bluuebunny/crossref_metadata_2025 huggingface dataset:
Versorgungsnahe Daten für Versorgungsanalysen – Teil
3 des Manuals
Authors: Veit Christof , Bierbaum Thomas , Wesselmann Simone , Stock Stephanie , Heidecke Claus-Dieter , Apfelbacher Christian , Benz Stefan , Dreinhöfer Karsten E. , Hauptmann Michael , Hoffmann Falk , Hoffmann Wolfgang , Kaiser Thomas , Klinkhammer-Schalke Monika , Koller Michael , Kostuj Tanja , Ortmann Olaf , Schmitt Jochen , Schünemann Holger , Geraedts Max
Published: December 2022

Analysen zur Gesundheits- und Krankenversorgung (im Folgenden
„Versorgungsanalysen“) haben meist das Ziel, die Strukturen,
Prozesse, Ergebnisse und Wirkzusammenhänge von Versorgung transparent zu
machen und den Zielerreichungsgrad von Gesundheitssystemen und ihrer Akteure zu
erfassen. Versorgungsnahe Daten sind für viele Versorgungsanalysen eine
unverzichtbare Datenquelle. Voraussetzung für die
Überprüfung eines Zielerreichungsgrads ist zunächst eine
Einigung auf diejenigen Ziele, die vom System erreicht werden sollen, sowie die
Identifikation der Determinanten der Zielerreichung. Es geht vor allem darum zu
prüfen, wie sicher, effektiv und patient:innenzentriert Systeme,
Einrichtungen und Leistungserbringer arbeiten. Dabei werden auch Fragen des
Bedarfs, der Zugänglichkeit, Inanspruchnahme, Rechtzeitigkeit,
Angemessenheit, Patient:innensicherheit, Koordination, Kontinuität sowie
gesundheitsökonomischen Effizienz und Gerechtigkeit der
Gesundheitsversorgung thematisiert. Die Ergebnisse der Gesundheitsversorgung
bzw. der Systemkomponenten umfassen einerseits Systemleistungen (Outputs) und
andererseits Ergebnisse (Outcomes). Dabei sind die selbst berichteten Ergebnisse
(patient-reported outcomes, PROs) und Erfahrungen (patient-reported experiences,
PREs) von besonderer Bedeutung. Konkret geht es um die Grundfragen: wer macht
was, wann, wie, warum und mit welchen Ressourcen und Effekten in der
gesundheitlichen Routineversorgung. Versorgungsanalysen stellen die notwendigen
Erkenntnisse und Kennzahlen bereit, um Gesundheitsversorgung weiterentwickeln
und die Qualität der Versorgung verbessern zu können. Die
Anwendungsgebiete reichen von Kapazitätsanalysen über
Innovationsbegleitung bis hin zum Konzept des Monitoring regionaler und
überregionaler Systemqualität. Angesichts der zunehmenden
Digitalisierung im Gesundheitswesen stehen künftig versorgungsnahe Daten
vermehrt für Versorgungsanalysen zur Verfügung. Gezielt und
methodisch korrekt eingesetzt können diese die Versorgenden erheblich
unterstützen und damit die Versorgungsqualität für die
Patient:innen entscheidend verbessern helfen. Versorgungsnahe Daten haben ein
großes Potential. Ihre Anwendung bedarf aber der gleichen
wissenschaftlichen Akribie, die auch für andere Formen
wissenschaftlicher Studien gilt.
Comparative Investigation of Electrocatalytic Oxidation of Cyclohexene by Proton-Exchange Membrane and Anion-Exchange Membrane Electrolyzers
Authors: Shida Naoki , Atobe Mahito , Ido Yuto , Shimizu Yugo
Published: December 2022

Electrocatalytic oxidation of cyclohexene was performed in proton-exchange membrane (PEM) and anion-exchange membrane (AEM) electrolyzers. For the efficient electrocatalytic oxidation, the anode catalyst material, applied potential, and solvent used were optimized. In addition, the differences in reactivity between the PEM and AEM electrolyzers were clarified and a mechanism for the oxidation of cyclohexene in each electrolyzer was proposed.
Acromioclavicular Joint Injury and Repair
Authors: Baren James P. , Rowbotham Emma , Robinson Philip
Published: December 2022

The acromioclavicular (AC) joint is commonly injured in athletes participating in contact and overhead throwing sports. Injuries range from simple sprains to complete ligamentous disruption, and they are classified by the established Rockwood grading system. High-grade injuries are associated with fractures around the AC joint and disruption of the superior shoulder suspensory complex, a ring of osseous and ligamentous structures at the superior aspect of the shoulder. Radiographs are the mainstay of imaging of the AC joint, with magnetic resonance imaging reserved for high-grade injuries to aid classification and plan surgical management. Low-grade AC joint injuries tend to be managed conservatively, but a wide range of surgical procedures have been described for higher grade injuries and fractures around the AC joint. This review illustrates the anatomy of the AC joint and surrounding structures, the imaging features of AC joint injury, and the most commonly performed methods of reconstruction and their complications.
Total Synthesis of Patulone: A Natural Xanthonoid Possessing a Geminally Diisoprenylated Structure
Authors: Matsumoto Takashi , Kobayashi Ryouma , Watabe Yu , Fujimoto Yuuki , Yanai Hikaru
Published: December 2022

