bluuebunny/crossref_metadata_2025 huggingface dataset:
Feasibility of Opioid-Free Anesthesia for Cervical Rib Excision: A Case Series and Review of Literature
Authors: Dey Souvik , Kohli Jasvinder Kaur , Magoon Rohan , ItiShri ItiShri , Kashav Ramesh Chand
Published: February 2022

Background Perioperative pain management following cervical rib excision can be compounded in the background of chronic pain disorder caused by the neurovascular compression. The former mandates an enhanced analgesic requirement wherein the perioperative opioid use, in particular, can be associated with a peculiar adverse-effect profile and abuse potential. Appropriate to the context, an opioid-free anesthesia (OFA) protocol can be instrumental in minimizing the incidence of the aforementioned.

Case Series While two patients necessitated OFA owing to opioid contraindication, the formulated protocol was evaluated in another six consecutive patients posted for elective cervical rib excision. A combined paravertebral block and superficial cervical plexus block was employed alongside general anesthesia. Intravenous dexmedetomidine and lignocaine assisted the conduct of OFA, and paracetamol dosing was continued into the postoperative period. Intraoperative rescue analgesia was ensured by a ketofol bolus (1:1 mixture of ketamine and propofol) whereas intravenous diclofenac was used for postoperative rescue analgesia.

Results OFA could be successfully contemplated in all eight patients. A single bolus rescue dose of ketofol had to be administered in two patients intraoperatively and diclofenac had to be administered as postoperative rescue analgesic in two patients. There was no incidence of postoperative nausea/vomiting or any block-related complications. The postoperative stay was uneventful with an acceptable patient satisfaction.

Conclusion The index experience reiterates the fact that a prudent combination of nonopioid multimodal analgesics with case-based locoregional techniques can feature as a successful OFA protocol, albeit mandating future prospective studies in this novel area of clinical interest.
From Propped up to Prone: A Paradigm Shift in the Management of Severe COVID Pneumonia!
Authors: Choudhury Arindam , Senathipati Deva
Published: February 2022

Coronavirus disease (COVID) pneumonia in the recent times has shown us the importance of prone positioning during the management of moderate to severe hypoxia. In fact, we have rediscovered the benefits of this positional maneuver in coping with the “oxygen crisis” during the second wave of this dreaded pandemic. While we (the clinicians) derive benefits of this postural therapy for treating our patients, it is imperative for us to know the underlying mechanisms behind improvement in oxygenation in mild to moderate cases of COVID pneumonia. In this brief communication, we try to decipher the miracles of this great “life-saver.”
Comparative Study of Effect of Continuous versus Intermittent Subglottic Suctioning by the Suction Above the Cuff Endotracheal Tube (SACETT) on Tracheal Mucosa and Incidence of VAP in Intensive Care Unit
Authors: Anand Ravi , Singh Siddhart , Prasoon Anand , Kumar Sanjeev , Singh Ritu , Nayan Santosh Kumar
Published: February 2022

Context Ventilator-associated pneumonia (VAP) is one of the important causes of morbidity and mortality in patients admitted to the intensive care unit (ICU) with ventilatory support. Subglottic secretion and their aspirations are primarily responsible for the occurrence of VAP and the risk of tracheal mucosa injury induced by subglottic suctioning and the risk of VAP inpatient on a ventilator has been raised.

Aims Aim of this study is to compare the effect of continuous suctioning of subglottic secretions (CSSSs) versus intermittent suctioning of subglottic secretions (ISSS) on tracheal mucosa damage and incidence of VAP inpatient on a ventilator in both study groups.

Settings and Design A prospective randomized study.

Methods and Material A total of 140 patients requiring intubation or reintubation in the ICU with an expected ventilation duration > 24 hours were included in two groups: CSSS and ISSS. The effect on tracheal mucosa in front of the suction port was assessed after intubation (T0) and before extubation (T1) by bronchoscopy. VAP was compared in both groups on the basis of clinical suspicion and positive culture of bronchoalveolar lavage.

Statistical Analysis Used The SAS statistical software version 9.4 (SAS Institute, Cary, North Carolina, United States) has been used for analysis. Chi-square of the Fisher's exact test and Student's t-test or the Wilcoxon rank-sum test were used for analysis.

Results A total of 127 patients were included and 89 patients (CSSS, n = 44 and ISSS, n = 45) were evaluable on the primary endpoint. The occurrence or worsening of tracheal mucosal damages did not differ between the two groups (CSSS, n = 12 [27.3%] vs. ISSS, n = 8 [17.7%], p = 0.365). Daily average volume of suctioned secretion was higher with ISSS (72 ± 100 vs. 18 ± 25 mL, p < 0.001). Negligible chance to aspirate was higher with CSSS (0.13 ± 0.15 vs. 0.03 ± 0.06 per day, p < 0.001).

