bluuebunny/crossref_metadata_2025 huggingface dataset:
Music Listening Habits and Music Perception Abilities of Prelingually Deafened Adolescent Cochlear Implant Recipients
Authors: Yüksel Mustafa , Atılgan Atılım , Çiprut Ayça
Published: December 2020

Abstract Background Music is a very important art form that can evoke strong emotions and involvement with it can have a considerable impact on cochlear implant (CI) recipients' quality of life. It is well known that music perception is limited in CI with fully
electric hearing and CI recipients have significantly poorer music-appraisal ability when compared with normal hearing subjects. Considering the importance of music on the life of an adolescent and negative impact of hearing loss on mental health, understanding and improving music listening
habits and perception abilities can have a positive impact on the mental health of CI user adolescents. Purpose This study aims to evaluate music listening habits and music perception abilities of prelingually deafened adolescent CI users to reveal the relationship between
self-reported assessment and psychophysical measurement. Research Design The psychophysical measures of music perception and self-reported music listening habits of adolescent CI users were obtained. Study Sample Twenty-nine prelingually deafened adolescent
CI users were evaluated in this study. Data Collection and Analysis The Turkish Clinical Assessment of Music Perception (T-CAMP) test was used to evaluate music perception abilities. These abilities were evaluated with a three-item questionnaire assessing enjoyment of music,
listening habits, and comprehension of lyrics. Pearson's correlation coefficients were calculated to assess the relationship between the T-CAMP subtests and questionnaire items. Results Statistically significant correlations were observed between the melody-recognition subtest
of T-CAMP and all three questionnaire items. The correlation between the enjoyment and rate items on the questionnaire was also statistically significant. Conclusion The present study shows that adolescent CI users also enjoy and listen to music in ways similar to postlingually
deafened adult CI users. It also demonstrates that melody-recognition abilities have a significant relationship with music enjoyment and listening habits in prelingually deafened adolescent CI users.
Awareness on Preventive Measures taken by Health Care Professionals Attending COVID-19 Patients among Dental Students
Authors: Princeton Bianca , Santhakumar Preetha , Prathap Lavanya
Published: December 2020

Objectives Coronavirus disease is an infectious disease caused by a newly discovered coronavirus. This virus primarily spreads through droplets of saliva or discharge from the nose when an infected person coughs or sneezes. This virus was named after its shape, which takes the form of a crown with protrusions around it. The World Health Organization has recommended personal protective equipments (PPE) to doctors and health care workers attending COVID-19 patients. PPE generally includes masks, goggles, respirators, gloves, face shields, and isolation gowns. The principle aim of this study is to create awareness among dental students about the preventive measures taken by health care professionals while attending patients affected with COVID-19.

Materials & Methods A questionnaire comprising 15 questions was created using an online Google forms website and was circulated among 100 dental students. The survey was conducted within a week in the months of April to May 2020. The results and observations were recorded in the form of pie charts.

Results Ninety-three percent of the participants have stated that health care professionals must clean their hands often, cover their nose and mouth, and maintain safe distance from everyone in order to prevent the virus from affecting them. Sixty-three percent of the participants are familiar with the term PPE. Majority assume that health care professionals are given enough safety precautions while treating a patient with coronavirus.

Conclusion Hence, to conclude, health care professionals play a vital role in improving access and quality health care for the population, and hence, they must be protected as well. Since dental students treat patients, they are vulnerable to infection as well, and must take proper safety measures.
Evaluation of Pediatric Delirium Awareness and Management in Pediatric Intensive Care Units in Turkey
Authors: Konca Capan , Anil Ayse Berna , Küllüoglu Emine Pinar , Luleyap Doga , Anil Murat , Tekin Mehmet
Published: December 2020

Delirium has been associated with prolonged pediatric intensive care unit (PICU) stay and mechanical ventilation times as well as high hospital costs and mortality rates. This work aimed to examine pediatric delirium awareness and delirium management in Turkey. A total of 19 physicians responsible for their respective PICUs completed the survey. Most of the units (57.9%) did not use any assessment tool. Varying measures were applied in different units to reduce the prevalence of delirium. The number of units that continuously measured noise was very low (15.8%). Eye mask and earpiece usage rates were also very low. In pharmacological treatment, haloperidol, dexmedetomidine, benzodiazepines, and atypical antipsychotics were the most preferred options. Some units have reached a sufficient level of pediatric delirium awareness and management. However, insufficiencies in delirium awareness and management remain in general.
Intrapartum Basal Ganglia–Thalamic Pattern Injury and Radiologically Termed “Acute Profound Hypoxic–Ischemic Brain Injury” Are Not Synonymous
Authors: Smith Johan , Solomons Regan , Vollmer Lindi , Langenegger Eduard J. , Lotz Jan W. , Andronikou Savvas , Anthony John , van Toorn Ronald
Published: December 2020

Objective Human cases of acute profound hypoxic-ischemic (HI) injury (HII), in which the insult duration timed with precision had been identified, remains rare, and there is often uncertainty of the prior state of fetal health.