The first total synthesis of patulone, a plant metabolite possessing a unique 1,1-diisoprenyl-1H-xanthene-2,9-dione structure, is described. Starting from a 1-fluroxanthone derivative with suitable substitution pattern, the pivotal gem-diisoprenylation was efficiently accomplished by implementing twice the sequence of addition of isoprenyl Grignard reagent to the carbonyl at C9 and anion-accelerated oxy-Cope rearrangement.
Muscle Injury Around the Shoulder
Authors: Jacob J. , O'Connor P. , Pass B.
Published: December 2022

Acute shoulder tendon and intra-articular injuries are common and their imaging well described. However, a subset of patients present with more unusual acute shoulder muscle injury. Of these, pectoralis major muscle injuries are encountered the most often and are increasingly prevalent due to a focus on personal fitness, particularly bench-press exercises. Other muscle injuries around the shoulder are rare. This article reviews the anatomy, mechanism of injury, and the imaging findings in relation to injuries of these muscles around the shoulder. We focus on pectoralis major injury but also review proximal triceps, latissimus dorsi, teres major, and deltoid muscle injuries, providing imaging examples.
Endovascular Management of Acute Iliofemoral Deep Vein Thrombosis
Authors: Huang Michael H. , Benishay Elana T. , Desai Kush R.
Published: December 2022

Lower extremity deep vein thrombosis (DVT) is frequently encountered in clinical practice. Postthrombotic syndrome (PTS) is a common sequela of DVT and encompasses a wide variety of symptoms, including severe pain, edema, and ulceration, all of which may contribute to a negative impact on quality of life. Studies have demonstrated that acute thrombosis of the iliofemoral venous segment is correlated with high rates of PTS, increased severity of symptoms, and high rates of thrombus recurrence, despite patients receiving treatment with standard-of-care anticoagulation therapy. Endovascular interventions, including catheter-directed thrombolysis, pharmacomechanical thrombectomy, and mechanical thrombectomy, have generated significant interest as a method for reduction of short-term symptom severity and potential reduction of downstream PTS severity. While there is high-quality evidence evaluating the role of catheter-directed and pharmacomechanical thrombectomy for acute iliofemoral DVT, newer mechanical-only devices that utilize thrombectomy without fibrinolytic medication are less studied. Currently, there are limited data evaluating the efficacy and safety of these treatment modalities, although investigations are ongoing.
Two-Year Survivorship and Outcomes of a Three-Dimensional Printed Metaphyseal Cone in the Setting of Revision Total Knee Arthroplasty
Authors: Monárrez Rubén , Bains Sandeep S. , Chen Zhongming , Sax Oliver C. , Salib Christopher G. , Mont Michael A. , Delanois Ronald E.
Published: December 2022

Poor metaphyseal fixation secondary to bone loss in revision total knee arthroplasty (TKA) continues to be challenging. One technique to increase implant stability is the use of novel three-dimensional (3D) printed titanium metaphyseal cones with adjunctive stems for added fixation. However, the survival of these novel constructs is poorly understood. Therefore, we sought to examine 3D-printed titanium metaphyseal cone components in revision TKA for aseptic as well as septic reasons and aimed to evaluate: (1) revision-free survivorships; (2) patient-reported outcomes measures (PROMs); (3) postoperative medical complications; and (4) radiographic outcomes. A consecutive series of 62 patients who underwent revision TKA with use of a titanium metaphyseal cone at a single institution between September 1, 2015 and May 31, 2021 were examined. The patients had a minimum follow-up period of 2 years (mean, 40 months, range, 24–72 months). PROMS included Knee Injury and Osteoarthritis Outcome Score Joint Replacement (KOOS-JR) scores at baseline and last clinical follow-up. Overall, when excluding infections, the combined implant survivorship was 96% (52 out of 54), while it was 95% (35 out of 57) for aseptic revisions and 100% (17 out of 17) for septic revisions. Reasons for revisions within the aseptic revision cohort included loosening (5%) as well as periprosthetic joint infections (PJIs) (7.5%). All failures following an index septic revision were due to PJI. Mean KOOS scores at baseline as well as at final follow-up was 43 points (range, 16–80) and 70 points (range, 34–100), respectively. None of the patients had medical complications. Other than the loosening reported (only femoral component), of the surviving patients no patients had evidence of progressive radiolucencies. The use of titanium cones in revision TKA provides good revision-free survivorship at 2 years. Further research is warranted on the longer-term survivorship of 3D-printed titanium cones. The current study has found that 3D-printed titanium cones can be incorporated as part of the revision knee surgeon's armamentarium.
Dressing Management during Total Knee Arthroplasty: A Systematic Review and Meta-Analysis
Authors: Chen Zhongming , Bains Sandeep S. , Sax Oliver C. , Sodhi Nipun , Mont Michael A.
Published: December 2022

