bluuebunny/crossref_metadata_2025 huggingface dataset:
2D phononic-crystal Luneburg lens for all-angle underwater sound localization
Authors: Ruan Yongdu , Liang Xu
Published: April 2022

Phononic crystals are well known for acoustic wave manipulation which may have potential application in an underwater acoustic detection system. In this work, we design and simulate a two-dimensional Luneburg lens based on gradient-index (GRIN) phononic crystal that is composed of PLA-Air inclusion, and a novel application of GRIN phononic crystals is proposed to sound localization. The Luneburg lens has a broadband working range, from 1500 Hz to 7500 Hz, for acoustic wave focusing with sensitive directivity and signal-to-noise improvement. By searching maximum wave intensity’s position of the focusing beam, the propagating direction of an unknown sound wave can be directly recognized covering 360°. Besides, we redesign the conventional square-lattice Luneburg lenses using annular lattices for better performance. The annular-lattice Luneburg lens overcomes the weakness of configuration defect due to the square lattice. The numerical results show that the redesign Luneburg lenses have high accuracy for distance measurement from 5 m to 35 m through the triangulation location. In a word, this work tries to explore a novel application of phononic crystals in underwater acoustic positioning and navigation technology.
Clinical and cytological findings in oral cavity of young shisha smokers and non-smokers – a comparative study
Authors: Ramamurthy Priyadarshini Hesarghatta , Fernandes Bennete Aloysius , Tegginamani Anand S. , Rath Avita , Sidhu Preena , Bin Zamzuri Ahmad Termizi
Published: April 2022

Introduction: Shisha, a form of smoking tobacco is known to be detrimental to oral health. Yet, the effects of shisha on oral health is not well documented. Hence, this study was undertaken to compare the clinical and cytological findings in oral cavity of young shisha smokers as compared to non-smokers. Materials and methods: A cross-sectional analytical study was undertaken among 60 subjects including 30 young shisha smokers and 30 non-smokers. Clinical examination was carried out to record gingival status, periodontal status, oral hygiene and dental caries experience. Exfoliative cytology was used to study the cytological changes of buccal mucosal cells. Data was analysed using SPSS version 22. Student’s t-test, Fisher’s exact test and odd’s ration was used for comparison. p < 0.05 was considered statistically significant. Results: No significant differences were found between the groups with respect to proportion of subjects with gingivitis (p = 0.071), erosion (p = 0.085) and dental caries experience (p = 0.329). However, shisha smokers had poorer oral hygiene and more severe gingival inflammation as compared to non-smokers with p = 0.026 and p = 0.007 respectively. The odds of having atypical cells in oral mucosa among shisha smokers was 3.76 times higher than the non-smokers. Conclusion: The findings of our study showed that young shisha smokers had more atypical cells in oral mucosa as compared to their non-smoking counterparts. However, longitudinal studies are needed to affirm the findings of this study.
Evaluation and Treatment of Severe Hyperacusis
Authors: Valente Michael , Goebel Joel , Duddy Diane , Sinks Belinda , Peterein Judy
Published: April 2022

A 52-year-old male was evaluated by the authors after initially reporting fullness in his left ear while traveling on an airplane. A unique feature of the patient's complaint was the development of severe bilateral hyperacusis (loudness discomfort levels of between 20–34 dB HL) in spite of the fact that the hearing loss was initially reported in the left ear. To achieve loudness comfort, the patient was initially fit with ER-25 musician earplugs that proved to be unsuccessful. The patient next purchased earplugs and earmuffs from a gun shop in order to obtain relief from the pain and discomfort caused by his exposure to everyday environmental sounds. This paper describes the use of hearing devices that proved to be effective in providing attenuation sufficient that the patient rarely needs to rely on earplugs and ear-muffs for relief from his hyperacusis.

