnetic resonance imaging (MRI) can be used to examine tethered cord syndrome (TCS) and terminal syringomyelia (TS). Additionally, there is increasing evidence of an association between congenital anomalies and TCS. We aimed to identify the clinical and radiological characteristics of syringomyelia and other anomalies in pediatric and adult patients with TCS. This study included 54 TCS patients (mean age, 17.37 ± 15.83 years; 31 females) admitted to our department between 2010 and 2019. The patients were divided into two age groups: pediatric (<18 years; 63%) and adult (>18 years). Clinical findings, direct vertebrae radiographs, lower extremity radiographs, and spinal/cranial MRI findings were used to evaluate all patients. Computed tomography (CT) was performed to reveal the structure of the septum in patients with Diastematomyelia. Cranial ultrasonography or CT was performed if the fontanel was open or closed, respectively, in pediatric hydrocephalus cases. Pelvic ultrasonography and urodynamic tests were performed to evaluate other comorbid anomalies and urinary system pathologies. A thick filum terminale (73.3%) and diastematomyelia (44.4%) were found to cause spinal tension. The most common accompanying pathology was syringomyelia (78%). The common symptoms were urinary incontinence and bowel problems (71%), scoliosis (68%), and progressive lower extremity weakness (64.4%). It is difficult to distinguish the exact cause of symptoms in patients with TCS and TS. Due to the greater occurrence of other congenital spinal anomalies accompanying TCS, both preoperative symptoms and clinical findings are more severe in the pediatric group than in the adult group, and postoperative results may be more negative.
5.2.7 Product Subclass 7: Stannylenes
Authors: Takeda N.
Published: September 2022

This is a revised Science of Synthesis contribution describing methods for the synthesis of stannylenes. Substitution reactions of stable tin(II) compounds such as SnCl2, chlorostannylenes, and aminostannylenes with organolithiums are useful synthetic methods for preparing stannylenes. Insertion reactions of multiple bonds into Sn–X (X = H, B, C, Sn) bonds of hydrostannylene dimers, borylstannylenes, or distannynes can also afford the corresponding stannylenes. In addition, migration reactions of hydrogen, carbon, and amino substituents in (dihydrostannyl)germylene and tin–metal double-bond compounds are used for the synthesis of metal-substituted stannylenes. Finally, reduction of tetravalent tin compounds, such as dibromostannanes, has also been reported for the synthesis of stannylenes.
Flexible ferroelectric Pb(Zr0.53Ti0.47)O3 epitaxial films with large radiation and high-temperature tolerance
Authors: Liu Yajing , Song Sijia , Gong Pin , Xu Longjie , Li Kaifeng , Li Dong , Wang Hongguang , Fan Jiyu , Qiu Lei , Tang Xiaobin , Li Weiwei , Yang Hao
Published: September 2022

Radiation and temperature hardness are important for electronic devices operating in harsh environments such as modern medical equipment, outer space, and nuclear energy industries. In this work, we report radiation and temperature-hardened flexible ferroelectric Pb(Zr0.53Ti0.47)O3 epitaxial films that were grown on flexible inorganic mica substrates via van der Waals heteroepitaxy and can be further used for building high-performance electronic devices. We systematically investigated the effect of 60Co-gamma radiation and temperature on the ferroelectric properties of Pb(Zr0.53Ti0.47)O3 films and their flexibility as well. Pb(Zr0.53Ti0.47)O3 films exhibit a radiation and temperature tolerance of up to 20 Mrad and 175 °C, respectively. In particular, the 20 Mrad-irradiated Pb(Zr0.53Ti0.47)O3 film has an excellent retention even after 105 s with extrapolate retention time longer than 10 years and polarization fatigue up to 1010 cycles as well as moderate flexibility and bending stability after bending 105 cycles. Furthermore, we identified that the degradation of macroscopic ferroelectric properties of irradiated Pb(Zr0.53Ti0.47)O3 films originates from the ferroelectric domain pinning effect induced by the ionization effect. Our work demonstrates that flexible ferroelectric Pb(Zr0.53Ti0.47)O3 films are promising for developing novel flexible electronic devices for applications in harsh environments.
Molecular beam epitaxy of highly crystalline GeSnC using CBr4 at low temperatures
Authors: Dey Tuhin , Reza Md. Shamim , Arbogast Augustus , Holtz Mark W. , Droopad Ravi , Bank Seth R. , Wistey Mark A.
Published: September 2022