Dressings for total knee arthroplasty (TKA) typically focus on promoting optimal healing, while preventing infection, allowing for functionality and immediate ambulation, while providing for excellent cosmesis. We have previously described four aspects of closure after TKA involving the: (1) deep fascial layer; (2) subdermal layer; (3) intradermal layer, including the subcuticular region; and (4) a specific aseptic dressing. In this meta-analysis and systematic review of the literature, we will focus on the dressing. Specifically, we assessed: (1) infection risk of different techniques; (2) re-operation or readmission risk; and (3) length of time until dressing change needed. There were 16 reports on infection risk, re-operation risk, and length of time until change needed. A meta-analysis focused on the qualifying wound complication risk reports was also performed. The meta-analysis including four studies (732 patients) demonstrated overall lower wound complication risk with the use of adhesives and mesh dressings (odds ratio 0.67) versus traditional closures. Additionally, studies demonstrated fewer re-operations and readmissions with the use of adhesives and mesh dressings. Furthermore, one report demonstrated mesh dressings persist longer than silver dressings. Therefore, multiple recent reports suggest superior outcomes when using adhesive and mesh dressings for TKAs.
Disseminated Gonococcal Infection Caused by a Multidrug-Resistant Pathogen Presenting with Hemorrhagic Manifestation: A Case Report
Authors: Mohammed Yahaya , Umar Amina Gambo , Sabitu Muhammad Zainu , Bello Saratu , Umar Muktar , Jimoh Ahmed Kolawole , Aliyu Fatima Birnin Yauri , Abubakar Jibril
Published: December 2022

The incidence of disseminated gonococcal infection (DGI) is rising in some parts of the world, but there is paucity of data on its true incidence from sub-Saharan Africa. DGI has varied manifestations in different population group. We report a case of a 30-year-old sexually active woman presenting with hemorrhagic symptoms 2 weeks after a surgery on account of diagnosis of uterine fibroid made at a peripheral hospital. A multidrug-resistant Neisseria gonorrhoeae was isolated from the wound on her surgical site and blood sample. She was managed with intravenous meropenem, pressure dressing, and blood products, with the patient making a full recovery after a week. This case is presented because it is a rare one. Moreover, there is the need to revive the awareness of clinicians on the existence of multidrug-resistant gonococcus in our environment. We herein report a case of DGI from Nigeria.
Prognostic Factors in Patients with Clinic Locally Advanced T4 Lung Cancer: Surgical Considerations
Authors: Kaba Erkan , Cosgun Tugba , Yardimci Halit , Toker Alper
Published: December 2022

Background Inclusion of surgery in the treatment of T4 lung cancer has been a debate for the last two decades. The aim of this study is to investigate the potential prognostic factors which could affect the outcome.

Methods Fifty-seven clinical T4 non-small cell lung carcinoma (NSCLC) patients out of 716 lung resections, who were operated at a single institution in 7 years period, were included in this study. Patients are grouped into three groups as patients with neoadjuvant treatment group (group 1 n: 16), salvage surgery group (surgery after 3 months of definitive chemotherapy and radiotherapy) (group 2 n: 14), and straightforward surgery group (group 3 n: 27) with adjuvant treatment. Groups were analyzed and compared in terms of postoperative complications, 30 days of mortality, disease free survival, and overall survival.

Results Mean overall survival (OS) was 48.43 ± 4.4 months and mean disease-free survival (DFS) 40.55 ± 4.46 months for all patients. Thirty days mortality was 5.2% and complication rates were 63.1%. Two years OS was 61.4 ± 6.4%, DFS was 58.1 ± 7.8%. Group 1, Group 2, and Group 3 patients had mean 39.14 ± 5.6, 44.7 ± 7.1, and 62.9 ± 4.8 months for OS (p: 0.09), and 29.6 ± 7.2, 38.4 ± 9.1, and 46.9 ± 6 months for DFS (p: 0.27). Patients who received blood transfusion showed significantly worse outcomes (p: 0.001 for DFS and p: 0.004 for OS).

Conclusion According to our outcomes, surgery should be included in the treatment of clinical T4 lung cancer when physiologically and oncologically possible with careful patient selection. This study demonstrates that patients receiving straightforward surgery have longer survival, in spite of higher perioperative mortality rate. Risks and benefits should be considered carefully.
Development of multichord ion Doppler spectroscopy system for toroidal flow measurement of field-reversed configuration
Authors: Araoka K. , Asai T. , Kobayashi D. , Seki T. , Takahashi T. , Morelli J. , Gota H.
Published: December 2022

A double-chord ion Doppler spectroscopy (IDS) system was developed to measure the ion temperature and flow velocity of field-reversed configuration (FRC) plasmas in the FRC amplification via a translation-collisional merging (FAT-CM) device. Adopting a Czerny–Turner mount monochromator and 16-channel photomultiplier tube array, the developed IDS system achieves high wavelength resolution and fast time response. In addition, two vertically aligned optical paths share the optical system up to the monochromator and then branch just before the detector, successfully reducing crosstalk to <1%. The Doppler broadening was measured at two measurement points in the FAT-CM device, simultaneously, and ion temperatures of ∼50 eV were measured. Toroidal spin-up from 7 to 15 km/s and a steady flow velocity of ∼10 km/s were estimated from the Doppler shift obtained by the developed system. The observation of the toroidal flow velocity and the spatial profile of the ion temperature of the FRC plasma in the FAT-CM device were realized. These spectroscopic diagnostic’s double chord capabilities will aid in understanding and improving the FRC plasmas.
Precise quantum measurement of vacuum with cold atoms
Authors: Barker Daniel S. , Acharya Bishnu P. , Fedchak James A. , Klimov Nikolai N. , Norrgard Eric B. , Scherschligt Julia , Tiesinga Eite , Eckel Stephen P.
Published: December 2022