Abbreviations: CBC = complete blood count, ESR = erythrocyte sedimentation rate, LDL= loudness discomfort level
Adaptation to Loudness and Environmental Stimuli in Three Newly Fitted Hearing Aid Users
Authors: Lindley George A. , Palmer Catherine V. , Durrant John , Pratt Sheila
Published: April 2022

Hearing aid fitting strategies can be categorized according to whether a loudness normalization or a loudness equalization rationale is employed. Regardless of the underlying rationale, the amount of patient participation in determining the initial hearing aid settings will vary when an audiologist-driven (AD) versus a patient-driven protocol is employed. When an AD protocol is used, few changes are made during the initial fitting session based on user feedback. It is assumed that the patient will adapt to the loudness and/or sound quality provided by the hearing aids if not immediately acceptable. The following three case reports document varying degrees of adaptation to hearing aid settings derived using an AD approach. Clinical implications will be discussed.

Abbreviations: AD = audiologist driven, DSL [i/o] = Desired Sensation Level input/output, EN = environmental noise subscale, HINT = Hearing in Noise Test, IHAFF = Independent Hearing Aid Fitting Forum, LE = loudness equalization, LN = loudness normalization, PD = patient driven, PHAP = Profile of Hearing Aid Performance, RAB = Ricketts and Bentier, SII = Speech Intelligibility Index, WDRC = wide dynamic range compression
Cisplatin Ototoxicity, Increased DPOAE Amplitudes, and Magnesium Deficiency
Authors: Cevette Michael J. , Drew Danielle , Webb Teresa M. , Marion Mitchell S.
Published: April 2022

Outer hair cell (OHC) metabolism is blocked by cisplatin. Concurrent changes in the renal handling of magnesium occur because of the damage cisplatin causes to the renal proximal tubule cells within the thick ascending loop of Henle. Although there is no evidence of cisplatin within the OHCs, there are significant levels of intracellular calcium, the antagonist to magnesium at the cell membrane. The OHC motile response is dependent on intracellular calcium. When the calcium current is suppressed by an antagonist, the extracellular OHC microphonic potential decreases. Magnesium deficiency is known to produce hyperexcitabililty within the central nervous system, including fatal audiogenic seizures. In addition, increases in the amplitude of the auditory brainstem response wave V occur with aminoglycoside therapy and magnesium deficiency. This paper illustrates the amplitude growth of distortion product otoacoustic emissions in two patients treated with cisplatin and explores the possible underlying reasons why this may be related to magnesium metabolism.

Abbreviations: DPOAEs = distortion product otoacoustic emissions, OAEs = otoacoustic emissions, OHC = outer hair cell, TEOAEs = transient otoacoustic emissions
Einrichtungsbezogene Impfpflicht: Wer, wann, was, wohin …
Authors: Hesser Alexandra
Published: April 2022

Seit 16. März gilt die einrichtungsbezogene Impfpflicht. Bis 31. März mussten alle Beschäftigten im Gesundheitswesen, die bis zum Stichtag noch nicht über einen vollständigen Impfschutz oder ein Genesenenattest verfügt haben, an die zuständigen Gesundheitsämter gemeldet werden. Immer noch ist die Lage in Deutschland uneinheitlich. Zum Versorgungskollaps kam es bislang nicht.
Erste Ergebnisse des Digitalradar: „Solide“ Digitalisierung in den Kliniken
Authors: Hesser Alexandra
Published: April 2022

Mit dem Krankenhauszukunftsgesetz (KHZG) fließen 4,3 Milliarden Euro in die Förderung der digitalen Infrastruktur der Krankenhäuser. Daher sieht das Gesetz eine „Analyse und Bewertung“ der digitalen Reife in deutschen Krankenhäusern vor. Die erste Online-Erhebung durch das Projekt „Digitalradar“ endete kurz vor Weihnachten. Nun liegen erste Ergebnisse vor, sie fallen gemischt aus.
A relational view on the performance effects of international diversification strategies
Authors: Yildiz H. Emre , Morgulis-Yakushev Sergey , Holm Ulf , Eriksson Mikael
Published: April 2022

International diversification is a fundamental pillar of multinational corporations’ (MNCs) growth strategies. Consequently, there is a considerable body of research on the performance implications of MNCs’ international diversification strategies. We extend this literature by adopting a relational view where we compare the diversification profiles of firms in an inter-organizational context. We argue that the relative characteristics of firms’ and their partners’ diversification profiles is an indicator of parties’ resource bases and thereby can explain if and when inter-organizational ties yield optimum performance outcomes. We examine these relative characteristics and propose a conceptual refinement by differentiating between the degree and content dimensions of international diversification. Analyzing data from 202 manufacturing firms from the S&P 500 list, we find that firms achieve optimum performance when their partners have moderately higher degrees of international diversification and a moderate overlap of presence in foreign markets.
20th Century revolutions: characteristics, types, and waves
Authors: Grinin Leonid , Grinin Anton , Korotayev Andrey
Published: April 2022