Conclusion ISSS did not reduce mucosal damage as compared with CSSS. The aspirated volume was higher and the negligible chance to aspirate was lower with ISSS. The incidence of VAP was lower with CSSS.
Corona: PSVN: Hilfe und Unterstützung für die Mitarbeiter
Authors: Heeser Alexandra
Published: February 2022

Die Belastungssituation – gerade auf den Intensivstationen – war auch vor Corona schon enorm. Dennoch hat die Corona-Pandemie den Wertekonflikt der Beschäftigten dort noch verschärft und die emotionalen Herausforderungen weiter zugespitzt. Die Charité bietet mit ihrem Psychosozialen Versorgungsnetz (PSVN) insbesondere ihren Beschäftigten Unterstützung.
Rechtskolumne: Neues Jahr, alte Herausforderungen
Authors: Rybak Christian
Published: February 2022

Auf den neuen Bundesgesundheitsminister kommen viele Aufgaben zu. Wichtig wäre, die Frage der Erstattung neuer Untersuchungs- und Behandlungsmethoden weiter zu präzisieren.
The CoRisk-Index: a data-mining approach to identify industry-specific risk perceptions related to Covid-19
Authors: Stephany Fabian , Neuhäuser Leonie , Stoehr Niklas , Darius Philipp , Teutloff Ole , Braesemann Fabian
Published: February 2022

The global spread of Covid-19 has caused major economic disruptions. Governments around the world provide considerable financial support to mitigate the economic downturn. However, effective policy responses require reliable data on the economic consequences of the corona pandemic. We propose theCoRisk-Index: a real-time economic indicator of corporate risk perceptions related to Covid-19. Using data mining, we analyse all reports from US companies filed since January 2020, representing more than a third of the US workforce. We construct two measures—the number of ‘corona’ words in each report and the averagetext negativityof the sentences mentioning corona in each industry—that are aggregated in the CoRisk-Index. The index correlates with U.S. unemployment rates across industries and with an established market volatility measure, and it preempts stock market losses of February 2020. Moreover, thanks to topic modelling and natural language processing techniques, the CoRisk data provides highly granular data on different dimensions of the crisis and the concerns of individual industries. The index presented here helps researchers and decision makers to measure risk perceptions of industries with regard to Covid-19, bridging the quantification gap between highly volatile stock market dynamics and long-term macroeconomic figures. For immediate access to the data, we provide all findings and raw data on an interactive online dashboard.
Polarization, abstention, and the median voter theorem
Authors: Jones Matthew I. , Sirianni Antonio D. , Fu Feng
Published: February 2022

The median voter theorem has long been the default model of voter behavior and candidate choice. While contemporary work on the distribution of political opinion has emphasized polarization and an increasing gap between the “left” and the “right” in democracies, the median voter theorem presents a model of anti-polarization: competing candidates move to the center of the ideological distribution to maximize vote share, regardless of the underlying ideological distribution of voters. These anti-polar results, however, largely depend on the “singled-peakedness” of voter preferences, an assumption that is rapidly losing relevance in the age of polarization. This article presents a model of voter choice that examines three potential mechanisms that can undermine this finding: a relative cost of voting that deters voters who are sufficiently indifferent to both candidates, ideologically motivated third-party alternatives that attract extreme voters, and a bimodal distribution of voter ideology. Under reasonable sets of conditions and empirically observed voter opinion distributions, these mechanisms can be sufficient to cause strategically minded candidates to fail to converge to the center, or to even become more polarized than their electorate.
Legacy media as inhibitors and drivers of public reservations against science: global survey evidence on the link between media use and anti-science attitudes
Authors: Mede Niels G.
Published: February 2022

Public resentment toward scientific institutions, scholars, and their expertise challenges the status of science in society in many countries worldwide. It is thus essential to examine the global prevalence of such resentment—and the potential of legacy media to temper it, thanks to their ability to cultivate positive views of science, educate citizens, and connect publics to scientific discourse. However, existing research has mostly surveyed Western populations, focused on pro-science rather than anti-science views, rarely studied the role of media use, and often ignored country characteristics that may interact with media use. This secondary analysis addresses these caveats, drawing on the 2017–2020 wave of the World Values Survey (N = 70,867 in 49 countries) and three relevant country-level indicators (freedom of the press, populism, uncertainty avoidance). Findings indicate that anti-science attitudes vary substantially across countries and are more prevalent in many Latin American nations. Results of Bayesian multilevel regressions show that frequent use of newspapers, TV, and radio indeed alleviates anti-science attitudes in some countries—but fosters them in others, particularly in those where populist rhetoric is more prevalent in public discourse, potentially because such rhetoric often challenges science and academic expertise. These findings call for further comparative research on global reservations against science and reflections about their repercussions on the science-society nexus.
Phase space Schrödinger equation and quadratic friction
Authors: Dessano H. , Petronilo G. X. A. , Amorim R. G. G. , Santana A. E.
Published: February 2022

A general Lagrangian for a point particle that moves across a viscous field quadratically dependent on the velocity is found. Afterward, the system is quantized via the Weyl quantization rule, and an explicit expression for the wave function in phase space is found.
Almost synchronous quantum correlations
Authors: Vidick Thomas
Published: February 2022