We describe the cold-atom vacuum standards (CAVS) under development at the National Institute of Standards and Technology (NIST). The CAVS measures pressure in the ultra-high and extreme-high vacuum regimes by measuring the loss rate of sub-millikelvin sensor atoms from a magnetic trap. Ab initio quantum scattering calculations of cross sections and rate coefficients relate the density of background gas molecules or atoms to the loss rate of ultra-cold sensor atoms. The resulting measurement of pressure through the ideal gas law is traceable to the second and the kelvin, making it a primary realization of the pascal. At NIST, two versions of the CAVS have been constructed: a laboratory standard used to achieve the lowest possible uncertainties and pressures, and a portable version that is a potential replacement for the Bayard–Alpert ionization gauge. Both types of CAVSs are connected to a combined extreme-high vacuum flowmeter and dynamic expansion system to enable sensing of a known pressure of gas. In the near future, we anticipate being able to compare the laboratory scale CAVS, the portable CAVS, and the flowmeter/dynamic expansion system to validate the operation of the CAVS as both a standard and vacuum gauge.
Droplet transition from non-axisymmetric to axisymmetric shape: Dynamic role of lubrication film in a rectangular microfluidic channel
Authors: Zamboni R. , Zaltron A. , Ferraro D. , Sada C.
Published: December 2022

In the past 20 years, droplet microfluidics is burgeoning in many chemical and biological applications due to the unique capability of droplets to act as confined containers. Confinement is ensured even in the case of squeezed droplets within microchannels much smaller than droplet volumes due to the presence of a lubrication thin film that prevents contact between droplets and the channel walls. The thickness of the lubrication film depends on the dynamics of the entire microfluidic system, affecting the actual droplet's shape and velocity. Therefore, this film is extensively studied to obtain insight into the dynamics of flowing droplets, especially when confined in small channels. Circular cross section channels are the most studied for their axial symmetry, but practical applications present most likely non-axisymmetric channels, as a result of fabrication processes, such as soft lithographic rectangular channels. The latter showed unique transitional morphological behavior of droplets, which assumes an axisymmetric or non-axisymmetric shape during their flow inside a non-axisymmetric channel, depending on the lubrication film. This work gives a comprehensive experimental characterization of the dynamics of the lubrication film during the droplet shape transition. We settled on a novel approach based on the optical diffraction of a localized light beam provided by two-facing optical waveguides integrated with the microfluidics circuit. The technique allows for studying the dynamics of flowing droplets and their relationship with the lubrication film thickness. Additionally, this experimental system enables a precise definition of two regimes of lubrication film, and the critical capillary number at which the transition occurs.
Effect of antiferromagnetic order on a propagating single-cycle THz pulse
Authors: Metzger T. W. J. , Grishunin K. A. , Afanasiev D. , Dubrovin R. M. , Mashkovich E. A. , Pisarev R. V. , Kimel A. V.
Published: December 2022

Employing polarization sensitive terahertz (THz) transmission spectroscopy, we explored how the waveform of initially single-cycle linearly polarized THz pulses changes upon propagation through a thick antiferromagnetic crystal of CoF2. The changes upon propagation through CoF2 are found to depend strongly on both the incoming polarization and temperature. In particular, the ellipticity and polarization rotation acquired by initially linearly polarized light are quantified and explained in terms of magnetic linear birefringence and dichroism. Although the magneto-optical effects are often considered to be relatively weak, our experiments reveal that the polarization of the THz pulse substantially changes along the pulse duration. The pulse shape is further complicated by features assigned to the formation of magnon-polaritons. The findings clearly show the importance of accounting for propagation effects in antiferromagnetic spintronics and magnonics.
Structure optimization with stochastic density functional theory
Authors: Chen Ming , Baer Roi , Rabani Eran
Published: December 2022

Linear-scaling techniques for Kohn–Sham density functional theory are essential to describe the ground state properties of extended systems. Still, these techniques often rely on the localization of the density matrix or accurate embedding approaches, limiting their applicability. In contrast, stochastic density functional theory (sDFT) achieves linear- and sub-linear scaling by statistically sampling the ground state density without relying on embedding or imposing localization. In return, ground state observables, such as the forces on the nuclei, fluctuate in sDFT, making optimizing the nuclear structure a highly non-trivial problem. In this work, we combine the most recent noise-reduction schemes for sDFT with stochastic optimization algorithms to perform structure optimization within sDFT. We compare the performance of the stochastic gradient descent approach and its variations (stochastic gradient descent with momentum) with stochastic optimization techniques that rely on the Hessian, such as the stochastic Broyden–Fletcher–Goldfarb–Shanno algorithm. We further provide a detailed assessment of the computational efficiency and its dependence on the optimization parameters of each method for determining the ground state structure of bulk silicon with varying supercell dimensions.
Hard-disk pressure computations—a historic perspective
Authors: Li Botao , Nishikawa Yoshihiko , Höllmer Philipp , Carillo Louis , Maggs A. C. , Krauth Werner
Published: December 2022