Tensile-strained pseudomorphic Ge1–x–ySnxCy was grown on GaAs substrates by molecular beam epitaxy using carbon tetrabromide (CBr4) at low temperatures (171–258 °C). High resolution x-ray diffraction reveals good crystallinity in all samples. Atomic force microscopy showed atomically smooth surfaces with a maximum roughness of 1.9 nm. The presence of the 530.5 cm−1 local vibrational mode of carbon in the Raman spectrum verifies substitutional C incorporation in Ge1–x–ySnxCy samples. X-ray photoelectron spectroscopy confirms carbon bonding with Sn and Ge without evidence of sp2 or sp3 carbon formation. The commonly observed Raman features corresponding to alternative carbon phases were not detected. Furthermore, no Sn droplets were visible in scanning electron microscopy, illustrating the synergy in C and Sn incorporation and the potential of Ge1–x–ySnxCy active regions for silicon-based lasers.
Vacancy-induced heterogeneity for regulating thermoelectrics in n-type PbTe
Authors: Zhong Yan , Zhao Xuanwei , Deng Qian , An Xiang , Yuan Wei , Lv Fangling , Gan Lin , Ang Ran
Published: September 2022

The fact that the thermoelectric performance is far inferior to that of p-type PbTe has inspired many strategies to develop n-type PbTe thermoelectrics. Alloying PbS in n-type PbTe effectively changes the shape of a valley to trigger a heavier conduction band for improving the Seebeck coefficient, while the resulting small orbital overlap inevitably leads to phase separation hindering electron transport. The effect of vacancies on the solubility of sulfur in n-type PbTe is ambiguous; especially, the heterostructure due to phase separation in high-content PbS-alloyed PbTe also requires sufficient modification to optimize the electroacoustic transport. This motivates the current work on the introduction of vacancies by charge-balancing doping via Sb2Te3 and discovers striking new insight that the introduced vacancies can induce a new heterostructure of Pb2Sb2S5 and suppress the aggregation of Sb and PbS in high-solubility n-type PbTe–PbS. The modification of the band structure and optimization of the electron transport give rise to a prominent enhancement in electronic performance. Furthermore, the Debye–Callaway model validates the dramatic contribution of vacancy aggregation and heterostructures to lattice thermal conductivity. As a result, the synergistic modulation of electroacoustic characteristics achieves a significant improvement in both the maximum zT and the near-room-temperature zT. Understanding such unique findings is critical for applicability to other thermoelectric materials.
Droplet impact on hot substrates under a uniform electric field
Authors: Xu Haojie , Wang Junfeng , Yu Kai , Li Bin , Zhang Wei , Zuo Lei , Kim Hyoung-Bum
Published: September 2022

Droplet impact on a hot substrate under an electric field is fundamental and crucial for electrospray cooling. However, the involved thermal–electric coupling impact electrohydrodynamic has not been well understood. In this study, the effects of an electric field on the droplet impact behavior in different thermal regimes and the subsequent dynamic mechanisms were experimentally investigated. The results showed that the vertical electric field would result in an upward liquid ejection in the film evaporation regime. In the nucleate boiling regime, the liquid pinch-off phenomenon was observed. In addition, the droplet evaporation rate was increased by approximately 23% with an electric field of 6 kV/cm. In the film boiling regime, both the residence time and bounce-off droplet height were significantly increased. The various impact phenomena were mainly explained by the competition between electrostatic and capillary pressures. The comprehensive effects of surface free charges and temperature variation on the droplet surface tension coefficient were discussed. Moreover, according to the thermal analysis, the heat transfer in the film boiling regime with an electric field was enhanced by approximately 137%. This work contributed to the development of the droplet impact dynamics under the coupling temperature and electric fields and demonstrated great promise for the electric field for thermal-fluid manipulation.
Piezoelectric properties of (Na, K)(Nb, Sb)O3–CaZrO3 thin film grown on Sr2Nb3O10 perovskite oxide nanosheet at low temperatures
Authors: Shin Ho-Sung , Kim In-Su , Woo Jong-Un , Chae Seok-June , Kim Bumjoo , Nahm Sahn
Published: September 2022