Study Design A retrospective analysis of 10 medicolegal cases of neonatal encephalopathy-cerebral palsy survivors who sustained intrapartum HI basal ganglia-thalamic (BGT) pattern injury in the absence of an obstetric sentinel event.

Results Cardiotocography (CTG) admission status was reassuring in six and suspicious in four of the cases. The median time from assessment by admission CTG or auscultation to birth was 687.5 minutes (interquartile range [IQR]: 373.5–817.5 minutes), while the median time interval between first pathological CTG and delivery of the infant was 179 minutes (IQR: 137–199.25 minutes). The mode of delivery in the majority of infants (60%) was by unassisted vaginal birth; four were delivered by delayed caesarean section. The median (IQR) interval between the decision to perform a caesarean section and delivery was 169 minutes (range: 124–192.5 minutes).

Conclusion The study shows that if a nonreassuring fetal status develops during labor and is prolonged, a BGT pattern HI injury may result, in the absence of a perinatal sentinel event. Intrapartum BGT pattern injury and radiologically termed “acute profound HI brain injury” are not necessarily synonymous. A visualized magnetic resonance imaging (MRI) pattern should preferably solely reflect the patterns description and severity, rather than a causative mechanism of injury.

Key Points
A Novel Simulation Model for Resident Education in Mechanical Cervical Ripening
Authors: Gimovsky Alexis C. , Pham Amelie , Gimovsky Martin , Wolf Abigail
Published: December 2020

Introduction This study aims to evaluate resident satisfaction with a novel simulation model for learning transcervical balloon catheter placement for mechanical cervical ripening.

Study Design A descriptive pretest and post-test survey study of Obstetrics and Gynecology (OBGYN) residents was conducted at a single academic medical center using a low-cost model.

Results Of 28 residents, 14 (50%) were recruited. 100% of participants completed the pretest and post-test survey. Residents agreed that both learning and achieving correct placement of a transcervical balloon catheter are difficult. Pretest and post-test comparisons were statistically different with respect to comfort (2.8 ± 1.5 vs. 4.0 ± 1.0, p = 0.03) and ease of learning (3.1 ± 0.8 vs. 4.1 ± 0.6, p ≤ 0.001).

Discussion We present a novel simulation model that can be used by OBGYN residents in training for learning transcervical balloon catheter placement for mechanical cervical ripening.

Key Points
Discharge properties of a coaxial plasma jet at different microwave frequencies
Authors: Wu Li , Zhang Wencong , Liu Zhuang , Yu Jie , Tao Junwu , Yang Yang , Huang Kama
Published: December 2020

This article investigated the discharge characteristics of Ar plasma sustained by a coaxial plasma jet under different microwave frequencies (433 MHz, 915 MHz, 2450 MHz, and 5800 MHz). Clear distinctions of the discharge characteristics such as excitation and plasma-sustaining power, shape, electron number density, electron temperature, and so on were experimentally obtained under these operating frequencies. The results demonstrated that microwave powers at different frequencies could excite distinct particles. The higher the microwave frequency, the lower the excitation and the plasma-sustaining power. However, these powers did not decline linearly to the increase in microwave frequency. The Ar plasma at a frequency of 5800 MHz exhibited an upside-down “bell” shape and a larger cross section, while those at other three frequencies seemed to have thin and long plumes. The investigation also revealed that the electron temperature increased and then decreased, while the electron number density and gas temperature elevated monotonously with increasing frequency. This study is intended to be helpful in determining the optimal frequency and design microwave plasma sources for certain applications.
Electrode-induced polarity conversion in Nb2O5/NbOx resistive switching devices
Authors: Zhou Ziliang , Yang Mei , Fu Zhen , Wang Hong , Ma Xiaohua , Gao Haixia
Published: December 2020

Applications in neuromorphic computing and next-generation memories require a deep understanding of the physical mechanisms in resistive switching (RS) devices. Here, we report electrode-induced polarity conversion in Nb2O5/NbOx RS devices, where Nb2O5 and NbOx are a switching layer and an oxygen vacancy (Vo··) reservoir, respectively. The reservoir provides the Vo·· s, comprising a conductive filament formed during an electroforming process. After the process, the devices with an inert Pt top electrode show a clockwise RS behavior. However, the ones with a reactive W top electrode exhibit a counterclockwise RS behavior. Detailed explorations suggest that reactive electrodes provide an oxygen ion reservoir near the active region of the conductive filaments. The reservoir dominates the rupture and recovery of the conductive filaments through interfacial redox reaction, which induces the switching polarity conversion. This study indicates that oxygen ion distribution and migration near a conductive filament tip have the dominant effect on switching processes of oxide RS devices.
Analytical methods for fast converging lattice sums for cubic and hexagonal close-packed structures
Authors: Burrows Antony , Cooper Shaun , Pahl Elke , Schwerdtfeger Peter
Published: December 2020