The study of quantum correlation sets initiated by Tsirelson in the 1980s and originally motivated by questions in the foundations of quantum mechanics has more recently been tied to questions in quantum cryptography, complexity theory, operator space theory, group theory, and more. Synchronous correlation sets introduced by Paulsen et al. [J. Funct. Anal. 270, 2188–2222 (2016)] are a subclass of correlations that has proven particularly useful to study and arises naturally in applications. We show that any correlation that is almost synchronous, in a natural ℓ1 sense, arises from a state and measurement operators that are well-approximated by a convex combination of projective measurements on a maximally entangled state. This extends a result of Paulsen et al. [J. Funct. Anal. 270, 2188–2222 (2016)] that applies to exactly synchronous correlations. Crucially, the quality of approximation is independent of the dimension of the Hilbert spaces or of the size of the correlation. Our result allows one to reduce the analysis of many classes of nonlocal games, including rigidity properties, to the case of strategies using maximally entangled states that are generally easier to manipulate.
Non-thermal electron velocity distribution functions due to 3D kinetic magnetic reconnection for solar coronal plasma conditions
Authors: Yao Xin , Muñoz Patricio A. , Büchner Jörg
Published: February 2022

Magnetic reconnection can convert magnetic energy into kinetic energy of non-thermal electron beams. Those accelerated electrons can, in turn, cause radio emission in astrophysical plasma environments, such as solar flares via micro-instabilities. The properties of the electron velocity distribution functions (EVDFs) of those non-thermal beams generated by reconnection are, however, still not well understood, in particular, properties that are necessary conditions for some relevant micro-instabilities. We aim at characterizing the EVDFs generated in 3D magnetic reconnection by means of fully kinetic particle-in-cell code simulations. In particular, our goal is to identify the possible sources of free energy offered by the generated EVDFs and their dependence on the strength of the guide field. By applying a machine learning algorithm on the EVDFs, we find that (1) electron beams with positive gradients in their 1D parallel (to the local magnetic field direction) velocity distribution functions are generated in both diffusion region and separatrices. (2) Electron beams with positive gradients in their perpendicular (to the local magnetic field direction) velocity distribution functions are observed in the diffusion region and outflow region near the reconnection midplane. In particular, perpendicular crescent-shaped EVDFs (in the perpendicular velocity space) are mainly observed in the diffusion region. (3) As the guide field strength increases, the number of locations with EVDFs featuring a perpendicular source of free energy significantly decreases. The formation of non-thermal electron beams in the field-aligned direction is mainly due to magnetized and adiabatic electrons, while in the direction perpendicular to the local magnetic field, it is attributed to unmagnetized electrons.
HfO2-based ferroelectrics: From enhancing performance, material design, to applications
Authors: Chen Haiyan , Zhou Xuefan , Tang Lin , Chen Yonghong , Luo Hang , Yuan Xi , Bowen Chris R. , Zhang Dou
Published: February 2022

Nonvolatile memories are in strong demand due to the desire for miniaturization, high-speed storage, and low energy consumption to fulfill the rapid developments of big data, the Internet of Things, and artificial intelligence. Hafnia (HfO2)-based materials have attracted significant interest due to the advantages of complementary-metal–oxide–semiconductor (CMOS) compatibility, large coercive voltage, and superior ferroelectricity at an ultra-thin thickness. The comparable ferroelectricity to that of traditional perovskite materials and size advantage of HfO2 result in fascinating storage performance, which can be readily applicable to the fields of integrated non-volatile memories. This Review provides a comprehensive overview of recent developments in HfO2-based ferroelectrics with attention to the origin of ferroelectricity, performance modulation, and recent achievements in the material. Moreover, potential solutions to existing challenges associated with the materials are discussed in detail, including the wake-up effect, long-term fatigue behavior, and imprint challenges, which pave the way for obtaining HfO2-based ferroelectric materials and devices with long service life and high stability. Finally, the range of potential applications for these fascinating new materials is presented and summarized, which include non-volatile memories and neuromorphic systems. This Review intends to present the state-of-the-art HfO2-based ferroelectrics and to highlight the current challenges, possible applications, and future opportunities and can act as an update for recent developments in these intriguing materials and provide guidance for future researchers in the design and optimization of HfO2-based ferroelectric materials and devices.
Plasma structure and electron cross-field transport induced by azimuthal manipulation of the radial magnetic field in a Hall thruster E × B discharge
Authors: Bak J. , Kawashima R. , Romanelli G. , Komurasaki K.
Published: February 2022

