bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvement of nuclear reaction modeling for the production of 47Sc on natural vanadium targets for medical applications
Authors: Colombi Alessandro , Barbaro Francesca , Canton Luciano , Carante Mario Pietro , Fontana Andrea
Published: April 2022

The proton-induced reaction on natural vanadium targets is studied for the production of the innovative theranostic radionuclide 47Sc as well as of its contaminants, mainly 46Sc. The theoretical excitation functions are calculated using the nuclear reaction code TALYS and are compared with the most recent experimental data. A better agreement between the theoretical curves and the data is achieved with an optimization of the nuclear level density parameters. The obtained improvements represent a useful and important result for accurate evaluations of yields and purities which are needed quantities for subsequent dosimetric studies, in view of the radiopharmaceutical applications of 47Sc. The optimization procedure is explained and shown for 47Sc and 46Sc, and also a comparison among the theoretical and experimental cumulatives is given (for the main contaminant) in addition to an estimation of the production yields for two irradiation conditions for both nuclides.
White Paper – Verbesserung der Versorgungs- und Behandlungsangebote für Menschen mit Sepsis- und Infektionsfolgen
Authors: Fleischmann-Struzek Carolin , Rose Norman , Born Sebastian , Freytag Antje , Ditscheid Bianka , Storch Josephine , Schettler Anna , Schlattmann Peter , Wedekind Lisa , Pletz Mathias W. , Sänger Sylvia , Brunsmann Frank , Oehmichen Frank , Apfelbacher Christian , Drewitz Karl-Philipp , Piedmont Silke , Denke Claudia , Vollmar Horst C. , Schmidt Konrad , Landgraf Irmgard , Bodechtel Ulf , Trumann Arne , Hecker Ruth , Reinhart Konrad , Hartog Christiane S.
Published: April 2022

Hunderttausende Menschen mit Sepsis- und Infektionsfolgen werden derzeit in Deutschland nicht optimal versorgt. Dieses White Paper stellt Maßnahmen zur Verbesserung der Versorgung vor, die von einer multidisziplinären Expertengruppe im Rahmen des Innovationsfonds-Projektes SEPFROK erarbeitet wurden. Eine optimale Versorgung beruht auf 4 Säulen: 1. der sektorenübergreifenden Erfassung der Folgen und einem strukturierten Entlass- und Überleitungsmanagement, 2. einem gezielten Angebot von interdisziplinärer Rehabilitation- und Nachsorge mit struktureller Unterstützung, 3. der Stärkung der spezifischen Gesundheitskompetenz von Betroffenen und Angehörigen und 4. der Intensivierung der Forschung zu Ursachen, Prävention und Therapie der Folgen. Hierfür müssen entsprechende sektorenübergreifende Versorgungsstrukturen und sozialrechtliche Rahmenbedingungen geschaffen werden.
Helical Amide Derivatives: Synthesis by Insertion of Aliphatic ­Primary Amines into Benzo-Fused 2,2′-Diphenoquinones and Dia­stereomeric Resolution
Authors: Hossain Md. Sharif , Karikomi Michinori , Akter Mahmuda , Kurihara Takashi , Iimura Ken-ichi
Published: April 2022

We have developed a method for synthesizing novel helical amide derivatives. Nucleophilic primary amines were inserted into benzo-fused 2,2′-biphenoquinones to form helical amides containing seven-membered rings. When optically pure primary amines were used in this reaction, a mixture of two amide diastereoisomers was obtained and separated into diastereomerically pure products by high-performance liquid chromatography. In contrast, the reaction of enantiomerically pure benzo-fused 2,2′-biphenoquinones with achiral aliphatic primary amines afforded enantiomerically pure helical amides with stereospecificity and retention of configuration.
Higher Pelvic Incidence Was Associated with a Higher Risk of Sagittal Malposition of Femoral Component and Poor Outcomes of Primary Total Knee Arthroplasty: A Retrospective Cohort Analysis
Authors: Li Hongyi , Zhu Fei , Liao Shufen , Wang Xiangjiang , Zhong Yanlin , Wen Xingzhao , Zhao Xiaoyi , Liao Weiming , Zhang Zhiqi
Published: April 2022

Spine–pelvis–lower extremity sagittal alignment is regarded as a global sagittal balance. Currently, there are few studies evaluating the pelvic and femoral sagittal alignment during total knee arthroplasty (TKA). This retrospective study aims to elucidate how pelvic and femoral sagittal alignment affect clinical outcomes of primary TKA for osteoarthritis (OA) and determine the proper range of femoral sagittal alignment. Patient-reported outcome measures (PROMs), including the Knee Society Score (KSS), Western Ontario and McMaster Universities (WOMAC), and patient satisfaction scores, and clinician-reported outcomes (CROs), including range of motion (ROM) and pelvic and femoral sagittal parameters, of 67 cases were evaluated (89 knees) before and 1 year after TKA. The angle between the distal femur anterior cortex line and flange of the femoral component (FC) was defined as the α angle. Correlations between the α angle and PROM and CRO were investigated using multivariate and secondary regression analyses. Patients were further divided into four cohorts (A, B, C, and D) according to the α angle, and comparisons of their postoperative PROM and ROM scores were performed. Postoperative PROM and ROM scores improved significantly compared with the preoperative scores (p < 0.01). Only the α angle was significantly associated with postoperative knee extension among all PROM and CRO indexes (p = 0.001). Secondary regression demonstrated a convex upward function, and the scores were the highest at α angles of 0.57, 0.96, and −1.42 degrees for postoperative KSS, satisfaction, and range of knee extension, respectively (p < 0.01). However, the concave upward degree was the lowest at an α angle of 0.33 degrees for pelvic incidence (p < 0.001). Bonferroni's paired comparisons indicated that postoperative KSS and satisfaction of the cohort B (0 degrees ≤ α angle ≤ 3 degrees) were better than those of other cohorts (p < 0.0125). The results indicate that surgeons should pay more attention to the sagittal alignment of FC in patients with increased pelvic incidence, the distal femoral anterior cortex is recommended as an anatomic landmark, and 0 to 3 degrees might be “safe zones” of the sagittal flexion of FC in TKA. This study reflects the level of evidence III.
Impact of Liver Cirrhosis on Bone Metabolism
Authors: Abdalbary Mohamed , Sobh Mahmoud , Abdelsalam Mostafa , Mohamed Amr El-Husseini
Published: April 2022