Fast convergent series are presented for lattice sums associated with the simple cubic, face-centered cubic, body-centered cubic, and hexagonal close-packed structures for interactions described by an inverse power expansion in terms of the distances between the lattice points, such as the extended Lennard-Jones potential. These lattice sums belong to a class of slowly convergent series, and their exact evaluation is related to the well-known number-theoretical problem of finding the number of representations of an integer as a sum of three squares. We review and analyze this field in some detail and use various techniques such as the decomposition of the Epstein zeta function introduced by Terras or the van der Hoff–Benson expansion to evaluate lattice sums in three dimensions to computer precision.
Increased hot electron production from the addition of a gas cell in sub-picosecond laser–foil interactions
Authors: Peterken T. , Robinson A. P. L. , Trines R. M. G. M. , Clarke R. J.
Published: December 2020

A number of recent experiments at the VULCAN laser at the Rutherford Appleton Laboratory involving high intensity (1019 W/cm2) sub-picosecond laser pulses incident on thin (∼10 μm) metal foils for use as a proton probe have suggested that the addition of a gas cell behind the foil results in a significant increase in the production of hard x rays, particularly in the direction counter to the incident laser direction. In this paper, we consider two mechanisms that might contribute to this effect. Analysis of these two mechanisms indicates that there are plausible physical mechanisms that could give rise to the observations, and thus the physics of these gas-cell targets merits further study.
Generation of diverse insect-like gait patterns using networks of coupled Rössler systems
Authors: Kitsunai Shunki , Cho Woorim , Sano Chihiro , Saetia Supat , Qin Zixuan , Koike Yasuharu , Frasca Mattia , Yoshimura Natsue , Minati Ludovico
Published: December 2020

The generation of walking patterns is central to bio-inspired robotics and has been attained using methods encompassing diverse numerical as well as analog implementations. Here, we demonstrate the possibility of synthesizing viable gaits using a paradigmatic low-dimensional non-linear entity, namely, the Rössler system, as a dynamical unit. Through a minimalistic network wherein each instance is univocally associated with one leg, it is possible to readily reproduce the canonical gaits as well as generate new ones via changing the coupling scheme and the associated delays. Varying levels of irregularity can be introduced by rendering individual systems or the entire network chaotic. Moreover, through tailored mapping of the state variables to physical angles, adequate leg trajectories can be accessed directly from the coupled systems. The functionality of the resulting generator was confirmed in laboratory experiments by means of an instrumented six-legged ant-like robot. Owing to their simple form, the 18 coupled equations could be rapidly integrated on a bare-metal microcontroller, leading to the demonstration of real-time robot control navigating an arena using a brain–machine interface.
Thermal stability for domain wall mediated magnetization reversal in perpendicular STT MRAM cells with W insertion layers
Authors: Mihajlović G. , Smith N. , Santos T. , Li J. , Terris B. D. , Katine J. A.
Published: December 2020

We present an analytical model for calculating the energy barrier for the magnetic field-driven domain wall-mediated magnetization reversal of a magneto-resistive random access memory cell and apply it to study thermal stability factor Δ for various thicknesses of W layers inserted into the free layer (FL) as a function of the cell size and temperature. We find that, by increasing the W thickness, the effective perpendicular magnetic anisotropy (PMA) energy density of the FL film monotonically increases, but at the same time, Δ of the cell mainly decreases. Our analysis shows that, in addition to saturation magnetization Ms and exchange stiffness constant Aex of the FL film, the parameter that quantifies the Δ value of the cell is its coercive field Hc, rather than the net PMA field Hk of the FL film comprising the cell.
Stationary states of polytropic plasmas
Authors: Guo Ran
Published: December 2020

In this paper, we prove that the kappa distribution is the stationary solution of the Vlasov–Poisson system in an inhomogeneous plasma under the polytropic equation of state and an assumption restricting the local velocity distribution to a specific mathematical form. The profiles of density, temperature, and electric potential are obtained theoretically. The kappa index can be determined if the initial state is known. In order to verify the theory, particle-in-cell simulations are made and the results show excellent agreement with the theoretical predictions for density, temperature, and velocity distributions of electrons. It is shown that the electron velocity distribution of spatially inhomogeneous plasma evolves from an initial Maxwellian to the final kappa distribution. It is also found that the value of kappa index in the final stationary state depends on the initial state of plasma.
Investigation of the microchannel structure in the initial phase of the discharge in air at atmospheric pressure in the “pin (anode)-plane” gap
Authors: Almazova K. I. , Belonogov A. N. , Borovkov V. V. , Kurbanismailov V. S. , Khalikova Z. R. , Omarova P. Kh. , Ragimkhanov G. B. , Tereshonok D. V. , Trenkin A. A.
Published: December 2020

The results of studies of the microstructure in the initial phase of the discharge in air in the gap between the pin and a plane 1.5 mm long are presented. Measurements show that within 15 ns after breakdown, the channel is a bundle of a large number of microchannels, the current in the channel grows almost linearly up to 1 kA, and the electron concentration reaches 2 × 1019 cm−3. Taking into account the experimental data, the electron temperature dynamics in a separate microchannel was calculated. It was found that the average electron temperature is from 4 to 8 eV, the electric field strength is ∼300 kV/cm, and the electrical conductivity is ∼10 Ω−1 cm−1. The obtained results indicate that it is the microstructure of the discharge that determines the relatively high values of the average temperature of electrons in combination with a sufficiently high degree of ionization.
Numerical study of a sonic jet in a supersonic crossflow over a flat plate
Authors: Rasheed Imran , Mishra Debi Prasad
Published: December 2020