Plasma structure and electron cross field in the z–θ plane of a Hall thruster E×B plasma under an azimuthally inhomogeneous magnetic field are studied by both experimental and numerical approaches. The work is intended to identify a primary role of electron dynamics on the structure formation by manipulating only the strongly magnetized electrons. The plasma potential distribution shows an axial–azimuthal variation; a low magnetic field region results in spatial potential saturation further downstream. The plasma density structure shows a 1D-like azimuthal variation with less axial deformation. A dense region is observed near the location of ∇B>0, where electrons are expected to undergo the ∇B and curvature drift toward the anode where neutrals are introduced. The potential structure is in close correlation to the Hall parameter distribution, indicating that electron dynamics plays a primary role in plasma structure formation, and via multiple consecutive stepwise physical steps, it eventually affects the density structure formation. In the z–θ space, the cross-field transport by E×B and diamagnetic drifts dominantly determines the electron flow and increases the overall axial electron mobility due to the azimuthal inhomogeneity. It is shown that most of the current is carried by the largest structure, but as the macroscopic structure fades out downstream, small structures grow and share the current. By considering the conservation laws, we show that a relation between azimuthal distributions of physical properties is formed to conserve the axial flux by a balance of specific forces, a balance between the resistive force and the magnetic force in the near-anode region and a balance between the electric/pressure force and the magnetic force in the acceleration and plume region, which differs from the Boltzmann relation satisfied in the radial dimension. Based on this principle, with a simplified test case having a uniform plasma density distribution, we show an analytic relation between azimuthal distributions of the magnetic field and the plasma potential and confirm the relation by a 2D hybrid simulation.
RF generation using a compact bench gyromagnetic line
Authors: Rossi J. O. , Yamasaki F. S. , Barroso J. J. , Greco A. F. , Rangel E. G. L. , Teixeira A. F. , Neto L. P. S. , Schamiloglu E.
Published: February 2022

The search for new technologies aiming to reach radiofrequency (RF) generation in different manners for diverse ends is a constant demand for several applications. The goal is to develop cost-effective and simpler systems compared to those that already exist. Our motivation is to reach an alternative way of generating RF in pulsed transmission systems employing a gyromagnetic nonlinear transmission line (GNLTL). The GNLTL consists of a ferrite-loaded-coaxial transmission line and can produce a large frequency spectrum with RF conversion efficiency above 10% from about 200 MHz up to the frequency of 2–4 GHz (S-band) for potential space-based applications. In a GNLTL, the signal amplitude is related to its propagation velocity since the peak voltage travels faster than its portion of lower amplitudes since the ferrite permeability decreases with the current amplitude. As the pulse crest travels faster than its valley, a time reduction happens in the output rise time, called pulse sharpening. Besides, the magnetic moments of ferrite dipoles initially aligned with the axial magnetic bias are displaced from their original position by the azimuthal field generated around the inner conductor by the current pulse, resulting in a damped precession movement. This movement happens along the line length as the current pulse propagates, inducing high-frequency oscillations. In short, the paper’s goal is to present the experimental results using a 60-cm gyromagnetic line to provide RF in the GHz range using a solenoid for magnetic bias on a testing bench. Finally, the paper discusses the influence of the azimuthal and the axial magnetic fields on the output signal with the ferrite rings operating in a saturation state during the current pulse propagation.
Red- and blue-detuned magneto-optical trapping with liquid crystal variable retarders
Authors: Piest B. , Vollenkemper V. , Böhm J. , Herbst A. , Rasel E. M.
Published: February 2022

We exploit red- and blue-detuned magneto-optical trapping (MOT) of 87Rb benefitting from a simplified setup and a novel approach based on liquid crystal variable retarders (LCVR). To maintain the trapping forces when switching from a red- to a blue-detuned MOT, the handedness of the circular polarization of the cooling beams needs to be reversed. LCVRs allow fast polarization control and represent compact, simple, and cost-efficient components, which can easily be implemented in existing laser systems. This way, we achieve a blue-detuned type-II MOT for 8.7 × 108 atoms of 87Rb with sub-Doppler temperatures of 44 μK well below the temperatures reached in a conventional 87Rb type-I MOT. The phase space density is increased by more than two orders of magnitude compared to the standard red-detuned type-I MOT. The setup can readily be transferred to any other systems working with 87Rb.
Optimization and experimental validation of a bi-focal lens in the microwave domain
Authors: Vial Benjamin , Whittaker Tom , Zhang Shiyu , Whittow William G. , Hao Yang
Published: February 2022

The design of photonic devices is usually done through analytical modeling or variation in geometry and material parameters to obtain the required functionalities. Here, we report the use of topology optimization to obtain a bi-focal lens that concentrates the electromagnetic field at different spatial positions depending on the wavelength. Numerical inverse design is carried out to obtain the permittivity layout, satisfying this objective. The resulting device is then 3D printed using two low-loss dielectrics, and experimental field mapping at microwaves demonstrates the ability to enhance the field locally at distinct locations for two separate frequencies.
High pressure-induced phase transition in nanocrystalline iron confined by single-walled carbon nanohorns
Authors: Nan Yanli , Lei Liuming , Zhang Zihan , Li Bo , Su Lei
Published: February 2022