Bone loss is an early and major problem in cirrhotic patients. The majority of cirrhotic patients demonstrate evidence of hepatic osteodystrophy (HOD). This includes decreased bone volume, turnover abnormalities, and rarely mineralization defects. Moreover, the degree of bone disease usually correlates with the severity of liver dysfunction. The mechanism of HOD is multifactorial. Vitamin D insufficiency/deficiency, secondary hyperparathyroidism, hypogonadism, inhibitors of bone formation, and mediators/promoters of bone resorption are frequent findings and essential coplayers in HOD. Early and proper identification of HOD is challenging. DXA is the most widely used tool; however, it has fundamental limitations. Bone turnover biomarkers are used to understand the mechanism of bone loss. Bone biopsy with histomorphometry is the gold standard to evaluate bone structure. The evidence for the effectiveness of nonpharmacological and pharmacological management of HOD is limited. Adequate nutrition, weight-bearing exercise, smoking cessation, and limitation of alcohol consumption improve bone health and quality of life. The use of antiresorptive therapies prevents bone loss particularly in patients with high bone turnover. However, osteoanabolics are essential in patients with low bone turnover. Herein, we are discussing the magnitude of the problem, pathogenesis, diagnosis of HOD, and various interventions to improve bone health in cirrhotic patients.
Dural Sealants Do Not Reduce Postoperative Cerebrospinal Fluid Leak after Endoscopic Endonasal Skull Base Surgery
Authors: McDowell Michael M. , Jacobs Rachel C. , Valappil Benita , Abou-Al-Shaar Hussam , Zenonos Georgios A. , Wang Eric W. , Snyderman Carl H. , Gardner Paul A.
Published: April 2022

Introduction The application of cranial tissue sealants to assist with postoperative closure is widespread, but data are lacking regarding its utility in endoscopic endonasal surgery (EEA). A prospective study was conducted to assess the effect of sealant usage on postoperative cerebrospinal fluid (CSF) leak rate following standard reconstruction.

Methods A prospective trial of sealant usage after endoscopic endonasal skull base surgery was performed from May 2016 to June 2019 at a tertiary referral cranial base center. This study enrolled 300 consecutive adult and pediatric patients with skull base pathology who underwent EES in which an intraoperative CSF leak occurred. Patients were sequentially stratified into equally sized groups who did or did not receive sealant as part of their reconstruction.

Results Three hundred consecutive adult and pediatric patients were enrolled in the study and had a confirmed intraoperative CSF leak. The intervention cohort with sealant (first 150 patients) had 21 postoperative CSF leaks (14% rate) compared with 9 postoperative CSF leaks (6% rate) in the control group without sealant (p = 0.02). On multivariate analysis, sealant usage was associated with a higher rate of postoperative CSF leak (odds ratio [OR] = 2.7; p = 0.025). Male gender (OR = 2.4; p = 0.04) and high-flow intraoperative CSF leak (OR = 3.1; p = 0.038) were also found to be associated with postoperative CSF leak.

Conclusion Among all patients undergoing EES with an intraoperative CSF leak, the addition of sealant to standard closure techniques did not reduce the rate of postoperative CSF leaks.
Impedance matching system using triple liquid stub tuners for high-power ion cyclotron resonance heating in EAST tokamak
Authors: Liu L. N. , Wang L. , Yuan S. , Mao Y. Z. , Saito K. , Zhang X. J. , Qin C. M. , Liang Q. C. , Long X. Y. , Zhao Y. P. , Cheng Y. , Zhang W. , Yang H. , Zhu G. H. , Zhang K. , Ping L. L. , Ai L. , Guo Y. Y. , Wang G. X. , Zheng W. M. , Gao X. , Lin X. D. , Wu M. Q.
Published: April 2022

Ion cyclotron resonance heating (ICRH), one of the main auxiliary methods, for high-power and long-pulse plasma heating had been developed in Experimental Advanced Superconducting Tokamak (EAST). An impedance matching system, one important part of ICRH, had been developed for high-power injection and transmitter protection by reducing the reflected power from the antenna. The input impedance in the outlet of the stub tuner can be measured by voltage–current probes installed on the coaxial transmission line between the antenna and triple liquid stub tuners, and the optimum liquid levels in the stub tuners can be calculated based on the input impedance. The calculation and adjustment process of the optimum liquid levels are described comprehensively in this article. Finally, impedance matching had been achieved between two shots during EAST experiments. In the near future, a real-time impedance matching system will be developed to prevent large variations of the ICRH antenna impedance and achieve steady-state and long-pulse operation with the ICRH system.
Bandgap tuning, high electrical conductivity, and room-temperature ferromagnetism in La- and V-doped SrSnO3 epitaxial films
Authors: Zhao Li , Li Haozhe , Lv Kai , Wang Haifeng , Liu Qinzhuang
Published: April 2022