We discuss pressure computations for the hard-disk model performed since 1953 and compare them to the results that we obtain with a powerful event-chain Monte Carlo and a massively parallel Metropolis algorithm. Like other simple models in the sciences, such as the Drosophila model of biology, the hard-disk model has needed monumental efforts to be understood. In particular, we argue that the difficulty of estimating the pressure has not been fully realized in the decades-long controversy over the hard-disk phase-transition scenario. We present the physics of the hard-disk model, the definition of the pressure and its unbiased estimators, several of which are new. We further treat different sampling algorithms and crucial criteria for bounding mixing times in the absence of analytical predictions. Our definite results for the pressure, for up to one million disks, may serve as benchmarks for future sampling algorithms. A synopsis of hard-disk pressure data as well as different versions of the sampling algorithms and pressure estimators are made available in an open-source repository.
Surfactant induced gelation of TEMPO-oxidized cellulose nanofibril dispersions probed using small angle neutron scattering
Authors: Schmitt Julien , Calabrese Vincenzo , da Silva Marcelo A. , Hossain Kazi M. Z. , Li Peixun , Mahmoudi Najet , Dalgliesh Robert M. , Washington Adam L. , Scott Janet L. , Edler Karen J.
Published: December 2022

In this work, we studied TEMPO-oxidized cellulose nanofibril (OCNF) suspensions in the presence of diverse surfactants. Using a combination of small angle neutron scattering (SANS) and rheology, we compared the physical properties of the suspensions with their structural behavior. Four surfactants were studied, all with the same hydrophobic tail length but different headgroups: hexaethylene glycol mono-n-dodecyl ether (C12EO6, nonionic), sodium dodecyl sulfate (SDS, anionic), cocamidopropyl betaine (CapB, zwitterionic), and dodecyltrimethylammonium bromide (DTAB, cationic). Contrast variation SANS studies using deuterated version of C12EO6 or SDS, or by varying the D2O/H2O ratio of the suspensions (with CapB), allowed focusing only on the structural properties of OCNFs or surfactant micelles. We showed that, in the concentration range studied, for C12EO6, although the nanofibrils are concentrated thanks to an excluded volume effect observed in SANS, the rheological properties of the suspensions are not affected. Addition of SDS or CapB induces gelation for surfactant concentrations superior to the critical micellar concentration (CMC). SANS results show that attractive interactions between OCNFs arise in the presence of these anionic or zwitterionic surfactants, hinting at depletion attraction as the main mechanism of gelation. Finally, addition of small amounts of DTAB (below the CMC) allows formation of a tough gel by adsorbing onto the OCNF surface.
Data-driven discovery of the governing equation of granular flow in the homogeneous cooling state using sparse regression
Authors: Zhao Bidan , He Mingming , Wang Junwu
Published: December 2022

With the arrival of the era of big data and the rapid development of high-precision discrete simulations, a wealth of high-quality data is readily available, but discovering physical laws from these data remains a great challenge. In this study, an attempt is made to discover the governing equation of the granular flow for the homogeneous cooling state from discrete element method (DEM) data through sparse regression. It is shown that not only the governing equation but also the energy dissipation rate can be obtained accurately from DEM data for systems having different physical properties of particles and operating conditions. The present work provides the evidence that the macroscopic governing equation and the constitutive relation of granular flow can be discovered from microscopic data using a purely data-driven method.
UV–Vis–NIR broad spectral photodetectors facilely fabricated with nonmetal plasmonic WO3−x nanosheets
Authors: Wang Dongran , Xia Kai , Tang Haibin , Huang Zhulin , Zhang Yao , Wang Xiujuan , Fei Guangtao , Meng Guowen
Published: December 2022

Plasmonic metal nanostructures have been widely applied in photodetectors for the enhanced light response range and sensitivity. In contrast, photodetection based on surface plasmon effect of the emerging plasmonic nonmetals has not been investigated. Here, single nonmetal plasmonic WO3−x nanosheets were used as the sensing material for UV–Vis–NIR broad spectral photodetectors. The plasmonic WO3−x nanosheets were synthesized by solvothermal and follow-up thermal treatment in a hydrogen-containing atmosphere, which exhibited a localized surface plasmon resonance (LSPR) band centered at 899 nm with broad spectral absorption spanned from UV to NIR. Then photodetectors fabricated facilely by depositing Au electrodes on a film of WO3−x nanosheets showed sensitive response for the regulation of conductance through the plasmonic hot free charge carriers. The responsivity and detectivity were 52 mA/W and 1.46 × 108 Jones under an incident light with a wavelength of 980 nm with an ultralow bias of 0.01 V, and went up to 538 mA/W and 4.75 × 108 Jones under 0.1 V. The results demonstrate the great potential of nonmetal plasmonic materials for photodetection.
Accurate Hellmann–Feynman forces from density functional calculations with augmented Gaussian basis sets
Authors: Pathak Shivesh , López Ignacio Ema , Lee Alex J. , Bricker William P. , Fernández Rafael López , Lehtola Susi , Rackers Joshua A.
Published: December 2022

The Hellmann–Feynman (HF) theorem provides a way to compute forces directly from the electron density, enabling efficient force calculations for large systems through machine learning (ML) models for the electron density. The main issue holding back the general acceptance of the HF approach for atom-centered basis sets is the well-known Pulay force which, if naively discarded, typically constitutes an error upward of 10 eV/Å in forces. In this work, we demonstrate that if a suitably augmented Gaussian basis set is used for density functional calculations, the Pulay force can be suppressed, and HF forces can be computed as accurately as analytical forces with state-of-the-art basis sets, allowing geometry optimization and molecular dynamics to be reliably performed with HF forces. Our results pave a clear path forward for the accurate and efficient simulation of large systems using ML densities and the HF theorem.
A new linear stability analysis approach for microchannel flow based on the Boltzmann Bhatnagar–Gross–Krook equation
Authors: Zou Sen , Zhong Chengwen , Bi Lin , Yuan Xianxu , Tang Zhigong
Published: December 2022