This study examines the high-pressure structural properties of nanocrystalline Fe confined by single-walled carbon nanohorns (SWCNHs) and SWCNHs (filled with Fe nanoparticles) named Fe-filled SWCNHs up to a pressure of 21.8 GPa. In detail, the Fe-filled SWCNHs did not undergo a special structural transformation at up to 21.8 GPa, except the partial irreversible amorphization of graphene sheets forming the core part above ∼18 GPa. Cubic Fe (bcc Fe) and Fe3O4 coexisted simultaneously in the Fe-filled SWCNHs. The Fe encapsulated by the SWCNH underwent a reversible transformation from bcc Fe to a hexagonal Fe (hcp Fe) at 11.7 GPa and reversed to bcc Fe at 6.2 GPa with a width of the domain of coexistence of bcc hcp of the order of 5 GPa. Due to the effect of the special tubular confinement of the SWCNHs, the high-pressure behavior of Fe confined by them exhibited a sharp contrast to that of Fe confined by carbon nanotubes. In comparison to the bulk bcc Fe, hcp Fe, and Fe3O4, these nanocrystallines confined by SWCNHs had higher compressibility than their bulk phases. Fe3O4 did not exhibit any phase transformation until 21.8 GPa, where this was similar to the results of bulk Fe3O4.
Operating in a deep underground facility improves the locking of gradiometric fluxonium qubits at the sweet spots
Authors: Gusenkova Daria , Valenti Francesco , Spiecker Martin , Günzler Simon , Paluch Patrick , Rieger Dennis , Pioraş-Ţimbolmaş Larisa-Milena , Zârbo Liviu P. , Casali Nicola , Colantoni Ivan , Cruciani Angelo , Pirro Stefano , Cardani Laura , Petrescu Alexandru , Wernsdorfer Wolfgang , Winkel Patrick , Pop Ioan M.
Published: February 2022

We demonstrate flux-bias locking and operation of a gradiometric fluxonium artificial atom using two symmetric granular aluminum (grAl) loops to implement the superinductor. The gradiometric fluxonium shows two orders of magnitude suppression of sensitivity to homogeneous magnetic fields, which can be an asset for hybrid quantum systems requiring strong magnetic field biasing. By cooling down the device in an external magnetic field while crossing the metal-to-superconductor transition, the gradiometric fluxonium can be locked either at 0 or Φ0/2 effective flux bias, corresponding to an even or odd number of trapped fluxons, respectively. At mK temperatures, the fluxon parity prepared during initialization survives to magnetic field bias exceeding 100 Φ0. However, even for states biased in the vicinity of 1 Φ0, we observe unexpectedly short fluxon lifetimes of a few hours, which cannot be explained by thermal or quantum phase slips. When operating in a deep-underground cryostat of the Gran Sasso laboratory, the fluxon lifetimes increase to days, indicating that ionizing events activate phase slips in the grAl superinductor.
The rapid destruction of toroidal magnetic surfaces
Authors: Boozer Allen H.
Published: February 2022

The operation of ITER will require reliable simulations in order to avoid major damage to the device from disruptions. Disruptions are the sudden breakup of magnetic surfaces across the plasma volume—a fast magnetic reconnection. This reconnection can be caused by the growth of perturbations outside of the plasma core causing an ideal perturbation to the core. This causes an increasing ratio of the maximum to the minimum separation, Δmax/Δmin, between neighboring magnetic surfaces. Magnetic reconnection becomes a dominant process when magnetic field lines can quickly interchange connections over a spatial scale ar. This occurs when Δmax/Δmin≳ar/Δd, where Δd is the scale over which non-ideal effects make magnetic field lines indistinguishable. Traditional reconnection theory is fundamentally different. It is a study of the steady-state cancelation of oppositely directed magnetic field components across a thin layer. During more than sixty years, mathematical implications of Faraday's law have been derived that clarify and constrain the physics of fast magnetic reconnection. These are reviewed because they are not commonly known but are needed to understand and to place in context how an ideal magnetic evolution can cause reconnection to quickly become a dominant process no matter how small Δd/ar may be.
Dynamic routing through saturable absorption in graphene photonic resonators: Impact of carrier diffusion and finite relaxation time
Authors: Nousios Georgios , Christopoulos Thomas , Tsilipakos Odysseas , Kriezis Emmanouil E.
Published: February 2022

We assess the continuous wave and dynamic routing performance of a compact silicon-on-insulator disk resonator overlaid with a graphene monolayer at telecommunication wavelengths. Switching action is enabled by saturable absorption in graphene, controlled by a pump wave of only a few milliwatts. Graphene saturable absorption is modeled through a carrier rate equation that incorporates both the finite relaxation time and diffusion of photo-generated carriers, providing a realistic account of carrier dynamics. The overall nonlinear response of the resonator is evaluated with a rigorous mathematical framework based on perturbation theory and temporal coupled-mode theory. We thoroughly investigate the effects of carrier diffusion and finite relaxation time, both separately and together. We also take into account nonlinear refraction via a Kerr effect term and quantify its impact on the overall response. In order to suppress the Kerr effect, we replace silicon with silicon-rich nitride, allowing for the individual contributions of the resonator core and graphene (of opposite sign) to exactly compensate each other. Our results contribute to the understanding of carrier dynamics and their impact on the performance of practical graphene-based switching components.
Strong adhesion induced by liquid-like surface of metallic glasses
Authors: Liu Ming , Wan Zhihua , Wang Pengfei , Dong Wen , Zhang Qi , Sun Yonghao , Song Jian , Zhang Kaifeng , Zhou Hui , Zhao Shaofan , Chen Na , Bai Haiyang , Wang Weihua
Published: February 2022