In this study, La- and V-doped SrSnO3 epitaxial films were fabricated via pulsed laser deposition, and the effects of doping on the structure and physical properties of films were systematically investigated. Detailed x-ray diffraction characterization demonstrates that the lattice parameters of V-doped SrSnO3 (SrSn1−xVxO3, x = 0–1, SSVO) films decrease gradually as the V content increases. The optical bandgap first increases from 4.43 to 4.56 eV and then decreases to 3.31 eV with the increasing V content. Density functional theory calculations indicate that the strong hybridization between Sn 5s and V 3d orbitals causes an initial expansion of the bandgap. Doping SSVO films with 5% La greatly improves the electrical conductivity. Hall-effect measurements show that the (La0.05Sr0.95)VO3 film has the lowest room-temperature resistivity of 0.05 mΩ cm and correspondingly the largest carrier density of 1.79 × 1022 cm−3. Ferromagnetism in SrSn1−xVxO3 films is highly dependent on V concentration at room-temperature, and the origin of ferromagnetism may be explained by the bound magnetic polaron model.
Radiative relaxation in isolated large carbon clusters: Vibrational emission versus recurrent fluorescence
Authors: Lacinbala O. , Calvo F. , Dubosq C. , Falvo C. , Parneix P. , Rapacioli M. , Simon A. , Pino T.
Published: April 2022

Recurrent fluorescence (RF) from isolated carbon clusters containing between 24 and 60 atoms is theoretically investigated as a function of internal energy, cluster size, and structural features. The vibrational relaxation kinetics and the associated IR emission spectra are determined by means of a Monte Carlo approach with vibrational density of states computed in the harmonic approximation. RF is generally found to be highly competitive with vibrational emission. The behaviors predicted for clusters of various sizes and archetypal structures indicate that the IR emission spectra are strongly influenced by RF, an energy gap law being obtained for the evolution of the RF rate constant depending on the electronic excitation state. The present results are relevant to the photophysics of the interstellar medium and could contribute to elucidating the carriers of the extended red emission bands and the continuum emission lying below the aromatic infrared bands believed to originate from mixed aromatic–aliphatic compounds.
Tuning of the Dzyaloshinskii–Moriya interaction by He+ ion irradiation
Authors: Nembach Hans T. , Jué Emilie , Poetzger Kay , Fassbender Juergen , Silva Thomas J. , Shaw Justin M.
Published: April 2022

We studied the impact of He+ irradiation on the Dzyaloshinskii–Moriya interaction (DMI) in Ta/Co20Fe60B20/Pt/MgO samples. We found that irradiation of 40 keV He+ ions increases the DMI by approximately 20% for fluences up to 2 × 1016 ions/cm2 before it decreases for higher fluence values. In contrast, the interfacial anisotropy shows a distinctly different fluence dependence. To better understand the impact of the ion irradiation on the Ta and Pt interfaces with the Co20Fe60B20 layer, we carried out Monte-Carlo simulations, which showed an expected increase in disorder at the interfaces. A moderate increase in disorder increases the total number of triplets for the three-site exchange mechanism and consequently increases the DMI. Our results demonstrate the significance of disorder for the total DMI.
Simulation of atrial fibrillation in a non-ohmic propagation model with dynamic gap junctions
Authors: Saliani Ariane , Biswas Subhamoy , Jacquemet Vincent
Published: April 2022

Gap junctions exhibit nonlinear electrical properties that have been hypothesized to be relevant to arrhythmogenicity in a structurally remodeled tissue. Large-scale implementation of gap junction dynamics in 3D propagation models remains challenging. We aim to quantify the impact of nonlinear diffusion during episodes of arrhythmias simulated in a left atrial model. Homogenization of conduction properties in the presence of nonlinear gap junctions was performed by generalizing a previously developed mathematical framework. A monodomain model was solved in which conductivities were time-varying and depended on transjunctional potentials. Gap junction conductances were derived from a simplified Vogel–Weingart model with first-order gating and adjustable time constant. A bilayer interconnected cable model of the left atrium with 100 μm resolution was used. The diffusion matrix was recomputed at each time step according to the state of the gap junctions. Sinus rhythm and atrial fibrillation episodes were simulated in remodeled tissue substrates. Slow conduction was induced by reduced coupling and by diffuse or stringy fibrosis. Simulations starting from the same initial conditions were repeated with linear and nonlinear gap junctions. The discrepancy in activation times between the linear and nonlinear diffusion models was quantified. The results largely validated the linear approximation for conduction velocities >20 cm/s. In very slow conduction substrates, the discrepancy accumulated over time during atrial fibrillation, eventually leading to qualitative differences in propagation patterns, while keeping the descriptive statistics, such as cycle lengths, unchanged. The discrepancy growth rate was increased by impaired conduction, fibrosis, conduction heterogeneity, lateral uncoupling, fast gap junction time constant, and steeper action potential duration restitution.
A perspective on sustainable luminescent solar concentrators
Authors: Hernández-Rodríguez M. A. , Correia S. F. H. , Ferreira R. A. S. , Carlos L. D.
Published: April 2022