Microchannels are important components of microelectromechanical systems (MEMSs) that encounter rarefaction effects due to their small-scale characteristics. The influence of rarefaction effects on the flow stability of microchannels should be investigated to improve MEMS performance. Based on kinetic theory, a linear stability analysis approach for low-speed rarefied flows was developed by using the Bhatnagar–Gross–Krook (BGK) model of the Boltzmann equation with an external force term. This approach was applied to study the linear temporal stability of microchannel flows. A slip flow model was introduced for comparison. The corresponding eigenvalue problem was solved with a Chebyshev collocation method. This novel approach yielded a critical Reynolds number of 5778. Analysis of the validity and accuracy of the slip flow model shows that although this model cannot capture the Knudsen layer structure, this approach effectively improves the prediction accuracy of the growth rate of the least stable mode. However, the prediction accuracy gradually decreases with increasing Knudsen number. Compared with the stability results obtained from the BGK equation, the Navier–Stokes equations-based stability analysis method always underestimates the disturbance growth rate, regardless of whether a slip flow model is used. The stability analysis results show that rarefaction effects stabilize the flow. The degree of rarefaction does not affect the trends of growth rate and phase velocity with wavenumber, nor does it affect the shape of the velocity eigenfunctions. For a rarefied case, increasing the Mach number has a destabilizing effect on low-speed microchannel flows.
Time-resolved particle-scale dynamics of a particle-laden jet
Authors: Li Qingzhan , Zhu Renshuai , Wang Wei , Chen Yanpei , Li Fei , Furuhata Tomohiko
Published: December 2022

Particle-laden jet flow is important to both jet-related industry applications and transmission of the virus through violent expiratory events, such as coughing and sneezing. To help understand its dynamics from the particle level, we develop a time-resolved, three-dimensional (3D), particle tracking velocimetry method, coupled with particle image velocimetry measurement of gas flow, and perform experiments on a dilute particle-laden gas jet. The spatial distributions of velocity and fluctuating velocity of the gas and particles are obtained. It is found that the presence of particles significantly changes the gas turbulence and stretch the gas flow field to the downstream. The probability density function of axial particle velocity shows non-Gaussian distribution and deviates much from those of the spanwise velocities, indicating strong non-equilibrium and anisotropic states. A new drag model is derived based on the reconstructed particle trajectories and gas flow field near the ejector exit with particle Reynolds numbers between 30 and 300. It is found in better agreement with the experimental data than the standard single-particle drag model. A simple model relating the particle volume fraction with particle displacement is developed based on the self-similarity theory of jet, showing good agreement with the experimental measurement.
Flow structure beneath periodic waves with constant vorticity under normal electric fields
Authors: Flamarion M. V. , Gao T. , Ribeiro-Jr R. , Doak A.
Published: December 2022

Waves with constant vorticity and electrohydrodynamics flows are two topics in fluid dynamics that have attracted much attention from scientists for both the mathematical challenge and their industrial applications. Coupling of electric fields and vorticity is of significant research interest. In this paper, we study the flow structure of steady periodic traveling waves with constant vorticity on a dielectric fluid under the effect of normal electric fields. Through the conformal mapping technique combined with pseudo-spectral numerical methods, we develop an approach that allows us to conclude that the flow can have zero, two, or three stagnation points according to variations in the voltage potential. We describe in detail the recirculation zones that emerge together with the stagnation points. In addition, we show that the number of local maxima of the pressure on the bottom boundary is intrinsically connected to the saddle points.
Cost reduction for data acquisition based on data fusion: Reconstructing the surface temperature of a turbine blade
Authors: Wen Fengbo , Li Zuobiao , Wan Chenxin , Su Liangjun , Zhao Zhiyuan , Zeng Jun , Wang Songtao , Pan Binghua
Published: December 2022

Turbine cooling is an effective way to improve the comprehensive performance and service life of gas turbines. In recent decades, there has been rapid growth in research into external cooling and internal cooling methods. As a result, there is a significant amount of experimental and numerical data. However, due to their multi-source nature, the datasets have different degrees of fidelity and different data structures, which hinder the effective use of the data. Besides, high-fidelity (HF) data often have high acquisition costs, which hinder their application in aerospace. A novel form of data fusion is introduced in this paper. We integrate multi-source data using special algorithms to produce more reliable data. A deep-learning neural network with the PointNet architecture is designed to establish two surrogate models: a high-fidelity model (HF model) trained by experimental data and a low-fidelity model (LF model) based on Reynolds-averaged Navier–Stokes simulation data. Both models predict results with less than 1% reference errors compared to their respective ground truth at most data points. In addition, we explore the role of transfer learning in multi-fidelity modeling. A fusion algorithm based on a Gaussian function and a weighted average strategy is proposed to combine the values from the HF model and the LF model. The presented results show that the fusion data are more accurate than computational fluid dynamics data, successfully meeting the goal of reducing the cost of data acquisition.
Modeling of droplet dynamics with soluble surfactant by multi-relaxation-time phase-field lattice Boltzmann method
Authors: Zhou Wenning , Xing Yufu , Liu Xunliang , Yan Yuying
Published: December 2022