A Sr2Nb3O10 (SNO) nanosheet was deposited on a Pt/Ti/SiO2/Si (Pt–Si) substrate using the Langmuir–Blodgett technique. An SNO monolayer was used as the seed layer for the growth of a crystalline 0.97(Na0.5K0.5)(Nb0.91Sb0.09)O3–0.03CaZrO3 (NKNS–CZ) thin film at a low temperature of 400 °C. The NKNS–CZ thin film grew along the [001] direction, and it had a dense microstructure with an average grain size of 75 nm. The dielectric constant of the film was 250, with a low dielectric loss of 3.5% at 100 kHz. The leakage current density of the Pt/NKNS–CZ top-electrode interface was approximately 1.3 × 10−6 A/cm2 at 0.05 MV/cm. Additionally, a slightly increased leakage density (8.1 × 10−5 A/cm2 at 0.05 MV/cm) was observed at the NKNS–CZ/SNO/Pt–Si bottom-electrode interface. Hence, the film exhibited relatively good insulating properties. The d33 and d33 × g33 values of the thin film were approximately 270 pm/V and 32.9 pm2/N, respectively. These are the largest d33 and d33 × g33 values reported until now. Therefore, the NKNS–CZ thin film shows excellent piezoelectric properties, and it can be used for fabricating thin-film piezoelectric energy harvesters.
Two-dimensional particle simulation of the boundary between a hot pair plasma and magnetized electrons and protons: Out-of-plane magnetic field
Authors: Dieckmann M. E. , Folini D. , Walder R. , Charlet A. , Marcowith A.
Published: September 2022

By means of a particle-in-cell (PIC) simulation, we study the interaction between a uniform magnetized ambient electron–proton plasma at rest and an unmagnetized pair plasma, which we inject at one simulation boundary with a mildly relativistic mean speed and temperature. The magnetic field points out of the simulation plane. The injected pair plasma expels the magnetic field and piles it up at its front. It traps ambient electrons and drags them across the protons. An electric field grows, which accelerates protons into the pair cloud's expansion direction. This electromagnetic pulse separates the pair cloud from the ambient plasma. Electrons and positrons, which drift in the pulse's nonuniform field, trigger an instability that disrupts the current sheet ahead of the pulse. The wave vector of the growing perturbation is orthogonal to the magnetic field direction and magnetic tension cannot stabilize it. The electromagnetic pulse becomes permeable for pair plasma, which forms new electromagnetic pulses ahead of the initial one. A transition layer develops with a thickness of a few proton skin depths, in which protons and positrons are accelerated by strong electromagnetic fields. Protons form dense clumps surrounded by a strong magnetic field. The thickness of the transition layer grows less rapidly than we would expect from the typical speeds of the pair plasma particles and the latter transfer momentum to protons; hence, the transition layer acts as a discontinuity, separating the pair plasma from the ambient plasma. Such a discontinuity is an important building block for astrophysical pair plasma jets.
Perpendicular magnetic anisotropy in as-deposited CoFeB/MgO thin films
Authors: Lou Kaihua , Xie Tunan , Zhao Qianwen , Jiang Baiqing , Xia ChaoChao , Zhang Hanying , Yao Zhihong , Bi Chong
Published: September 2022

Fabrication of perpendicularly magnetized ferromagnetic films on various buffer layers, especially on numerous newly discovered spin–orbit torque (SOT) materials to construct energy-efficient spin-orbitronic devices, is a long-standing challenge. Even for the widely used CoFeB/MgO structures, perpendicular magnetic anisotropy (PMA) can only be established on limited buffer layers through post-annealing above 300 °C. Here, we report that the PMA of CoFeB/MgO films can be established reliably on various buffer layers in the absence of post-annealing. Further results show that precise control of MgO thickness, which determines oxygen diffusion in the underneath CoFeB layer, is the key to obtain the as-deposited PMA. Interestingly, contrary to the previous understanding, post-annealing does not significantly influence the well-established as-deposited PMA but indeed enhances unsaturated PMA with a thick MgO layer by modulating oxygen distributions, rather than crystallinity or Co– and Fe–O bonding. Moreover, our results indicate that oxygen diffusion also plays a critical role in PMA degradation at high temperatures. These results provide a practical approach to build spin-orbitronic devices based on various high-efficient SOT materials.
Evaluation of water vapor condensation using the thermoelectric cooling technique by experimental and theoretical observations
Authors: Kumar Dinesh , Tiwari Akhilesh , Fontaine Jean-Pierre
Published: September 2022