A sonic circular injector discharging into a Mach 1.6 freestream over a flat plate with a jet to crossflow momentum flux ratio of 1.73 is investigated numerically using a three-dimensional Reynolds-averaged Navier–Stokes equation. Menter’s shear stress transport k–ω turbulence model is employed to understand the complex flow features associated with jet–freestream interaction. The validation of the numerical solution is achieved by comparing the velocity and flat plate surface pressure measurements from the experiments, and the numerical solution shows good agreement with the experimental data. The present work emphasizes the flow field studies that include the identification of shocks, recirculation zones, and vortex structures. The Omega (Ω) vortex visualization method is employed for identifying the vortex structures. Comparison with high Mach number freestream conditions (M∞ = 2 and 4) shows that the vortex structures remain the same, irrespective of the freestream Mach number. A close analysis of the jet near-field shows several new vortex structures, including a secondary surface trailing vortex. The formation of each of these vortices lacks clarity to date. Considering the complex three-dimensional nature of the flow field, an attempt has been made to trace the formation of the vortex structures associated with a jet in supersonic crossflow.
Sign reversal in magnetic field amplification by relativistic laser-driven microtube implosions
Authors: Weichman K. , Murakami M. , Robinson A. P. L. , Arefiev A. V.
Published: December 2020

We demonstrate and explain the surprising phenomenon of sign reversal in magnetic field amplification by the laser-driven implosion of a structured target. Relativistically intense laser pulses incident on the outer surface of a microtube target consisting of a thin opaque shell surrounding a μm-scale cylindrical void drive an initial ion implosion and later explosion capable of generating and subsequently amplifying strong magnetic fields. While the magnetic field generation is enhanced and spatially smoothed by the application of a kilotesla-level seed field, the sign of the generated field does not always follow the sign of the seed field. One unexpected consequence of the amplification process is a reversal in the sign of the amplified magnetic field when, for example, the target outer cross section is changed from square to circular. Using 2D particle-in-cell simulations, we demonstrate that sign reversal is linked to the stability of the surface magnetic field of opposite sign from the seed, which arises at the target inner surface during laser irradiation. The stability of the surface magnetic field and, consequently, the sign of the final amplified field depend sensitively on the target, laser, and seed magnetic field conditions, which could be leveraged to make laser-driven microtube implosions an attractive platform for the study of magnetic fields in high energy density plasma in regimes where sign reversal either is or is not desired.
Simulated expansion and ion front formation of ultracold plasma
Authors: Vikhrov E. V. , Bronin S. Ya. , Klayrfeld A. B. , Zelener B. B. , Zelener B. V.
Published: December 2020

We report the direct molecular dynamics simulation results of the ultracold two-component plasma expansion. Interaction between charges is described by Coulomb's law. The number of particles varies from 103 to 105. It is shown in this article that the expansion of the plasma begins with the evaporation of some of the electrons and with the transfer of their kinetic energy to the energy of the electric field. After that, the field increases the kinetic energy of the ions. An important result is the detection of the supersonic ion wave formation. On the basis of the calculation results, equations and self-similar solutions are obtained. General dependences on plasma parameters are determined, which are compared with experimental data.
Bubble entrapment during head-on binary collision with large deformation of unequal-sized tetradecane droplets
Authors: Goyal Nitin , Shaikh Javed , Sharma Atul
Published: December 2020

Head-on collision dynamics of unequal-sized binary tetradecane droplets in air is numerically studied for numerous diameter ratios Dr = 1.5–2.5 and larger values of Weber number We = 50–220. Our study is within two collision regimes, permanent coalescence and separation after temporary coalescence, where entrapment of an air bubble is revealed at larger We and intermediate values of Dr. We found two types of bubble entrapment, permanent and temporary, which are demarcated—within the two collision regimes—in a regime map, with the transition from the permanent to temporary entrapment at a larger We and larger Dr. A bubble-entrapment mechanism is proposed in three stages: stage-1 is radial expansion and a thin lamella-layer formation at the center of the coalesced droplets, stage-2 is radial contraction and an advancing lamella layer that results in a horseshoe-like droplet, and stage-3 is radial contraction and a receding lamella layer. Inertia force dominates stage-1, while both inertia and surface tension forces dominate stage-2 and stage-3. Finally, a quantitative analysis is presented for the effect of We and Dr on the unsteady interface dynamics of the initially disk-like and later horseshoe-like coalesced droplets, which leads to the bubble entrapments. The present findings are significant as bubble entrapments inside a fuel droplet facilitate a micro-explosion during combustion. It can also lead to a novel technique for the production of a compound droplet, which is used to achieve a precise control over processes in many applications, such as bio-analysis, pharmaceutical manufacturing, and material synthesis.
A method for estimating defects in ferroelectric thin film MOSCAPs
Authors: Persson Anton E. O. , Athle Robin , Svensson Johannes , Borg Mattias , Wernersson Lars-Erik
Published: December 2020