The luminescent solar concentrator (LSC) concept appeared almost forty years ago, as a solution to overcome the limitations related to photovoltaic cell efficiency. Nowadays, they are seen as a promising approach to integrate photovoltaic elements into the built environment, in an invisible way and without detrimental effects to the aesthetics of the building or the quality of life of the inhabitants. LSCs are devices comprising a transparent matrix embedding optically active centers that absorb the incident radiation, which is re-emitted at a specific wavelength and transferred by total internal reflection to photovoltaic cells located at the edges of the matrix. During the last few decades, several optically active materials have been tested for LSCs in an endless quest for the most efficient device. Nowadays, one of the world's major concerns is the environmental impact of our choices. Thus, the present and future path for LSCs must include the search for nature-friendly materials, with little environmental impact, and, in this sense, this Perspective offers a general overview of the potential of environmentally-friendly materials for LSCs.
Nanosecond ultralow power spin orbit torque magnetization switching driven by BiSb topological insulator
Authors: Khang Nguyen Huynh Duy , Shirokura Takanori , Fan Tuo , Takahashi Mao , Nakatani Naoki , Kato Daisuke , Miyamoto Yasuyoshi , Hai Pham Nam
Published: April 2022

Topological insulators (TIs) are promising for spin–orbit torque (SOT) switching thanks to their giant spin Hall angle. SOT switching using TIs has been studied so far in the thermal activation regime by direct currents or relatively long pulse currents (≥10 ns). In this work, we studied SOT magnetization switching of (Pt/Co) multilayers with strong perpendicular magnetic anisotropy by the BiSb topological insulator in both thermal activation and fast switching regime with pulse width down to 1 ns. We reveal that the zero-Kelvin threshold switching current density Jth0BiSb is 2.5 × 106 and 4.1 × 106 A/cm2 for the thermal activation regime and fast switching regime in a 800 nm-wide Hall bar device via domain wall depining. From time-resolved measurements using 1 ns pulses, we find that the domain wall velocity is 430–470 m/s at JBiSb = 1.6 × 107–1.7 × 107 A/cm2. Our work demonstrates the potential of the BiSb thin film for ultralow power and fast operation of SOT-based spintronic devices.
Influence of an upstream hydrofoil on the acoustic signature of a propeller
Authors: Posa A. , Felli M. , Broglia R.
Published: April 2022

The acoustic analogy is adopted to reconstruct the sound generated by a system consisting of a hydrofoil and a downstream propeller. The data from high-fidelity large-eddy simulations with the hydrofoil at angles of incidence of 0°, 10°, and 20° were generated using a cylindrical grid consisting of 1.7 × 109 points. The results of the analysis demonstrate the following: (i) the strong influence by the incidence of the hydrofoil on the acoustic signature of the system; (ii) the leading role of the non-linear component of sound at small radial coordinates in the vicinity of the wake, especially moving away from the propeller plane; (iii) the leading role of the linear component of sound from the surface of the propeller moving away along the radial direction; (iv) the importance of the shear between the wakes shed by the hydrofoil and the propeller in accelerating the process of instability of the coherent structures and reinforcing the non-linear sources of sound; and (v) the strong, complex directivity of sound at small radial coordinates, as a consequence of the interaction between the wakes from the hydrofoil and the propeller.
Improved electric contact of recessed source and drain electrodes for sol–gel-based thin-film transistors consisting of amorphous ZrO2 and IGZO fabricated by microwave-annealing
Authors: Park Sang-Joon , Ha Tae-Jun
Published: April 2022

We investigate the effects of recessed source/drain (S/D) electrodes on the device performance of microwave-induced metal-oxide thin-film transistors (oxide-TFTs) by analyzing their contact resistances. High-performance top-gate-bottom-contact oxide-TFTs consisting of sol–gel-based high-k zirconium dioxide dielectric (ZrO2) and indium-gallium-zinc oxide (IGZO) semiconducting films were developed by employing microwave annealing. Vibration energy induced microwave annealing even at a low temperature (∼120 °C) with a short process time (10 min), which is sufficient to form dense metal–oxygen bonding while suppressing oxygen vacancies as defect states, resulted in high-quality sol–gel-based amorphous ZrO2 and IGZO films. The low-voltage operating oxide-TFTs with recessed S/D electrodes exhibited higher field-effect mobility (∼7.0 cm2 V−1 s−1) than those with elevated S/D electrodes (∼0.15 cm2 V−1 s−1). This result is attributed to the conformable deposition of the channel layer on the planar surface of S/D electrodes, leading to the improved interfacial characteristics. Relatively low effective contact resistance (∼79.7 Ω cm), which was extrapolated from a plot of the width-normalized resistance as a function of the channel length using a transmission line method, in oxide-TFTs with recessed S/D electrodes, is compared to that (∼1480.6 Ω cm) of elevated S/D electrodes. This was in good agreement with the Ohmic contact behavior contact where the low charge injection barrier improved charge transport.
Optimal control of growth of instabilities in Taylor–Couette flow
Authors: Dandelia Harvansh , Kant Ravi , Narayanan Vinod
Published: April 2022