The 20th century revolutionary process had a big impact on the World System and significantly changed its entire configuration. However, there are essential gaps in terms of theoretical approaches, in particular, in terms of the typology of revolutions. Moreover, there is clearly insufficient research related to qualitative and quantitative analysis and consideration of the revolutions of the 20th century in their entirety. This article aims to fill those gaps by pursuing three main goals: (1) comparison of revolutions of the 20th and 19th centuries, highlighting the important characteristics of the former; (2) classification of revolutions of the 20th century; (3) identification of the main revolutionary waves of the 20th century and their essential characteristics.
Challenges in large-scale bioinformatics projects
Authors: Morrison-Smith Sarah , Boucher Christina , Sarcevic Aleksandra , Noyes Noelle , O’Brien Catherine , Cuadros Nazaret , Ruiz Jaime
Published: April 2022

Biological and biomedical research is increasingly conducted in large, interdisciplinary collaborations to address problems with significant societal impact, such as reducing antibiotic resistance, identifying disease sub-types, and identifying genes that control for drought tolerance in plants. Many of these projects are data driven and involve the collection and analysis of biological data at a large-scale. As a result, life-science projects, which are frequently diverse, large and geographically dispersed, have created unique challenges for collaboration and training. We examine the communication and collaboration challenges in multidisciplinary research through an interview study with 20 life-science researchers. Our results show that both the inclusion of multiple disciplines and differences in work culture influence collaboration in life science. Using these results, we discuss opportunities and implications for designing solutions to better support collaborative tasks and workflows of life scientists. In particular, we show that life science research is increasingly conducted in large, multi-institutional collaborations, and these large groups rely on “mutual respect” and collaboration. However, we found that the interdisciplinary nature of these projects cause technical language barriers and differences in methodology affect trust. We use these findings to guide our recommendations for technology to support life science. We also present recommendations for life science research training programs and note the necessity for incorporating training in project management, multiple language, and discipline culture.
Sharp complexity asymptotics and topological trivialization for the (p, k) spiked tensor model
Authors: Auffinger Antonio , Ben Arous Gerard , Li Zhehua
Published: April 2022

Using precise random matrix theory tools and the Kac–Rice formula, we provide sharp O(1) asymptotics for the average number of deep minima of the (p, k) spiked tensor model. These sharp estimates allow us to prove that, when the signal-to-noise ratio is large enough, the expected number of deep minima is asymptotically finite as N tends to infinity and to establish the occurrence of topological trivialization by showing that this number vanishes when the strength of the signal-to-noise ratio diverges. We also derive an explicit formula for the value of the absolute minimum (the limiting ground state energy) on the N-dimensional sphere, similar to the recent work of Jagannath, Lopatto, and Miolane [Ann. Appl. Probab. 4, 1910–1933 (2020)].
Tunable photonic bandgap and reflection phase shift properties of 1D binary photonic crystal consisting of double negative and magnetic cold plasma materials
Authors: Kumari Nitu , Varshney Anshu D. , Awasthi Suneet K. , Shiveshwari Laxmi , Aly Arafa H.
Published: April 2022

In this manuscript, by using alternate layers of double negative and magnetic cold plasma materials, we have studied the reflection and reflection phase shift properties of 1D binary photonic crystals. The simulations of the proposed work have been carried out by using the transfer matrix method with the help of MATLAB software. It has been found that the combination of the angle of incidence and external magnetic field under both right hand polarized and left handed polarized configurations can be used for right and left tuning of photonic bandgap (PBG) of the proposed structure under consideration. Under the aforementioned circumstances, the reflection phase shift corresponding to TE and TM waves can be smoothly switched between 0 to π and –π to 0, respectively, across PBGs of the proposed structure. The variation in external magnetic field values from 0 to 6 T and angle of incidence from 0° to 80° can be used for precise tuning of PBG and reflection phase shift between –π and π depending upon TM and TE polarization cases, respectively. This study may open a new gateway for designing externally tunable microwave devices like single to multichannel band-stop filters, buffers that can hold data temporarily, tunable wave plates, and tunable phase retarders.
Background energy spectra for LSO/LYSO scintillation crystals of different geometries
Authors: Alva-Sánchez Héctor
Published: April 2022