We propose a capacitance measurement scheme that enables quantitative characterization of ferroelectric thin films integrated on semiconductors. The film defect density is estimated by measurements of the CV hysteresis and frequency dispersion, whereas important device parameters such as memory window and endurance can be extracted by a unidirectional CV method. The simple measurement scheme and the usage of metal-oxide-semiconductor capacitors rather than MOSFETs make the proposed methods suitable for the future optimization of ferroelectric field effect transistor and negative capacitance field effect transistor gate stacks. Specifically, we present data for the narrow bandgap semiconductor InAs and show that low temperature characterization is critical to reduce the influence of the minority carrier response; however, the methods should be transferrable to room temperature for semiconductors with a wider bandgap. Our results clearly indicate that the defect density of the HfxZr1−xO2 (HZO) films increases at the crystallization temperature, but the increase is modest and remains independent of the annealing temperature at even more elevated temperatures. It is also shown that the shrinkage of the memory window caused by field cycling is not accompanied by an increase in defect density.
Index of multi-determinantal and multi-reference character in coupled-cluster theory
Authors: Bartlett Rodney J. , Park Young Choon , Bauman Nicholas P. , Melnichuk Ann , Ranasinghe Duminda , Ravi Moneesha , Perera Ajith
Published: December 2020

A full configuration interaction calculation (FCI) ultimately defines the innate molecular orbital description of a molecule. Its density matrix and the natural orbitals obtained from it quantify the difference between having N-dominantly occupied orbitals in a reference determinant for a wavefunction to describe N-correlated electrons and how many of those N-electrons are left to the remaining virtual orbitals. The latter provides a measure of the multi-determinantal character (MDC) required to be in a wavefunction. MDC is further split into a weak correlation part and a part that indicates stronger correlation often called multi-reference character (MRC). If several virtual orbitals have high occupation numbers, then one might argue that these additional orbitals should be allowed to have a larger role in the calculation, as in MR methods, such as MCSCF, MR-CI, or MR-coupled-cluster (MR-CC), to provide adequate approximations toward the FCI. However, there are problems with any of these MR methods that complicate the calculations compared to the uniformity and ease of application of single-reference CC calculations (SR-CC) and their operationally single-reference equation-of-motion (EOM-CC) extensions. As SR-CC theory is used in most of today’s “predictive” calculations, an assessment of the accuracy of SR-CC at some truncation of the cluster operator would help to quantify how large an issue MRC actually is in a calculation, and how it might be alleviated while retaining the convenient SR computational character of CC/EOM-CC. This paper defines indices that identify MRC situations and help assess how reliable a given calculation is.
Attenuating the fermion sign problem in path integral Monte Carlo simulations using the Bogoliubov inequality and thermodynamic integration
Authors: Dornheim Tobias , Invernizzi Michele , Vorberger Jan , Hirshberg Barak
Published: December 2020

Accurate thermodynamic simulations of correlated fermions using path integral Monte Carlo (PIMC) methods are of paramount importance for many applications such as the description of ultracold atoms, electrons in quantum dots, and warm-dense matter. The main obstacle is the fermion sign problem (FSP), which leads to an exponential increase in computation time both with an increase in the system size and with a decrease in the temperature. Very recently, Hirshberg et al. [J. Chem. Phys. 152, 171102 (2020)] have proposed to alleviate the FSP based on the Bogoliubov inequality. In the present work, we extend this approach by adding a parameter that controls the perturbation, allowing for an extrapolation to the exact result. In this way, we can also use thermodynamic integration to obtain an improved estimate of the fermionic energy. As a test system, we choose electrons in 2D and 3D quantum dots and find in some cases a speed-up exceeding 106, as compared to standard PIMC, while retaining a relative accuracy of ∼0.1%. Our approach is quite general and can readily be adapted to other simulation methods.
On the wake structure of a micro-ramp vortex generator in hypersonic flow
Authors: Sun Dong , Chen Jianqiang , Li Chen , Liu Pengxin , Guo Qilong , Yuan Xianxu
Published: December 2020

In this paper, a direct numerical simulation is performed to study the wake structures of a micro-ramp vortex generator in the hypersonic flow. The whole evolution process of vortical structures of the wake flow has been carefully analyzed. First, the scaling laws for the profiles of mean velocities and fluctuations have been explored. The results show that the scaling laws based on the supersonic experiments can be directly applied in the hypersonic wake flow with a few discrepancies near the wall. Then, the detailed structures of arc-like vortices are examined, and the legs of vortices are found not being connected with each other. No full vortex ring is detected in the present simulation. At the downstream of the wake flow, the intensity of arc-like vortices has been augmented when passing the separation shock. The results reveal that a vortex train composed of arc-like vortices and shear layer is formed. With the help of the proper orthogonal decomposition, the impact of arc-like vortices on the heat flux has been revealed. The alternative positive and negative strips in the streamwise direction suggest the impinging process of arc-like vortices. The frequencies of the corresponding modes further prove that the strips are the footprint of arc-like vortices.
Effect of dielectric barrier discharge plasma actuators on vortical structures in a mixing layer
Authors: Yadala Srikar , Benard Nicolas , Kotsonis Marios , Moreau Eric
Published: December 2020