The present work aims to achieve optimal control of instabilities in a standard Taylor–Couette flow. The motivation of the present study is to reduce the disturbance growth and delay the transition process to turbulence. We numerically employ control using a stability modifier, namely, wall transpiration. In the non-modal stability framework, we form a state-space model employing control actuation by means of periodic suction/blowing of fluid from the walls. The study is conducted for two cases of flow rotations: (i) counter-rotating cylinders and (ii) the stationary outer cylinder with inner cylinder rotating. The parametric study was performed with varying radii ratios, Reynolds numbers (Re), axial (α), and azimuthal (n) wavenumbers. The time evolution of governing equation is written in terms of perturbation velocities in radial (r) and azimuthal (θ) directions. The optimal feedback control is obtained using a linear quadratic regulator controller and feed backed to the system to reduce the maximum optimal growth of the instabilities in the flow. The perturbation kinetic energy is taken as the measure of the amplification of disturbances and used as the cost function to be minimized. We use Chebyshev spectral collocation method to discretize the equations and variational method to calculate the optimal growth. We studied four different parametric cases of radii ratios (η=r1r2= 0.1, 0.25, 0.5, 0.75), with angular velocity (Ω2Ω1) ratio fixed as μ=−1 and μ = 0. We choose the subcritical wavenumbers that led to a maximum transient energy growth corresponding to a Reynolds number ≈ 0.65 times the critical Reynolds number for the case of counter-rotation. For the case of the stationary outer cylinder, we showed the effect of the control in the modal analysis framework. The presented control technique resulted in a maximum of 72% reduction in the growth rate and the typical growth of perturbation energy.
Revealing protein reactions using transient grating method: Photo-induced heating, volume change, and diffusion change
Authors: Terazima Masahide
Published: April 2022

The transient grating (TG) method, which is one of the photothermal techniques, can enable sensitive detection of thermal energy with high temporal resolution based on changes in the refractive index of a material. In addition to thermal energy, the TG method can also detect any changes that affect the refractive index, such as changes in the partial molar volume and in the absorption spectrum far from the probe wavelength. In this Perspective, recent studies on chemical reaction dynamics of proteins using the TG method are reviewed and discussed. To reveal the reaction schemes of proteins, it is particularly important to detect dynamics that cannot be detected by optical spectroscopy (spectrally silent dynamics), such as enthalpy changes, conformational changes, and changes in intermolecular interactions (protein–water, protein–protein, protein–lipids, and protein–DNA). The TG method is appropriate and powerful for such applications. Spectrally silent dynamics have clearly been observed by monitoring time-resolved diffusion and volume changes. Furthermore, the impact of the structural fluctuation of proteins on their reactivity has been successfully demonstrated by monitoring the thermal expansion and compressibility changes of short-lived intermediates. For expansion of the TG application to non-photochemical reactions, one attempt using the stopped flow-TG technique is described. Future possible applications of the TG method are suggested.
Large-scale flexible membrane with resonant silicon nanowires for infrared visualization via efficient third harmonic generation
Authors: Nikolaeva Anna , Mastalieva Viktoria , Gudovskikh Alexander S. , Morozov Ivan A. , Fedorov Vladimir V. , Petrov Mihail , Neplokh Vladimir , Mukhin Ivan S. , Makarov Sergey V.
Published: April 2022

Nonlinear harmonic generation in nanostructures is one of the key topics in nanophotonics, as it allows infrared-to-visible light conversion at the nanoscale. Indeed, various nanophotonic designs have been developed to demonstrate high efficiencies for third harmonic generation (THG). However, fabrication approaches for these designs usually involve high-cost lithography-based technological steps. This work reports on the efficient THG in a free-standing Si nanowire array encapsulated into a flexible polymer membrane. High nonlinearity of Si material χ1111(3)≈2.62×10−19m2/V2 and light coupling with optical resonances in the nanowires yield a strong third-harmonic signal and efficient infrared (1200–2000 nm) to visible (400–666 nm) upconversion. The fabricated membranes demonstrate high flexibility and transparency, which make them convenient to use as infrared light visualizers.
Wavelet analysis of high-speed transition and turbulence over a flat surface
Authors: Khujadze George , Drikakis Dimitris , Ritos Konstantinos , Kokkinakis Ioannis W. , Spottswood S. Michael
Published: April 2022

This paper presents a study of high speed boundary layers using the wavelet method. We analyze direct numerical simulation data for high-speed, compressible transitional, and turbulent boundary layer flows using orthogonal anisotropic wavelets. The wavelet-based method of extraction of coherent structures is applied to the flow vorticity field, decomposed into coherent and incoherent contributions using thresholding of the wavelet coefficients. We show that the coherent parts of the flow, enstrophy spectra, are close to the statistics of the total flow, and the energy of the incoherent, noise-like background flow is equidistributed. Furthermore, we investigate the distribution of the incoherent vorticity in the transition and turbulent regions and examine the correlation with the near-wall pressure fluctuations. The results of our analysis suggest that the incoherent vorticity part is not a random “noise” and correlates with the actual noise emanating from inside the boundary layer. This could have implications regarding our understanding of the physics of compressible boundary layers and the development of engineering models.
Tunable spectral squeezers based on monolithically integrated diamond Raman resonators
Authors: Granados E. , Stoikos G. , Echarri D. T. , Chrysalidis K. , Fedosseev V. N. , Granados C. , Leask V. , Marsh B. A. , Mildren R. P.
Published: April 2022