The background energy spectrum of lutetium oxyorthosilicate/lutetium yttrium oxyorthosilicate scintillation crystals used in positron emission imaging systems is a research topic of great interest owing to the possibility of using its structure to perform detector calibration and quality control without the need of using external radiation sources. In this paper, the background energy spectra for crystals of different sizes and geometries, including cuboids, frusta, cylinders, tetrahedra, and spheres, have been computed. This was done using a previously developed analytical model that requires the photon absorption probabilities for each shape, obtained through simulations using the PENELOPE Monte Carlo code. It has been found that crystals of different geometries, but with the same volume-to-surface area ratio, give rise to very similar background energy spectra, simplifying its computation. In addition, simple ray tracing simulations were performed, and a robust geometrical model was devised to investigate the geometrical grounds of this practical and compelling result.
Double crossing conical intersections and anti-Vavilov fluorescence in tetraphenyl ethylene
Authors: Hou Zhuowei , Guan Jianxin , Peng Jie , Li Xinmao , Yu Zhihao , Zheng Junrong
Published: April 2022

Conical intersections (CIs) provide effective fast nonradiative decay pathways for electronic excitation, which can significantly influence molecular photoluminescence properties. However, in many cases, crossing a CI does not have direct observables, making studies of CIs experimentally challenging. Herein, the theoretically predicted double CIs by cis–trans twisting and cyclization in tetraphenyl ethylene, a well-known aggregation-induced emission molecule, are investigated with excitation dependent ultrafast UV/IR spectroscopy and fluorescence. Both the fluorescence quantum yield and the efficiency of cyclization are found to be smaller with a shorter excitation wavelength. An abrupt change occurs at about 300–310 nm. The results imply that crossing the twisting CI has a larger barrier than the cyclization CI, and the cis–trans twisting motion is probably involved with large solvation reorganization.
Influence of electron energy distribution on fluid models of a low-pressure inductively coupled plasma discharge
Authors: Levko Dmitry , Upadhyay Rochan R. , Raja Laxminarayan L. , Ranjan Alok , Ventzek Peter
Published: April 2022

The aim of the present paper is to examine the influence of assumption on the electron energy distribution function on the relation between the plasma potential and the electron temperature for both electropositive (argon) and electronegative (chlorine) plasmas. A one-dimensional fluid model is used for simplicity although similar results were obtained using a self-consistent two-dimensional fluid model coupled with the Maxwell's equations for inductively coupled plasmas. We find that for electropositive plasma only a bi-Maxwellian electron energy distribution function provides reasonable results compared to measurements in low-pressure inductively coupled plasmas, namely, the increasing plasma potential for increasing electron temperature. For electronegative plasma, the plasma potential is an increasing function of the electron temperature for all electron distributions considered in the model. However, the scaling factors do not agree with the conventional plasma theory. We explain these results by the deviation of electrons from a Boltzmann distribution, which is due to non-equilibrium and non-local nature of plasma at the low-pressure conditions.
Correlation between d-orbital bandwidth and local coordination environment in RE2SiO5 compounds with implications in minimizing the coefficient of thermal expansion anisotropy (RE = Sc, Y, La)
Authors: Ayyasamy Mukil V. , Balachandran Prasanna V.
Published: April 2022