The influence of spanwise-uniform electro-fluid-dynamic forcing applied by a dielectric barrier discharge (DBD) plasma actuator on the growth of a plane mixing layer and the dynamics of large-scale spanwise vortices are investigated experimentally. A two-dimensional mixing layer formed between two streams of air with different velocities is employed for this study. Quantitative spatio-temporal measurement of the flow field is acquired using high-speed planar particle image velocimetry. The DBD actuator was constructed such that it imparts perturbations into the splitter-plate boundary layer formed by the high-velocity fluid stream, close to the trailing edge. Through this, the fundamental Kelvin–Helmholtz instability of the current mixing layer and its first sub-harmonic are forced. Forcing the fundamental instability results in the inhibition of vortex pairing due to the attenuation of sub-harmonic instabilities, and thus, mixing layer growth is halted in the vicinity of the trailing edge. With sub-harmonic instability forcing, neighboring vortices interact with each other and amalgamate together through mutual induction. This results in a higher growth rate compared to the unforced mixing layer at the streamwise location of this vortex interaction. Eventually, the growth rate of the forced mixing layers becomes similar to that of the unforced case. These results demonstrate the influence of the applied forcing on the spectral signature, growth, and stability characteristics of the plane mixing layer and the dynamics of the coherent vortical structures.
An insulating doped antiferromagnet with low magnetic symmetry as a room temperature spin conduit
Authors: Ross Andrew , Lebrun Romain , Baldrati Lorenzo , Kamra Akashdeep , Gomonay Olena , Ding Shilei , Schreiber Felix , Backes Dirk , Maccherozzi Francesco , Grave Daniel A. , Rothschild Avner , Sinova Jairo , Kläui Mathias
Published: December 2020

We report room-temperature long-distance spin transport of magnons in antiferromagnetic thin-film hematite doped with Zn. The additional dopants significantly alter the magnetic anisotropies, resulting in a complex equilibrium spin structure that is capable of efficiently transporting spin angular momentum at room temperature without the need for a well-defined, pure easy-axis or easy-plane anisotropy. We find intrinsic magnon spin-diffusion lengths of up to 1.5 μm, and magnetic domain governed decay lengths of 175 nm for the low-frequency magnons, through electrical transport measurements demonstrating that the introduction of nonmagnetic dopants does not strongly reduce the transport length scale, showing that the magnetic damping of hematite is not significantly increased. We observe a complex field dependence of the nonlocal signal independent of the magnetic state visible, in the local magnetoresistance and direct magnetic imaging of the antiferromagnetic domain structure. We explain our results in terms of a varying and applied field-dependent ellipticity of the magnon modes reaching the detector electrode allowing us to tune the spin transport.
Assessment of the Wolf method using the Stillinger–Lovett sum rules: From strong electrolytes to weakly charged colloidal dispersions
Authors: Falcón-González José Marcos , Contreras-Aburto Claudio , Lara-Peña Mayra , Heinen Marco , Avendaño Carlos , Gil-Villegas Alejandro , Castañeda-Priego Ramón
Published: December 2020

The Ewald method has been the cornerstone in molecular simulations for modeling electrostatic interactions of charge-stabilized many-body systems. In the late 1990s, Wolf and collaborators developed an alternative route to describe the long-range nature of electrostatic interactions; from a computational perspective, this method provides a more efficient and straightforward way to implement long-range electrostatic interactions than the Ewald method. Despite these advantages, the validity of the Wolf potential to account for the electrostatic contribution in charged fluids remains controversial. To alleviate this situation, in this contribution, we implement the Wolf summation method to both electrolyte solutions and charged colloids with moderate size and charge asymmetries in order to assess the accuracy and validity of the method. To this end, we verify that the proper selection of parameters within the Wolf method leads to results that are in good agreement with those obtained through the standard Ewald method and the theory of integral equations of simple liquids within the so-called hypernetted chain approximation. Furthermore, we show that the results obtained with the original Wolf method do satisfy the moment conditions described by the Stillinger–Lovett sum rules, which are directly related to the local electroneutrality condition and the electrostatic screening in the Debye–Hückel regime. Hence, the fact that the solution provided by the Wolf method satisfies the first and second moments of Stillinger–Lovett proves, for the first time, the reliability of the method to correctly incorporate the electrostatic contribution in charge-stabilized fluids. This makes the Wolf method a powerful alternative compared to more demanding computational approaches.
Identifying physiological and environmental influences on otolith chemistry in a coastal fishery species
Authors: Martino Jasmin C. , Doubleday Zoë A. , Fowler Anthony J. , Gillanders Bronwyn M.
Published: December 2020