We report on the generation and tuning of single-frequency laser light in a monolithic Fabry–Pérot diamond Raman resonator operating in the visible spectral range. The device was capable of squeezing the linewidth of a broad multi-mode nanosecond pump laser (Δνp= 7.2 ± 0.9 GHz at λp= 450 nm) to a nearly Fourier-limited single axial mode Stokes pulse (ΔνS= 114 ± 20 MHz at λS= 479 nm). The tuning was achieved by precise adjustment of the resonator temperature, with a measured frequency-temperature tuning slope of ∂ν0/∂T≈ −3 GHz/K, and a temperature dependence of the first-order Raman phonon line of ∂νR/∂T≈ +0.23 GHz/K. The Stokes center frequency was tuned continuously for over 20 GHz (more than twice the free spectral range of the resonator), which, in combination with the broad Ti:Sapphire laser spectral tunability, enables the production of Fourier-limited pulses in the 400–500 nm spectral range. The Stokes center-frequency fluctuations were 52 MHz (RMS) when the temperature of the resonator was actively stabilized. Moreover, the conversion efficiency was up to 30%, yielding an overall power spectral density enhancement of >25× from pump to Stokes pulse.
Generation mechanism of a new type of unburnt gas pocket and its influences on the detonation-wave/boundary-layer interaction
Authors: Wang Yuqi , Liang Jianhan , Cai Xiaodong , Mahmoudi Yasser
Published: April 2022

This work studies numerically the generation mechanism of a new type of unburnt gas pocket and its effects on the characteristics of detonation-wave/boundary-layer interaction in supersonic flows. Results show that this new type of unburnt pocket is generated due to a local re-ignition of preheated gas behind the separated oblique shocks, unlike the traditional unburnt pockets generated due to the longitudinal instability of the detonation front. The chemical energy released by the new unburnt pocket in the supersonic area is found to be blocked by the shear layer and is unfavorable for the self-sustaining propagation of the detonation wave.
Turbulence compressibility reduction with helicity
Authors: Yang Yan , Zhu Jian-Zhou
Published: April 2022

A numerical test of isotropic turbulence compressibility reduction with helicity in a cyclic box is performed. The ratios of compressibility-relevant-mode spectra over those of kinetic energy present power laws at large wavenumbers in the dissipation range, indicating a common difference of 11/15 in the exponents of the algebraic prefactor of the nonhelical power spectra over those of helical ones. Our results being not derived from the shapes of the spectra themselves, the implied information about the helicity effect on the complex singularities of the discretized dynamical system can be of reasonable value for insight of the Navier–Stokes equation, though the high-order finite difference scheme used for computation may not be as accurate in the dissipation range as the state-of-the-art of incompressible turbulence with the pseudo-spectral method. Possible applications in controlling flows, for the purpose of, say, decreasing turbulence noise, are also discussed according to the spectral fluctuations.
Low-frequency anharmonic couplings in bromoform revealed from 2D Raman-THz spectroscopy: From the liquid to the crystalline phase
Authors: Mousavi Seyyed Jabbar , Berger Arian , Hamm Peter , Shalit Andrey
Published: April 2022

Two-dimensional (2D) Raman-THz spectroscopy in the frequency of up to 7 THz has been applied to study the crystalline β-phase of bromoform (CHBr3). As for liquid CHBr3, cross peaks are observed, which, however, sharpen up in the crystalline sample and split into assignable sub-contributions. In the Raman dimension, the frequency positions of these cross peaks coincide with the intramolecular bending modes of the CHBr3 molecules and in the THz dimension with the IR-active lattice modes of the crystal. This work expands the applicability of this new 2D spectroscopic technique to solid samples at cryogenic temperatures. Furthermore, it provides new experimental evidence that the cross peaks, indeed, originate from the coupling between intra- and intermolecular vibrational modes.
Simonachne, a new genus for Australia segregated from Ancistrachne s.l. (Poaceae : Panicoideae : Paniceae) and a new subtribe Cleistochloinae
Authors: Thompson E. J.
Published: April 2022

A new genus, Simonachne E.J.Thomps. is described and Ancistrachne maidenii (A.A.Ham.) Vickery is transferred to it as Simonachne maidenii (A.A.Ham.) E.J.Thomps. The new subtribe Cleistochloinae E.J.Thomps. is described and is composed of four genera, Calyptochloa, Cleistochloa, Dimorphochloa and Simonachne, united by distinctive morphology that is associated with reproductive dimorphism. Phenetic analyses were used to examine the similarities of taxa and to test the consistency of results with variation in analysis inputs. Input variations included the dataset in terms of composition of the samples and morphological characters, and the cluster analysis algorithms, viz. classification, ordination and association measure. A baseline dataset was used for comparison of results and comprised 24 samples and 161 characters relating to anatomy, micro- and macromorphology of spikelets, leaves and fertile culms. Three major clusters were resolved, Cleistochloinae (‘the cleistogamy group’), Neurachninae in its original sense, and a cluster referred to as the ‘paniculate inflorescence group’ composed of Ancistrachne s.s., Entolasia and Panicum s.s. The results were congruent with a recent phylogenetic study that showed that Ancistrachne s.l., Cleistochloa s.l. and Dimorphochloa s.l. were not monophyletic. The process provided an array of morphological characters for descriptions of species and for distinguishing taxa at multiple ranks in natural groups, components of alpha and beta taxonomy respectively.
Review of recent progress, challenges, and prospects of 2D materials-based short wavelength infrared photodetectors
Authors: Pinki Yadav  , Dewan Sheetal , Mishra Rahul , Das Samaresh
Published: April 2022