The multiphase fluid system in the presence of surfactant is frequently encountered in numerous scientific and engineering applications. Developing a model for accurately simulating such a complex system is of great significance. In this work, we propose a multi-relaxation-time phase-field lattice Boltzmann model for simulating droplet dynamics with soluble surfactants. The accuracy and validity of the model are verified by benchmark cases including static droplet and Rayleigh–Taylor instability tests. The effects of surfactant, capillary number, and density ratio on single-droplet deformation and two-droplet interaction under shear flow are investigated. Simulation results indicate that the Marangoni stress generated by the inhomogeneous distribution of surfactant at the interface plays the role of promoting droplet deformation and hindering droplet coalescence. Within the studied range, it tends to be much easier for droplets to deform with the decrease in density ratio. The increase in the capillary number and surfactant concentration is conducive to promoting the deformation and breakup of droplets. In addition, a higher surfactant concentration is found to result in greater liquid film thickness between droplets, which would hinder the coalescence of the droplets.
Thermal gradient and elastic dependence of induced charge electro-osmosis in viscoelastic fluids
Authors: Chen Di-Lin , Luo Xiao-Ping , Su Zheng-Gang , Luo Kang , Yi Hong-Liang
Published: December 2022

Induced charge electro-osmosis has notable implementation possibilities in thermal management and efficient electrokinetic micropumps. We present the coupled numerical implementation around a polarized cylinder subject to an external electric field with the influence of different polymer elasticity and thermal gradients. The azimuthal velocity, flow types, kinetic energy, elastic energy, ion transport behavior, and heat transfer capability are investigated in detail. The results show that the inflow and outflow rates approximately overlap for a typical small voltage limit ϕ < 0.1. The Rayleigh number (Ra) significantly influences the elastic energy accumulation and evolution time to the final steady state. The thermal buoyancy forces are not sufficient to create typical thermogravitational convection with passive heat transfer when Ra < 1.3 × 10−3, resulting in heat diffusion and electro-osmosis velocity dominating the temperature distribution. The Nusselt number (Nu) plot with a weak viscoelastic effect implies an asymptotic Nu=0.44+2.65Ra0.35 relation. Relevant results open possibilities for enhanced mixing and heat transfer in microdevices, providing insight into barriers to the non-Newtonian nature of electrokinetic dynamics.
Dynamic stall of pitching tubercled wings in vortical wake flowfield
Authors: Zhao Ming , Xu Lianchao , Li Xiaojian , Zhao Yijia , Liu Zhengxian
Published: December 2022

In consideration of the turbulent inflow condition of engineering applications, the flow mechanisms of dynamic stall of a tubercled airfoil have been comprehensively analyzed with an upstream cylinder. Numerical simulation of the flowfield of a tubercled wing with NACA0021 (National Advisory Committee for Aeronautics) airfoil has been conducted with the large eddy simulation model. Then, flow mechanisms have been analyzed based on the aerodynamic performances and flow structure descriptions. Meanwhile, proper orthogonal decomposition (POD) analysis has been carried out at both trough and peak sections to reveal the flow dynamics. It turns out that the dynamic stall process vanishes, and performances would be obviously impacted by the incoming cylinder wake in the case of αA=5° due to the enforced resistance of adverse pressure gradient. Furthermore, the first leading POD mode corresponds to the pitching movement at both trough and peak sections, while the high-order modes represent the influence of cylinder wake. Eventually, the influence of pitching amplitude has also been discussed in the case of αA=15°. Different from the case of αA=5°, dynamic stall phenomenon emerges, and the influence of wake impingement could be barely detected from the mode information except for the third mode at the trough section. The detachment of the dynamic stall vortex takes place corresponding to the dynamic stall onset, which is driven by the streamwise pressure gradient near the trough leading-edge.
Measurement and modeling of uniaxial and planar extensional viscosities for linear isotactic polypropylenes
Authors: Drabek Jiri , Zatloukal Martin
Published: December 2022

In this work, novel rectangular and circular orifice (zero-length) dies were used to measure planar and uniaxial extensional viscosities as a function of strain rate for various linear isotactic polypropylene melts by using Cogswell methodology. The obtained experimental data were combined with shear and uniaxial extensional viscosity data determined at very high strain rates. The ability of the molecularized generalized Newtonian fluid (mGNF) [M. Zatloukal and J. Drabek, “Generalized Newtonian fluid constitutive equation for polymer liquids considering chain stretch and monomeric friction reduction for very fast flows modeling,” Phys. Fluids 33(8), 083106 (2021)], Giesekus, and explicit Yao constitutive equations to describe the measured data was tested. It has been shown that including the effect of the chemical environment (i.e., the role of the oligomeric solvent) using a simplified version of the mGNF constitutive equation (instead of the commonly used Newton's law) can significantly improve the ability of the Giesekus and Yao viscoelastic constitutive equations to describe the measured experimental data, especially at very high strain rates with using adjustable parameters with a clear physical meaning.
The ecology, evolution and management of mast reproduction in Australian plants
Authors: Wright Boyd R. , Franklin Donald C. , Fensham Roderick J.
Published: December 2022