Otolith (ear stone) chemistry provides powerful insights into the lives of fish. Although frequently used to reconstruct past environments, the influence of physiology remains unsettled. As such, we investigated the relationships between otolith chemistry, physiological factors and environmental factors in an iconic fishery species, snapper (Chrysophrys auratus). Lifetime otolith profiles were analysed of carbon (δ13C) and oxygen (δ18O) isotopes, and elemental concentrations of lithium (Li:Ca), magnesium (Mg:Ca), manganese (Mn:Ca), strontium (Sr:Ca), and barium (Ba:Ca). Mixed-effects modelling alongside a detailed literature review was used to investigate physiological (age, otolith growth rate, fish size, sex) and environmental influences (sea-surface temperature and chlorophyll-a) on otolith chemistry. Carbon isotopes and magnesium related to physiological factors, suggesting their potential as physiological proxies. Physiology also weakly related to strontium and lithium. By contrast, oxygen isotopes, barium, and manganese (except for natal signatures) were suggested to provide insights into past environments. Our study stresses the importance of consistency in biological characteristics for study designs, and highlights the potential of physiological proxies for distinguishing between populations in uniform water bodies. This study has not only reinforced our confidence in field applications of otolith chemistry, but has furthered our understanding of the influence of physiology.
Pollution and health risk assessment of heavy metals in soils of Guizhou, China
Authors: Yu Gao , Chen Fen , Zhang Hongli , Wang Zuhua
Published: December 2020

Mining of minerals in Guizhou, China, where it is enriched with reserves, may lead to soil contamination with heavy metals. We assessed the risk of eight typical heavy metals in Guizhou soils by collecting province-wide data available in the literature and using the geo-accumulation index method, the ecological risk assessment method, and the USEPA health risk assessment model. The concentrations of eight heavy metals, except for Pb and Cr, were above the background levels. Soil heavy metal pollution evaluation results showed that As, Cu, Zn, Pb, Cr, Cd, and Ni reached the pollution levels, while Hg fell into the category of moderate contamination. As, Cu, Zn, Pb, Cr, and Ni posed low potential ecological risk, while Cd and Hg demonstrated a considerable or a very high potential ecological risk. Totally, the integrated potential ecological risk was ranked “very high” . Regarding to health risk, the non-carcinogenic risks caused by heavy metals were insigniﬁcant, but the carcinogenic risk caused by As was signiﬁcant. Consequently, there appeared serious soil contamination of Hg and As, with the latter also being the greatest potential risk to human health. Both Hg and As should stay at the highest priory for remediation efforts in Guizhou soils.
Black hole collapse and bounce in effective loop quantum gravity
Authors: Kelly Jarod George , Santacruz Robert , Wilson-Ewing Edward
Published: December 2020

We derive effective equations with loop quantum gravity corrections for the Lemaître–Tolman–Bondi family of space-times, and use these to study quantum gravity effects in the Oppenheimer–Snyder collapse model. For this model, after the formation of a black hole with an apparent horizon, quantum gravity effects become important in the space-time region where the energy density and space-time curvature scalars become comparable to the Planck scale. These quantum gravity effects first stop the collapse of the dust matter field when its energy density reaches the Planck scale, and then cause the dust field to begin slowly expanding. Due to this continued expansion, the matter field will eventually extend beyond the apparent horizon, at which point the horizon disappears and there is no longer a black hole. There are no singularities anywhere in this space-time. In addition, in the limit that edge effects are neglected, we show that the dynamics for the interior of the star of uniform energy density follow the loop quantum cosmology effective Friedman equation for the spatially flat Friedman–Lemaître–Robertson–Walker space-time. Finally, we estimate the lifetime of the black hole, as measured by a distant observer, to be ∼(GM)2/ℓ
Pl.
A transgenic genetic algorithm design method that helps to increase the design freedom of metasurfaces
Authors: Yuan Qi , Ma Hua , Sui Sai , Wang Jiafu , Meng Yueyu , Pang Yongqiang , Qu Shaobo
Published: December 2020

While the optimization of design is an effective way to increase the performance of metasurfaces, there is still much to be done to improve optimization algorithms. In this work, a transgenic genetic algorithm (TGA) proposed for metasurface design offers higher performance and more design freedom. Based on GAs, transgenic technology is introduced into metasurface design to improve both performance and flexibility. We describe the generation of a transgenic factor (TF), how it operates on metasurface design, and explain the feasibility of enhancing design freedom using a TGA. To target the broadband regime and high efficiency, an electromagnetic polarization converter and an absorber are then designed by TGA, respectively. As a result, polarization conversion of more than −1 dB and absorption of over 90% were achieved from 8.09 GHz to 24.90 GHz and 7.71 GHz to 20.01 GHz, respectively. Both simulated and measured results are highly consistent, which validates the stable performance achieved by the proposed TGA design. What is more, a performance comparison between different TFs illustrates the subtle influence of TFs, revealing that the performance is improved to some extent by an increase of surface-design freedom. Significantly, this effort provides more freedom in the design method, leading to the realization of many expected improvements.
Dynamics of polystyrene probed by muon spin spectroscopy
Authors: McKenzie Iain , Cordoni-Jordan Danaan , Cannon Joseph , Cottrell Stephen P
Published: December 2020