The interest in 2D layered materials based short wavelength infrared (SWIR) photodetectors (PDs) has escalated over the years with the introduction of new 2D materials showing intriguing photoresponse characteristics in the IR region. Two-dimensional materials with their mechanical flexibility, bandgap tunability, ease in exfoliation and thickness dependent optical properties have shown potential to surpass the performance of conventional, cryogenically operated semiconducting PDs. To date, a significant number of PDs have been reported using layered materials in various configurations, which have attracted the interest of research community towards scalable 2D-PDs. This review article aims to address current state-of-art SWIR PDs based on layered materials and the underlying physics. The article gives an insight into the various photodetection schemes and important figures of merit for the evaluation of PDs. The 2D materials frequently employed for designing SWIR PDs and their important characteristics are discussed in detail, with special emphasis on their photodetection range. Further, a comprehensive review of the 2D SWIR PDs based on different device structures is included, followed by a discussion on the major challenges currently prevalent in 2D SWIR PDs. Finally, the promising future prospects of 2D SWIR PDs and their important applications are described.
The distribution of F-containing species in atmospheric nanosecond He/CF4 plasma with downstream dielectric material
Authors: Liu Jie , Wang Lijun , Zhang Runming , Lian Zhuoxi
Published: April 2022

A two-dimensional self-consistent model has been established in order to investigate the distribution of F-containing species in He/CF4 atmospheric pressure plasma jet and the effect of CF4 concentration on the reactive F-containing species. A portion of electron energy is consumed whenever an F is ionized from the CF4, resulting that the average densities of

CF

4
+

,

CF

2
+

and CF+ decrease sequentially. The density of

CF

3
+

is greater than

CF

4
+

density due to Penning ionization of He* with CF4 and He+ + CF4 →

CF

3
+

+ F + He. In the case of He + 0.5% CF4 at 200 ns, the electron impact reactions mainly concentrate on the streamer head on the dielectric surface. The Penning ionization of He* with CF4 dominates in the region of 0 < r < 2.2 mm benefits from long-lived He* of high density and the high concentration CF4 in this region. As gas flow gradually mixes with ambient air (r > 2.2 mm), the Penning ionization of metastable He with N2 and O2 dominates in this area. As the CF4 concentration increases from 0.1% to 1%, the densities of F-containing positive ions all increase significantly. CF3, F and F2 also show the upward trend while there is little change in the spatial densities of CF2 and CF. The F-containing neutral species flux benefits from two factors: the diffusion and the conversion of positive ions. In the case of 0.1% CF4, due to the low density of

CF

2
+

, CF+ and F+ and the diffusion of F, the F flux for is consistent with CF2 and is greater than CF. However, when CF4 concentration exceeds 0.5%, the concentration of

CF

3
+

,

CF

2
+

and CF+ are much higher than F+. The quenching of positive ions dominates on the dielectric surface in the case of 0.5% and 1% CF4, resulting that the flux of F is lower than that of CF2 and CF.
Understanding the kinetic anisotropy of the soft-sphere bcc crystal–melt interfaces
Authors: Wang Yashen , Liang Zun , Zhang Xin , Lu Wenliang , Yu Zhiyong , Ma Xiangming , Liang Hongtao , Yang Yang
Published: April 2022

By employing the non-equilibrium molecular dynamics (MD) simulations and the time-dependent Ginzburg–Landau (TDGL) theory for the solidification kinetics, we predict the kinetic coefficients for the bcc(100), (110), and (111) CMIs of the soft-spheres, which are modeled with the inverse-power repulsive potential, and compare with the previous reported data of the bcc Fe system. We confirm a universal-like behavior of the spatial integrations of the (density wave amplitudes) Ginzburg–Landau order parameter square-gradient for the bcc CMI systems. The TDGL predictions of the kinetic anisotropies for bcc soft-sphere and bcc Fe CMI systems are identical; both agree well with the MD measurement for the soft-sphere system but differ strongly with the MD measurement for the Fe system. This finding implies that the current TDGL theory reflects a preference of presenting the generic anisotropy relationship due to the interfacial particle packings but lacks the contribution parameter which addresses the specificities in the kinetic anisotropies owing to the particle–particle interactions. A hypothesis that the density relaxation times for the interface melt phases to be anisotropic and material-dependent is then proposed.
Ab initio calculations of spin-nonconserving exciton–phonon scattering in monolayer transition metal dichalcogenides
Authors: Zhang Xiao-Wei , Cao Ting
Published: April 2022

We investigate the spin-nonconserving relaxation channel of excitons by their couplings with phonons in two-dimensional transition metal dichalcogenides using ab initio approaches. Combining GW-Bethe–Salpeter equation method and density functional perturbation theory, we calculate the electron–phonon and exciton–phonon coupling matrix elements for the spin-flip scattering in monolayer WSe2, and further analyze the microscopic mechanisms influencing these scattering strengths. We find that phonons could produce effective in-plane magnetic fields which flip spin of excitons, giving rise to relaxation channels complimentary to the spin-conserving relaxation. Finally, we calculate temperature-dependent spin-flip exciton–phonon relaxation times. Our method and analysis can be generalized to study other two-dimensional materials and would stimulate experimental measurements of spin-flip exciton relaxation dynamics.
Thermal conductivity temperature dependence of water confined in nanoporous silicon
Authors: Wang Xiaorui , Gonçalves William , Lacroix David , Isaiev Mykola , Gomès Séverine , Termentzidis Konstantinos
Published: April 2022