Y2SiO5 is one of the promising environmental barrier coating (EBC) materials that protect the gas turbine engine components from unfavorable reactions at higher temperatures. The Y2SiO5 compound forms in the monoclinic crystal structure (C2/c space group), and one of the drawbacks is its appreciable coefficient of thermal expansion (CTE) anisotropy, which adversely affects its lifetime as the EBC material. The objective of this work is to uncover previously unknown correlation between the electronic structure and crystal structure of RE2SiO5 compounds in the equilibrium and hypothetical C2/c structures (where RE = Sc, Y, or La). Our density functional theory calculations reveal a trend in the RE-cation d-orbital bandwidth as a function of the RE electronic configuration, local RE–O coordination environment, and unit cell volume. We predict that the Y-4d orbital bandwidth can become narrower when Y2SiO5 forms in an open structure with a reduced Y–O effective coordination number. We conjecture that a narrow Y-4d orbital bandwidth may give rise to smaller CTE anisotropy compared to Y2SiO5 in its equilibrium structure. The outcome of this work has potential implications in the rational design of Y2SiO5-based EBCs for use under extreme temperature environments.
Use of a non-collinear wave mixing technique to image internal microscale damage in concrete
Authors: Kim Jin-Yeon , Bellotti Aurelio , Alapati Prasanth , Kurtis Kimberly E. , Qu Jianmin , Jacobs Laurence J.
Published: April 2022

This research demonstrates the feasibility of using a non-collinear wave mixing technique to image internal microscale damage throughout the interior volume of a relatively large (28 cm thick) concrete component. By exploiting the underlying mechanics of nonlinear wave mixing, it is possible to mix two incident waves with frequencies low enough to propagate without being scattered by the inherently heterogenous, concrete microstructure, while still being sensitive to damage features with length scales well below these incident wavelengths. For this study, scanning and imaging is accomplished by manually adjusting the locations of the two incident waves, while a knowledge of the wave speeds in concrete plus synchronization identifies the location of the mixing zone—the specific volume of concrete being imaged. The viability of the proposed technique is demonstrated by examining a concrete prism specimen with known, embedded internal microscale damage.
Hydrodynamic and heat transfer aspects of low Peclet gaseous flows through an isothermally heated pipe
Authors: Jha Ambuj Amitab , Agrawal Amit
Published: April 2022

For the gaseous flow applications involving axial diffusion of heat, the hydrodynamic and thermal aspects get erroneously predicted if the conventional extended Graetz problem is attended. The present work highlights such deviations of the flow field and the respective derived parameters under the influence of axial conduction and radial advection with the variation of thermophysical properties retained. The complete transport equations are numerically solved for the low Peclet (Pe) gaseous flows through a circular pipe for the Pe and wall temperature in the ranges [1–100] and [350–1200 K], respectively. The results are validated for the conventional case of the extended Graetz problem with its conditional assumptions. For the general case, it is observed that the required pipe length is overpredicted when the property variation is not accounted for. The rising wall temperature tends to shift the whole non-isothermal region upstream that we tabulate for its extreme ends for the limiting cases. The spatially varying strength of diffusion and advection bring in the non-parabolic and non-self-similar velocity profile that reports sheer dependence on the supplied heat. The Nusselt number is seen to drop to a minimum before increasing to the asymptotic value, and the respective axial locations are found to be varying with Pe and the supplied heat.
High-energy-density metal nitrides with armchair chains
Authors: Yuan Jianan , Xia Kang , Ding Chi , Wang Xiaomeng , Lu Qing , Sun Jian
Published: April 2022

Polymeric nitrogen has attracted much attention owing to its possible application as an environmentally safe high-energy-density material. Based on a crystal structure search method accelerated by the use of machine learning and graph theory and on first-principles calculations, we predict a series of metal nitrides with chain-like polynitrogen (P21-AlN6, P21-GaN6, P-1-YN6, and P4/mnc-TiN8), all of which are estimated to be energetically stable below 40.8 GPa. Phonon calculations and ab initio molecular dynamics simulations at finite temperature suggest that these nitrides are dynamically stable. We find that the nitrogen in these metal nitrides can polymerize into two types of poly-N42− chains, in which the π electrons are either extended or localized. Owing to the presence of the polymerized N4 chains, these metal nitrides can store a large amount of chemical energy, which is estimated to range from 4.50 to 2.71 kJ/g. Moreover, these compounds have high detonation pressures and detonation velocities, exceeding those of conventional explosives such as TNT and HMX.
Atomic-resolved structural and electric field analysis of the passivation interface of MIS-HEMTs
Authors: Zhang Jiahui , Su Xujun , Cai Yutao , Li Didi , Wang Luhua , Chen Jingjing , Zeng Xionghui , Wang Jianfeng , Xu Ke
Published: April 2022