The water vapor present in the atmosphere may be one of the sources of fresh and clean water. It is well known that 70% of the earth is covered with water. However, only less than 1% of fresh water is of direct use for humankind on earth. Several techniques have been devised to mitigate the availability of fresh water for humans. In this paper, a novel approach has been discussed to study the mass transfer from water vapor on a flat surface, and a moisture harvesting technique has been developed as a non-conventional source using the Peltier module to produce water condensate. The characterization of the flat surfaces has been done for the thermal homogeneity and the temperature gradient. The droplet nucleation process and the mass flux of water vapor from the air on the vertical surface at different temperatures have been devised. The results have been discussed for the mathematical calculation of the Reynolds number, Schmidt number, and Sherwood number using the experimental data. The comparison of experimental and theoretical mass fluxes was presented with an airflow velocity of less than 1.0 ms−1. The airflow on the condensing surface was a mixed type, and the coefficient of proportionality of the fluid flow was calculated as 0.23 for the proposed blunt-faced structure. The outcome was theoretically validated for the rate of condensation of water vapor from humid air and the mass flux produced. The technique developed may have several applications ranging from mass transfer in biotechnology to the nonconventional source of water production.
Impacts of various interfacial nanostructures on spectral phonon thermal boundary conductance
Authors: Xie Rui , Tiwari Janak , Feng Tianli
Published: September 2022

Nanoengineering of interfaces has become an effective way to tune the thermal boundary conductance (TBC) of heterostructures. However, the same nanostructure design can have opposite impacts on TBCs for different systems. To provide a clue toward a unified explanation, in this work, we directly and explicitly reveal the impacts of nanostructures on mode-dependent phonon TBC contributions. We study four representative types of nanostructures, i.e., (1) an intermediate layer, (2) interfacial interlaced teeth, (3) interfacial atomic mixing, and (4) interfacial atomic defects on two example heterostructures: 28Si/Ge and 6Si/Ge, which have moderate and large phonon frequency mismatches, respectively. We find that most of these nanostructures reduce the TBC of 28Si/Ge while increasing the TBC of 6Si/Ge. Each nanostructure is found to have two competing impacts on an interface—one tends to increase TBC while the other tends to decrease TBC. For example, adding an intermediate layer provides a phonon bridging effect, which tends to increase both elastic and inelastic phonon transmission, but it adds one more interface and, thus, more phonon reflection. As a result, an interlayer decreases the TBC of the 28Si/Ge interface by decreasing the inelastic transmission while increasing both elastic and inelastic transmissions of the 6Si/Ge interface. Other nanostructures with atomic disorder can increase transmission by increasing the contact area but can also decrease transmission by phonon-disorder backscattering. This work unveils the fundamental thermal transport physics across interfaces with nanostructures and sheds light on future interface nanoengineering for electronic devices such as high-power transistors, photodiodes, and supercomputing architectures.
Effect of gallium doping on structural and transport properties of the topological insulator Bi2Se3 grown by molecular beam epitaxy
Authors: Brito Daniel , Pérez-Rodriguez Ana , Khatri Ishwor , Tavares Carlos José , Amado Mario , Castro Eduardo , Diez Enrique , Sadewasser Sascha , Claro Marcel S.
Published: September 2022

Topological insulators possess non-conductive bulk and present surface states, henceforth, they are electrically conductive along their boundaries. Bismuth selenide (Bi2Se3) is one of the most promising topological insulators. However, a major drawback is its n-type nature arising from its natural doping, which makes the transport in the bulk dominant. This effect can be overcome by shifting the chemical potential into the bandgap, turning the transport of the surface states to be more pronounced than the bulk counterpart. In this work, Bi2Se3 was grown by molecular beam epitaxy and doped with 0.8, 2, 7, and 14 at. % of Ga, with the aim of shifting the chemical potential into the bandgap. The structural, morphological, and electronic properties of the Ga doped Bi2Se3 are studied. Raman and x-ray diffraction measurements confirmed the incorporation of the dopants into the crystal structure. Transport and magnetoresistance measurements in the temperature range of 1.5–300 K show that Ga-doped Bi2Se3 is n-type with a bulk charge carrier concentration of 1019 cm−3. Remarkably, magnetotransport of the weak antilocalization effect measurements confirms the existence of surface states up to a doping percentage of 2 at. % of Ga and coherence length values between 50 and 800 nm, which envisages the possibility of topological superconductivity in this material.
Pure circularly polarized light emission from waveguide microring resonators
Authors: Massai Leonardo , Schatteburg Tom , Home Jonathan P. , Mehta Karan K.
Published: September 2022