Muon spin spectroscopic measurements were made on atactic low-molecular-weight (LMW) (1.3 kg mol−1) and high-molecular-weight (HMW) (202 kg mol−1) polystyrene. Muoniated cyclohexadienyl radicals, which are formed by muonium addition to the phenyl side groups, are used as local probes of bulk dynamics. Muon spin relaxation is caused by the secondary γ-relaxation process, which involves motion of the phenyl rings, and is sensitive to the glass transition. The activation energy of the γ-relaxation process in the rubbery state is 0.60(2) eV in the HMW sample and 0.37(3) eV in the LMW sample.
First-principles discovery of stable two-dimensional materials with high-level piezoelectric response
Authors: Kocabaş Tuğbey , Çakır Deniz , Sevik Cem
Published: December 2020

The rational design of two-dimensional (2D) piezoelectric materials has recently garnered great interest due to their increasing use in technological applications, including sensor technology, actuating devices, energy harvesting, and medical applications. Several materials possessing high piezoelectric response have been reported so far, but a high-throughput first-principles approach to estimate the piezoelectric potential of layered materials has not been performed yet. In this study, we systematically investigated the piezoelectric (e
11, d
11) and elastic (C11 and C12) properties of 128 thermodynamically stable 2D semiconductor materials by employing first-principle methods. Our high-throughput approach demonstrates that the materials containing Group-V elements produce significantly high piezoelectric strain constants, d
11 > 40 pm V−1, and 49 of the materials considered have the e
11 coefficient higher than MoS2 insomuch as BrSSb has one of the largest d
11 with a value of 373.0 pm V−1. Moreover, we established a simple empirical model in order to estimate the d
11 coefficients by utilizing the relative ionic motion in the unit cell and the polarizability of the individual elements in the compounds.
Tailoring the structure of MoS2 using ball-milled MoO3 powders: hexagonal, triangular, and fullerene-like shapes
Authors: Jiménez-Ramírez Luis E , Muñoz-Sandoval Emilio , López-Urías Florentino
Published: December 2020

Single and few-layered MoS2 materials have attracted attention due to their outstanding physicochemical properties with potential applications in optoelectronics, catalysis, and energy storage. In the past, these materials have been produced using the chemical vapor deposition (CVD) method using MoO3 films and powders as Mo precursors. In this work, we demonstrate that the size and morphology of few-layered MoS2 nanostructures can be controlled, modifying the Mo precursor mechanically. We synthesized few-layered MoS2 materials using MoO3 powders previously exposed to a high-energy ball milling treatment by the salt-assisted CVD method. The MoO3 powders milled for 30, 120, and 300 min were used to synthesize sample MoS2-30, MoS2-120, and MoS2-300, respectively. We found morphologies mainly of hexagons (MoS2-30), triangles (MoS2-120), and fullerenes (MoS2-300). The MoS2 nanostructures and MoO3 powders were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, x-ray diffraction, and thermogravimetric analysis. It was found that MoO3 milled powders exhibit oxygen loss and decrease in crystallite size as milling time increases. Oxygen deficiency in the Mo precursor prevents the growth of large MoS2 crystals and a large number of milled MoO3-x
 + NaCl promote greater nucleation sites for the formation of MoS2, achieving a high density of nanoflakes in the 2H and 3R phases, with diameter sizes in the range of ∼30–600 nm with 1–12 layers. Photoluminescence characterization at room temperature revealed a direct bandgap and exciting trends for the different MoS2 samples. We envisage that our work provides a route for modifying the structure and optical properties for future device design via precursor engineering.
Potential anticancer activity of a new pro-apoptotic peptide–thioctic acid gold nanoparticle platform
Authors: Akrami Mohammad , Samimi Shabnam , Alipour Mohsen , Bardania Hassan , Ramezanpour Sorour , Najafi Niayesh , Hosseinkhani Saman , Kamankesh Mojtaba , Haririan Ismaeil , Hassanshahi Fatemeh
Published: December 2020

Targeted nanoparticle platforms designed to induce cell death by apoptosis can bypass the resistance mechanisms of cancer cells. With this in mind we have constructed a new cancer-targeting peptide-functionalized nanoparticle using gold nanoparticles (AuNPs) and a thioctic acid–DMPGTVLP peptide (TA-peptide) conjugate. Morphological analysis of the nanoparticles by transmission electron microscopy showed average diameters of about 3.52 nm and 26.2 nm for the AuNP core and shell, respectively. Strong affinity toward the nucleolin receptors of breast cancer cell lines MCF-7 and T47D was observed for the TA-peptide gold nanoparticles (TAP@AuNPs) based on IC50 values. Furthermore, the nanoparticles showed excellent hemocompatibility. Quantitative results of atomic absorption showed improved uptake of TAP@AuNPs. Treatment of the cells with TAP@AuNPS resulted in greater release of cytochrome c following caspase-3/7 activation compared with free TA-peptide. The cytosolic level of adenosine triphosphate for TAP@AuNPs was higher than in controls. Higher anti-tumor efficiency was observed for TAP@AuNPs than TA-peptide compared with phosphate-buffered saline after intratumoral injection in tumor-bearing mice. It can be concluded that the design and development of a receptor-specific peptide-AuNP platform will be valuable for theranostic applications in cancer nanomedicine.