Australia is home to a diverse assemblage of plant species that display marked population-level variation in inter-annual flower or seed output (i.e. masting). These include a semelparous bamboo with an estimated inter-crop period of 40–50 years, numerous iteroparous masting gymnosperms, angiosperms that include landscape-dominant eucalypts, arid-zone wattles and spinifex (Triodia spp.) grasses, and a rich selection of species that display disturbance-related forms of masting such as pyrogenic flowering and environmental prediction. Despite the prevalence of masting in the Australian flora, there has been a paucity of research on these plants. Nevertheless, from the literature available, it appears that, similar to other parts of the world, a continuum of inter-year reproductive variability exists, with a small number of species displaying extreme–high inter-annual seeding variability. From experimental studies and many anecdotal reports, most of the fitness benefits associated with masting evident overseas also operate in Australia (e.g. predator satiation, improved pollination efficiency, and environmental prediction). Additionally, some Australian masting species offer periodically important food resources for Aboriginal nations in the form of seed or fruit. These include the bunya pine (Araucaria bidwillii), members of the cycad genera Cycas and Macrozamia, spinifex (Triodia) grasses, and mulga shrubs (Acacia aneura). Key future research areas for effective conservation of Australian masting plants include (1) improved understanding of how management interventions such as burning and silvicultural thinning influence regeneration dynamics and higher-order trophic interactions, (2) further longitudinal monitoring across a range of habitats to identify other, as yet unknown, species that display reproductive intermittency, and (3) elucidation of how changes to temperature, precipitation and fire regimes under climate change will affect reproduction and regeneration dynamics of the Australian masting flora.
Dissipative coupling-induced phonon lasing
Authors: Zhang Qiankun , Yang Cheng , Sheng Jiteng , Wu Haibin
Published: December 2022

Phonon lasers, as the counterpart of photonic lasers, have been intensively studied in a large variety of systems; however, (all) most of them are based on the directly coherent pumping. Intuitively, dissipation is unfavorable for lasing. Here, we experimentally demonstrate a mechanism of generating phonon lasing from the dissipative coupling in a multimode optomechanical system. By precisely engineering the dissipations of two membranes and tuning the intensity modulation of the cavity light, the two-membrane-in-the-middle system exhibits non-Hermitian characteristics and the cavity-mediated interaction between two nanomechanical resonators becomes purely dissipative. The level attraction and damping repulsion are clearly exhibited as the signature of dissipative coupling. After the exceptional point, a non-Hermitian phase transition, where eigenvalues and the corresponding eigenmodes coalesce, two phonon modes are simultaneously excited into the self-sustained oscillation regime by increasing the interaction strength over a critical value (threshold). In distinct contrast to conventional phonon lasers, the measurement of the second-order phonon correlation reveals the oscillatory and biexponential phases in the nonlasing regime as well as the coherence phase in the lasing regime. Our study provides a method to study phonon lasers in a non-Hermitian open system and could be applied to a wide range of disciplines, including optics, acoustics, and quantum many-body physics.
High acoustic diversity and behavioral complexity of katydids in the Mesozoic soundscape
Authors: Xu Chunpeng , Wang Bo , Wappler Torsten , Chen Jun , Kopylov Dmitry , Fang Yan , Jarzembowski Edmund A. , Zhang Haichun , Engel Michael S.
Published: December 2022

Acoustic communication has played a key role in the evolution of a wide variety of vertebrates and insects. However, the reconstruction of ancient acoustic signals is challenging due to the extreme rarity of fossilized organs. Here, we report the earliest tympanal ears and sound-producing system (stridulatory apparatus) found in exceptionally preserved Mesozoic katydids. We present a database of the stridulatory apparatus and wing morphology of Mesozoic katydids and further calculate their probable singing frequencies and analyze the evolution of their acoustic communication. Our suite of analyses demonstrates that katydids evolved complex acoustic communication including mating signals, intermale communication, and directional hearing, at least by the Middle Jurassic. Additionally, katydids evolved a high diversity of singing frequencies including high-frequency musical calls, accompanied by acoustic niche partitioning at least by the Late Triassic, suggesting that acoustic communication might have been an important driver in the early radiation of these insects. The Early—Middle Jurassic katydid transition from Haglidae- to Prophalangopsidae-dominated faunas coincided with the diversification of derived mammalian clades and improvement of hearing in early mammals, supporting the hypothesis of the acoustic coevolution of mammals and katydids. Our findings not only highlight the ecological significance of insects in the Mesozoic soundscape but also contribute to our understanding of how acoustic communication has influenced animal evolution.
Formation of extramembrane
β
-strands controls dimerization of transmembrane helices in amyloid precursor protein C99
Authors: Pantelopulos George A. , Matsuoka Daisuke , Hutchison James M. , Sanders Charles R. , Sugita Yuji , Straub John E. , Thirumalai D.
Published: December 2022

The 99-residue C-terminal domain of amyloid precursor protein (APP-C99),
precursor to amyloid beta (A
β
), is a transmembrane (TM)
protein containing intrinsically disordered N- and C-terminal extramembrane
domains. Using molecular dynamics (MD) simulations, we show that the structural
ensemble of the C99 monomer is best described in terms of thousands of states.
The C99 monomer has a propensity to form
β
-strand in the
C-terminal extramembrane domain, which explains the slow spin relaxation times
observed in paramagnetic probe NMR experiments. Surprisingly, homodimerization
of C99 not only narrows the conformational ensemble from thousands to a few
states through the formation of metastable
β
-strands in
extramembrane domains but also stabilizes extramembrane
α
-helices.
The extramembrane domain structure is observed to dramatically impact the
homodimerization motif, resulting in the modification of TM domain
conformations. Our study provides an atomic-level structural basis for
communication between the extramembrane domains of the C99 protein and TM
homodimer formation. This finding could serve as a general model for
understanding the influence of disordered extramembrane domains on TM protein
structure.