Self-healing with the capability to be self-adhesive, which can recover from physical damage, is essential for space applications. However, regulatable adhesion under extreme space conditions has only been realized in low-dimensional materials and still poses a challenge on the discovery of suitable materials. Under an ultrahigh vacuum of 10−7 Pa, we found a strong adhesion between bulk Cu46Zr46Al8 metallic glasses with a maximum adhesion strength of 32.8 kPa, which is two orders of magnitude higher than that of the corresponding crystalline. This adhesion is suggested to be induced by a liquid-like layer on a bulk metallic glass surface, which has a high diffusion coefficient of 6.9 × 10−11 m2⋅s−1, even at a relatively low temperature of 263 K. By investigating the dynamics for this liquid-like layer, a special fractional Stokes–Einstein relationship was found. Inspired by this strong adhesion, metallic glasses can be proposed as one of the promising self-healing materials for future space applications.
Monitoring rock bolt safety based on FBG sensors
Authors: Dong Jianjun , Xie Zhengquan , Zheng Gaoyang , Gao Ke
Published: February 2022

A good bolt support structure effectively enhances the strength of the surrounding rock. Bolt support monitoring provides a basis for modifying and improving the design of this structure and enables safety hazards to be identified so that safe production can continue. A bolt fiber Bragg grating (FBG) stress sensor is developed based on FBG sensor technology, providing a data-driven analysis tool for monitoring the bolt stress in the working face. Continuous dynamic monitoring of the internal force distribution in a high-precision roadway bolt support structure is achieved through strict laboratory calibration, thus enabling comprehensive safety monitoring. Furthermore, the anchor FBG stress sensor is used to analyze the real-time stress variations in a bolt support structure during excavation. The results reveal the security evolution characteristics of bolts buried in shallow bedrocks and show that the security state varies with location (i.e., the roof, roadside, apex between roof and roadside, and apex between roadside and floor) and depth.
Flow and mass transfer characteristics for interacting side-by-side cylinders
Authors: Kingora Kamau , Burks Wes Lee , Sadat Hamid
Published: February 2022

This study investigates the local and global flow structures and mass transfer characteristics for a group of interacting side-by-side cylinders in unbounded flow. Configurations with 2, 3, 4, and 5 members are considered for a range of pitch-ratios (1.05≤S/D≤4) at the Reynolds number Re = 90. The focus is laid on the time-averaged and instantaneous local flow features including wake field, jet flow, vortical structures, λ2, pressure coefficient, and mass transfer coefficient as well as integral variables including hydrodynamic forces. Four flow regimes are identified based on the vortical structures and average stream-wise velocity field. At low pitch-ratio, the whole structure behaves like a single bluff body, while each member in the configuration behaves like an independent isolated bluff body when the pitch-ratio is large. Between these two regimes, asymmetrically and symmetrically deflected wake regimes are observed. Flow regimes dictate hydrodynamic and mass transfer characteristics such that a jump in the hydrodynamic forces and mass transfer coefficient is observed as the flow regime evolves from a single body to a deflected wake. The configuration's size and the position of member cylinders in the structure have more profound effects on hydrodynamic forces and mass transfer characteristics at small pitch-ratio. For all configurations, drag increases as one progresses deeper into the structure, while lift forces are always repulsive between any two neighboring cylinders. Member cylinders have comparable mass transfer coefficients at intermediate and high pitch-ratios, while exterior cylinders exhibit a higher mass transfer coefficient at low pitch-ratio. Overall, the structure's size has a more profound effect on the values of scalars at low pitch-ratios.
Mathematical tricks for pseudopotentials in the theories of nonlinear waves in plasmas
Authors: Dubinov Alexander E.
Published: February 2022

In the analysis of nonlinear waves in plasma, especially for the search for periodic waves, shock waves, and solitons, mechanical analogy methods are widely applicable. The most famous of them is the Sagdeev pseudopotential method. However, sometimes mathematical difficulties arise when deriving formulas for pseudopotentials. The author proposes three mathematical tricks to get around these difficulties and obtain exact formulas for pseudopotentials in cases where the direct, Sagdeev method is considered inapplicable: a trick based on the Lambert W-function, a trick based on the inverse function integration, and a trick based on reducing the theory equations to the Bernoulli differential equation (the Bernoulli pseudopotential method). This article, which is methodological by nature, provides detailed examples of the application of each of these tricks when deriving formulas for pseudopotentials.
Numerical investigation of droplet impact on heated surfaces with pillars
Authors: Xu Yunjie , Tian Linlin , Zhu Chunling , Zhao Ning
Published: February 2022

This work proposes an improved three-dimensional double multiple relaxation time lattice Boltzmann model that can correctly recover the macroscopic temperature equation. Using this model, the impact of a droplet on a heated surface with pillars is simulated, and the effects of pillar width (w) and distance between pillars (b) are analyzed in detail. Four boiling droplet types are numerically reproduced, namely, deposition boiling, contact boiling, transition boiling, and film boiling. In the deposition boiling regime, no vapor bubble generation is observed within the droplet, but secondary droplets are generated at the periphery of the droplet due to the sharp geometric profile of the pillars and the differences in the rate of evaporation. The difference between contact boiling and transition boiling lies in whether the droplet is always in contact with the surface. For conditions with large w values, contact boiling is not observed, due to the high-pressure peaks from below, while for smaller w, a transition from deposition boiling to transition boiling, then to contact boiling, and subsequently to transition boiling can be observed. Two obvious vortices are found in the center of the liquid film with decreased b, which results in bubble nucleation even at low Ja values. In addition, boiling may take place, in which a stable vapor layer is formed between the droplet and the surface by increasing Ja, which leads to a significant reduction in the heat transfer efficiency.
Effects of interstitial water on collapses of partially immersed granular columns
Authors: He Kang , Shi Huabin , Yu Xiping
Published: February 2022