Circularly polarized light plays a key role in many applications, including spectroscopy, microscopy, and control of atomic systems. Particularly in the latter, high polarization purity is often required. Integrated technologies for atomic control are progressing rapidly, but while integrated photonics can generate fields with pure linear polarization, integrated generation of highly pure circular polarization states has not been addressed. Here, we show that waveguide microring resonators, perturbed with azimuthal gratings and thereby emitting beams carrying optical orbital angular momentum, can generate radiated fields of high circular polarization purity. We achieve this in a passive device by taking advantage of symmetries of the structure and radiated modes, and directly utilizing both transverse and longitudinal field components of the guided modes. On the axis of emission and at the maximum intensity, we measure an average polarization impurity of 1.0×10−3 in relative intensity across the resonance FWHM and observe impurities below 10−4 in this range. This constitutes a significant improvement over the ∼10−2 impurity demonstrated in previous works on integrated devices. Photonic structures that allow high circular polarization purity may assist in realizing high-fidelity control and measurement in atomic quantum systems.
Direction-dependent polarization modulation of Cherenkov diffraction radiation based on metasurfaces
Authors: Xu Wenxia , Li Wenjia , Jiang Zhaoqi , Sun Botian , Qin Chunhua , Lv Bo , Guan Chunying , Liu Jianlong , Shi Jinhui
Published: September 2022

The polarization modulation of Cherenkov diffraction radiation facilitates intriguing potentials to explore material properties and advanced technologies such as free-electron lasers; however, it is still challenging to achieve polarization modulation. Here, we propose versatile on-chip silicon-patterned silicon-nitride photonic integrated waveguides to produce a direction-dependent polarization modulator for Cherenkov diffraction radiation. The radiation angle can be manipulated arbitrarily by arranging the period of the grating and the propagation direction of the electron beam. Furthermore, the polarization and the number of output directions of the radiation can be controlled by the gradient metasurfaces. In particular, the linear, left-, and right-handed circular polarized Cherenkov diffraction radiation could be generated in separate radiation directions. Our results pave the way to modulate the polarization of free-electron radiation and further promote the development of on-chip light sources.
Thermodynamics, formation dynamics, and structural correlations in the bulk amorphous phase of the phase-field crystal model
Authors: Abdalla Shaho , Archer Andrew J. , Gránásy László , Tóth Gyula I.
Published: September 2022

We investigate bulk thermodynamic and microscopic structural properties of amorphous solids in the framework of the phase-field crystal (PFC) model. These are metastable states with a non-uniform density distribution, having no long-range order. From extensive numerical simulations, we determine the distribution of free energy density values in varying size amorphous systems and also the point-to-set correlation length, which is the radius of the largest volume of amorphous one can take while still having the particle arrangements within the volume determined by the particle ordering at the surface of the chosen volume. We find that in the thermodynamic limit, the free energy density of the amorphous tends toward a value that has a slight dependence on the initial state from which it was formed—i.e., it has a formation history dependence. The amorphous phase is observed to form on both sides of the liquid linear-stability limit, showing that the liquid to amorphous transition is first order, with an associated finite free energy barrier when the liquid is metastable. In our simulations, this is demonstrated when the noise in the initial density distribution is used to induce nucleation events from the metastable liquid. Depending on the strength of the initial noise, we observe a variety of nucleation pathways, in agreement with previous results for the PFC model, which show that amorphous precursor mediated multi-step crystal nucleation can occur in colloidal systems.
The effect of tilt on turbulent thermal convection for a heated soap bubble
Authors: He Xiao-Qiu , Xiong Yong-Liang , Bragg Andrew D. , Fischer Patrick , Kellay Hamid
Published: September 2022