Recently, it has been shown that high density nanoconfined water was the reason of the important enhancement of the effective thermal conductivity up to a factor of 50% of a nanoporous silicon filled with water. In this work, using molecular dynamics simulations, we further investigate the role of the temperature T (from 285 to 360 K) on the thermal conductivity enhancement of nanohybrid porous silicon and water system. Furthermore, by studying and analysing several structural and dynamical parameters of the nanoconfined water, we give physical insights of the observed phenomena. Upon increasing the temperature of the system, the thermal conductivity of the hybrid system increases reaching a maximum for T = 300 K. With this article, we prove the existence of new heat flux channels between a solid matrix and a nanoconfined liquid, with clear signatures both in the radial distribution function, mean square displacements, water molecules orientation, hydrogen bond networks and phonon density of states.
Energy balance, efficiency and operational limits of the dynamo type flux pump
Authors: Morandi A , Russo G , Fabbri M , Soldati L
Published: April 2022

In rotating flux pumps, a rectified voltage, with non-zero DC component, is obtained at the terminals due to the combined effect of the distributed AC electromotive force, produced by one or more permanent magnets in circular motion and the non-linear resistivity of the superconductor. Overcritical currents are continuously induced in the tape during operation, giving rise to the DC voltage and producing, at the same time, dissipation. In this paper, the energy behavior of the flux pump is numerically investigated. It is shown that induced currents interact with the rotating magnet(s), producing a resistant torque that is little affected by the output current of the flux pump. Due to this interaction mechanism, a significant part of the mechanical power supplied to the rotor is converted into Joule heating within the tape. The paper also explores the operational limits of the flux pump, showing that the generator operation, involving an electric power delivered to the load combined with a mechanical power supplied to the rotor, can only be achieved in a restricted range of current and voltage at the terminals and that the maximum power transfer and efficiency are reached at the middle of the generator range. Under no conditions, the mechanical torque produced on the rotor can be reversed, reaching the motor mode involving an electric power absorbed at the terminals combined with a mechanical power produced on the rotor. A revised equivalent circuit comprising, besides the effective resistance reported in the literature, a further intrinsic resistance is proposed in the paper for taking all the dissipation mechanisms into account. It is shown that this equivalent circuit can predict the energization of an RL load both concerning the final steady values and the full time-domain behavior of the current (including ripples).
Disorder-induced 2D superconductivity in a NbTiN film grown on Si by ultrahigh-vacuum magneton sputtering
Authors: Chen Sheng-Zong , Yang Jing-Wei , Peng Tzu-Yu , Chu Yu-Cheng , Yeh Ching-Chen , Hu I-Fan , Mhatre Swapnil , Lu Yu-Jung , Liang Chi-Te
Published: April 2022

We report on the growth and characterization of a niobium titanium nitride (NbTiN) film on a Si substrate prepared by ultrahigh vacuum sputtering. We show that the superconducting transition temperature is lower than those of high-quality NbTiN films. Interestingly, even though the zero-temperature Ginzburg-Landau coherence length (=9.77 nm) is significantly shorter than the film thickness (=86 nm), we are still able to observe the Berezinskii-Kosterlitz-Thouless-like transition, indicating the two-dimensional (2D) signature of our three-dimensional (3D) sample. We propose that the mechanism of hidden 2D superconducting property is similar to the recently reported results of the disordered induced 3D to 2D superconductor transition. We suggest further theoretical work is required for studying our new experimental results.
A novel lattice model integrating the cooperative deviation of density and optimal flux under V2X environment
Authors: Peng Guang-Han , Luo Chun-Li , Zhao Hong-Zhuan , Tan Hui-Li
Published: April 2022

A novel lattice hydrodynamic model is proposed by integrating the cooperative deviation of density and optimal flux under vehicle to X (V2X) environment. According to the theoretical analysis, the stability conditions and the mKdV equations affected by the cooperative deviation of traffic information are explored. And the density wave, hysteresis loop and energy consumption of the traffic flow have been investigated via numerical simulation. The results indicate that the cooperative deviation of density and optimal flux can effectively alleviate the traffic congestion. More importantly, our new consideration can reduce fuel consumption and exhaust emission under the V2X environment.
Non-volatile multi-state magnetic domain transformation in a Hall balance
Authors: Gao Yang , Zhang Jingyan , Dou Pengwei , Li Zhuolin , Zhu Zhaozhao , Guo Yaqin , Hu Chaoqun , Qin Weidu , He Congli , Shen Shipeng , Zhang Ying , Wang Shouguo
Published: April 2022

High performance of the generation, stabilization and manipulation of magnetic skyrmions prompts the application of topological multilayers in spintronic devices. Skyrmions in synthetic antiferromagnets (SAF) have been considered as a promising alternative to overcome the limitations of ferromagnetic skyrmions, such as the skyrmion Hall effect and stray magnetic field. Here, by using the Lorentz transmission electron microscopy, the interconversion between the single domain, labyrinth domain and skyrmion state can be observed by the combined manipulation of electric current and magnetic field in a Hall balance (a SAF with the core structure of [Co/Pt]4/NiO/[Co/Pt]4 showing perpendicular magnetic anisotropy). Furthermore, high-density room temperature skyrmions can be stabilized at zero field while the external stimulus is removed and the skyrmion density is tunable. The generation and manipulation method of skyrmions in Hall balance in this study opens up a promising way to engineer SAF-skyrmion-based memory devices.