The effects of interstitial water on the collapse of partially immersed granular columns are experimentally and numerically investigated. Experiments on the collapsing process of partially immersed granular columns over a horizontal bed are conducted in which the saturation level of the columns, H̃, is defined by the ratio of the initial interstitial water level height to the total height of the column. It is shown that the interstitial water generally speeds up the collapse if the column consists of coarse-grains but slows down the motion if the column consists of fine-particles. The final run-out of a coarse-grain column increases as the saturation level increases, while that of a fine-particle column first decreases as the saturation level increases until H̃=0.75 and then increases to a value still smaller than the final run-out in the relevant dry case. In the experiments, the drag force between the water and the particle phases seems to always accelerate the collapse of partially immersed columns. It is speculated that there is an additional inter-particle viscosity in the water-particle mixtures, which retards the collapsing processes and dominates over the drag force in fine-grain cases. In the present study, a particle-fluid two-phase model is then adopted to describe the collapsing dynamics of partially immersed granular columns in which the water–air interface in the granular mass is captured and the primary flow variables of both particle and water phases are resolved. The model is validated by the experimental results. The roles of the drag force and the pressure gradient force exerted on the particles by the interstitial water are then clarified. It is shown that the interphase drag and the pressure gradient force drive both coarse- and fine-grain columns to collapse, and their effects increase with an increase in the saturation level of the column. The significance of the additional inter-particle viscosity induced by the interstitial water is also discussed.
Transparent ultrathin Ag nanomesh electrode fabricated by nanosphere lithography for organic light-emitting devices
Authors: Zhang Tian-Run , Wang Ya-Nan , Liu Yue-Feng , Feng Jing
Published: February 2022

We report a transparent ultrathin Ag nanomesh electrode fabricated by nanosphere lithography combined with a dielectric wetting layer, which is simple and cost-effective. Compared with the continuous ultrathin film Ag electrode, the nanomesh electrode exhibits a higher figure of merit (FOM = T10/Rs, T is the transmittance and Rs is the sheet resistance) of 3.01 × 10−3 Ω−1, which is due to the retained high electrical conductivity and nanopores as optical windows. The maximum luminance and current efficiency enhancement of organic light emitting devices (OLEDs) with an ultrathin Ag nanomesh electrode are up to 56.2% and 41.4% compared to that of conventional devices with an ITO anode. It is worth noting that the ultrathin Ag nanomesh electrode has been proved able to resolve the emission intensity roll-off of OLEDs with dual metal electrodes as the enlargement of viewing angle due to the redistribution of the light emission direction derived from strong scattering. More light emission at larger angles is of great value for lighting panel applications.
Coherent and incoherent contributions to molecular electron transport
Authors: Mejía Leopoldo , Kleinekathöfer Ulrich , Franco Ignacio
Published: February 2022

We numerically isolate the limits of validity of the Landauer approximation to describe charge transport along molecular junctions in condensed phase environments. To do so, we contrast Landauer with exact time-dependent non-equilibrium Green’s function quantum transport computations in a two-site molecular junction subject to exponentially correlated noise. Under resonant transport conditions, we find Landauer accuracy to critically depend on intramolecular interactions. By contrast, under nonresonant conditions, the emergence of incoherent transport routes that go beyond Landauer depends on charging and discharging processes at the electrode–molecule interface. In both cases, decreasing the rate of charge exchange between the electrodes and molecule and increasing the interaction strength with the thermal environment cause Landauer to become less accurate. The results are interpreted from a time-dependent perspective where the noise prevents the junction from achieving steady-state and from a fully quantum perspective where the environment introduces dephasing in the dynamics. Using these results, we analyze why the Landauer approach is so useful to understand experiments, isolate regimes where it fails, and propose schemes to chemically manipulate the degree of transport coherence.
Extrinsic magnetoelectric effect at the BaTiO3/Ni interface
Authors: Li Wente , Lee Jaekwang , Demkov Alexander A.
Published: February 2022

We theoretically investigate the interfacial magnetoelectric effect in the BaTiO3/Ni heterostructure. We find that magnetoelectric coupling, specifically, the dependence of the magnetic moment of Ni on the polarization direction, primarily stems from the flow of the screening charge from Ni into BaTiO3 with a minor contribution coming from interfacial chemical bonding. The estimated change in the magnetic moment from screening with respect to bulk Ni is as high as ∼7%, which is a significant modulation. We also examine the effects of interfacial oxidation on the electronic structures and the strength of magnetoelectric coupling in the BaTiO3/NiO/Ni structure. We find an enhancement of the interfacial bonding contribution, making it unfavorable for interfacial magnetoelectric modulation. In addition, we consider the effect of the Ni magnetic domain wall on interfacial coupling and find it to be negligible to the interfacial magnetoelectric effect.
Dynamic measurement of impurity ion transport in runaway electron plateaus in DIII-D
Authors: Hollmann E. M. , Bortolon A. , Effenberg F. , Eidietis N. , Shiraki D. , Bykov I. , Chapman B. E. , Chen J. , Haskey S. , Herfindal J. , Lvovskiy A. , Marini C. , McLean A. , O'Gorman T. , Pandya M. D. , Paz-Soldan C. , Popović Ž.
Published: February 2022