We use direct numerical simulation (DNS) to explore the effect of tilt on two-dimensional turbulent thermal convection on a half-soap bubble that is heated at its equator. In the DNS, the bubble is tilted by an angle δ∈[0°,90°], the Rayleigh number is varied between Ra∈[3×106,3×109], and the Prandlt number is fixed at Pr = 7. The DNS reveals two qualitatively different flow regimes: the dynamic plume regime (DPR) and the stable plume regime (SPR). In the DPR, small dynamic plumes constantly emerge from random locations on the equator and dissipate on the bubble. In the SPR, the flow is dominated by a single large and stable plume rising from the lower edge of the bubble. The scaling behavior of the Nusselt number Nu and Reynolds number Re is different in these two regimes, with Nu∝Ra0.3 for the DPR and Nu∝Ra0.24 for the SPR. Concerning Re, the scaling in the DPR lies between Re∝Ra0.48 and Re∝Ra0.53 depending on Ra and δ, while in the SPR, the scaling lies between Re∝Ra0.44 and Re∝Ra0.45 depending on δ. The turbulent thermal and kinetic energy dissipation rates (εT′ and εu′, respectively) are also very different in the DPR and SPR. The probability density functions (PDF) of the normalized log εT′ and log εu′ are close to a Gaussian PDF for small fluctuations but deviate considerably from a Gaussian at large fluctuations in the DPR. In the SPR, the PDFs of normalized log εT′ and log εu′ deviate considerably from a Gaussian PDF even for small values. The globally averaged thermal energy dissipation rate due to the mean temperature field was shown to exhibit the scaling ⟨ε⟨T⟩⟩B∝Ra−0.23 in the DPR and ⟨ε⟨T⟩⟩B∝Ra−0.28 in the SPR. The globally averaged kinetic energy dissipation rate due to the mean velocity field is shown to exhibit the scaling ⟨ε⟨u⟩⟩B∝Ra−0.47 in the DPR (the exponent reduces from 0.47 to 0.43 as δ is increased up to 30°). In the SPR, the behavior changes considerably to ⟨ε⟨u⟩⟩B∝Ra−0.27. For the turbulent dissipation rates, the results indicate the scaling ⟨εT′⟩B∝Ra−0.18 and ⟨εu′⟩B∝Ra−0.29 in the DPR. However, the dependencies of ⟨εT′⟩B and ⟨εu′⟩B on Ra cannot be described by power-laws in the SPR.
Impact of ligand deformation on the P,T-violation effects in the YbOH molecule
Authors: Zakharova Anna , Petrov Alexander
Published: September 2022

Ytterbium monohydroxide is a promising molecule in the search for new physics. It is well known that levels of opposite parity, separated by energy split, the so-called l-doublets, define the experimental electric field strength required for molecule polarization. In addition, in our previous paper [Phys. Rev. A 105, L050801 (2022)], we have shown that the value of l-doubling directly influences the sensitivity of linear triatomic molecules toward the P,T-odd effects. In our work [J. Chem. Phys. 155, 164301 (2021)], we have calculated the value of l-doubling for YbOH molecules with the approximation of fixed O–H bond length. Taking the importance of this property into account, in the present study, we consider the additional degree of freedom corresponding to ligand (OH) deformation.
A wave function correction-based approach to the identification of resonances for vibrational perturbation theory
Authors: Boyer Mark A. , McCoy Anne B.
Published: September 2022

An approach for identifying resonances in vibrational perturbation theory calculations is introduced. This approach makes use of the corrections to the wave functions that are obtained from non-degenerate perturbation theory calculations to identify spaces of states that must be treated with degenerate perturbation theory. Pairs of states are considered to be in resonance if the magnitude of expansion coefficients in the corrections to the wave functions in the non-degenerate perturbation theory calculation is greater than a specified threshold, χmax. This approach is applied to calculations of the vibrational spectra of CH4, H2CO, HNO3, and cc-HOONO. The question of how the identified resonances depend on the value of χmax and how the choice of the resonance spaces affects the calculated vibrational spectrum is further explored for H2CO. The approach is also compared to the Martin test [J. M. L. Martin et al., J. Chem. Phys. 103, 2589–2602 (1995)] for calculations of the vibrational spectra of H2CO and cc-HOONO.
Systems and Dynamics
Authors: Vallero Daniel A.
Published: September 2022

This chapter discusses biogeochemical cycles involved in the transport, transformation, and fate of pollutants and other substances after they form and are released into the environment. These include carbon, nutrient, metals, and water cycles. The biogeochemical processes that form, transform, transport and lead to the fate of a substance are explained. Several examples are provided, including carbon equilibrium’s role in climate change and the environmental aspects of the speciation of mercury.