The first dynamic (time-dependent) measurements of impurity ion radial (cross field) and parallel (along-field) diffusion coefficients for post-disruption runaway electron plateaus are presented. Small (∼1 mm diameter) carbon or silicon pellets are fired into the edge of steady-state runaway electron (RE) plateaus, and the resulting radial and toroidal transport of singly charged impurity ions (C+ or Si+) is monitored with spatially distributed visible spectrometers. Consistent with previous steady-state particle balance estimates of Ar+ radial transport, radial (cross field) diffusion coefficients D⊥≈2–5 m2/s are obtained, about 10× larger than expected from neo-classical theory. Parallel diffusion coefficients D∥≈30–80 m2/s are estimated, also much (≈50×) larger than classical. It is speculated at present that these large diffusion coefficients may be due to turbulent transport. Indications of fairly significant (almost 2×) toroidal variation in electron density are seen in the RE plateaus, and this appears to cause some toroidal variation in impurity radial diffusion rates. Indications of slow (≈1 Hz) toroidal rotation in the impurity ions are observed, although the uncertainty in this measurement is large.
Low-strain effective Young’s modulus model and validation for multi-layer vocal fold-based silicone specimens with inclusions
Authors: Ahmad M. , Pelorson X. , Fernández I. A. , Guasch O. , Van Hirtum A.
Published: February 2022

A model of the effective low-strain elastic Young’s modulus of multi-layer stacked composites is proposed, which is capable to account for an arbitrary stacked inclusion. Geometrical and discretization-based model results are validated against measured effective Young’s moduli (from 10 up to 40 kPa) on 14 molded silicone specimens embedding a stiff (298 kPa) inclusion with variable size, position, and stacking. Specimens without inclusion represent the muscle, superficial, and epithelium layers in a human vocal fold with Young’s moduli between 4 and 65 kPa. The proposed model allows to predict the influence of a stiff inclusion, mimicking a structural abnormality or pathology somewhere within the vocal fold, on the low-strain effective Young’s modulus. Quantifying the influence of an inclusion or local stiffening on the vocal fold bio-mechanics is a necessary step toward the understanding and mitigation of structural vocal fold pathologies and associated voice disorders.
An improved multicomponent pseudopotential lattice Boltzmann method for immiscible fluid displacement in porous media
Authors: Sedahmed M. , Coelho R. C. V. , Warda H. A.
Published: February 2022

Immiscible fluid displacement in porous media occurs in several natural and industrial processes. For example, during petroleum extraction from porous rock reservoirs, water is used to displace oil. In this paper, we investigate the primary drainage and imbibition in a heterogeneous porous medium using an improved numerical model based on the multicomponent pseudopotential lattice Boltzmann method. We apply recent developments from the literature and develop new pressure boundary conditions. We show that the proposed model is able to simulate realistic viscosity ratios, and it allows independent tuning of surface tension from viscosity. Moreover, the model suppresses a nonphysical behavior of previous schemes, in which trapped fluid volumes significantly change with time. Furthermore, we show that the developed model correctly captures the underlying physical phenomena of fluid displacements. We simulate oil–water flows and verify that the measured values of irreducible water and residual oil saturations are realistic. Finally, we vary the wetting conditions of the porous medium to represent different wettability states. For the different scenarios, we show that the simulations are in good agreement with the experimental results.
Large eddy simulation of cavitating flow around a twist hydrofoil and investigation on force element evolution using a multiscale cavitation model
Authors: Wang Zhengdong , Li Linmin , Li Xiaojun , Zhu Zuchao
Published: February 2022

Cavitating flows always include micro-bubbles and macro-cavities over a wide range of length scale, and understanding the vorticity force evolution induced by cavitation is also a challenging issue. In the present work, a hybrid multiscale cavitation model incorporated with the large eddy simulation approach is applied for comprehensively revealing the unsteady cavitating flow features. The macroscale cavities are captured by the volume of fluid (VOF) method while the microscale bubbles are modeled using a discrete bubble model (DBM) in the Lagrangian way. Simulations of the cavitating flow on a twist hydrofoil are performed and validated against the experimental result. Good agreement in terms of cavity morphology and shedding frequency is obtained. Applying the multiscale cavitation model, the microscale cavitation bubbles that are unable to be predicted by the VOF method are well represented especially in the region near the trailing edge. To investigate the vorticity force evolution, the force element method is adopted to quantitatively analyze the change of force elements along with the evolution of the cavity. The overall effect of cavitation on the lift and drag forces is also investigated. Finally, the superiority of the multiscale VOF-DBM model is attested compared with the original VOF method.