The passivation interfaces of GaN-based MIS-HEMTs with Si3N4 and ZrO2/Si3N4 bilayers were investigated through atomic resolution scanning transmission electron microscope–energy dispersive spectroscopy–differential phase contrast microscopy methods. It is found that the Si3N4/GaN interface exhibits atomic disorder fluctuation, and the GaN surface is discontinuous at the depth of 1–2 atomic layers. An oxide layer of ∼2 nm is formed at the ZrO2/GaN interface, and the GaN surface is atomically flat. Furthermore, the local minimum of the potential is located at the Si3N4/GaN interface, while it is distributed in the GaN side at the ZrO2/GaN interface. The electric field or potential distribution is affected by the crystal orientation of the polycrystalline ZrO2 layer. Finally, the difference in passivation mechanism is discussed.
Electron-induced fragmentation of water droplets: Simulation study
Authors: Suchan Jiří , Kolafa Jiří , Slavíček Petr
Published: April 2022

The transport of free electrons in a water environment is still poorly understood. We show that additional insight can be brought about by investigating fragmentation patterns of finite-size particles upon electron impact ionization. We have developed a composite protocol aiming to simulate fragmentation of water clusters by electrons with kinetic energies in the range of up to 100 eV. The ionization events for atomistically described molecular clusters are identified by a kinetic Monte Carlo procedure. We subsequently model the fragmentation with classical molecular dynamics simulations, calibrated by non-adiabatic quantum mechanics/molecular mechanics simulations of the ionization process. We consider one-electron ionizations, energy transfer via electronic excitation events, elastic scattering, and also the autoionization events through intermolecular Coulombic decay. The simulations reveal that larger water clusters are often ionized repeatedly, which is the cause of substantial fragmentation. After losing most of its energy, low-energy electrons further contribute to fragmentation by electronic excitations. The simultaneous measurement of cluster size distribution before and after the ionization represents a sensitive measure of the energy transferred into the system by an incident electron.
Thermodynamics of electrolyte solutions near charged surfaces: Constant surface charge vs constant surface potential
Authors: Bruch Dorian , Balzer Christopher , Wang Zhen-Gang
Published: April 2022

Electric double layers are ubiquitous in science and engineering and are of current interest, owing to their applications in the stabilization of colloidal suspensions and as supercapacitors. While the structure and properties of electric double layers in electrolyte solutions near a charged surface are well characterized, there are subtleties in calculating thermodynamic properties from the free energy of a system with charged surfaces. These subtleties arise from the difference in the free energy between systems with constant surface charge and constant surface potential. In this work, we present a systematic, pedagogical framework to properly account for the different specifications on charged bodies in electrolyte solutions. Our approach is fully variational—that is, all free energies, boundary conditions, relevant electrostatic equations, and thermodynamic quantities are systematically derived using variational principles of thermodynamics. We illustrate our approach by considering a simple electrolyte solution between two charged surfaces using the Poisson–Boltzmann theory. Our results highlight the importance of using the proper thermodynamic potential and provide a general framework for calculating thermodynamic properties of electrolyte solutions near charged surfaces. Specifically, we present the calculation of the pressure and the surface tension between two charged surfaces for different boundary conditions, including mixed boundary conditions.
Quasielastic neutron scattering reveals the temperature dependent rotational dynamics of densely grafted oleic acid
Authors: Sharma Aakash , Kruteva Margarita , Zamponi Michaela , Ehlert Sascha , Richter Dieter , Förster Stephan
Published: April 2022

We study the dynamics of pure oleic acid and grafted oleic acid synthesized by decomposing iron oleate into oleic acid grafted iron oxide nanoparticles. Our quasielastic neutron scattering study shows that oleic acid dominantly performs translational diffusion at room temperature. On the other hand, in nanocomposites, constraints imposed by grafting and crowding of neighboring chains restrict the grafted oleic acid to uniaxial rotation. Interestingly, it also manifests mobility in grafted oleic acid below the crystallization temperature of pure oleic acid. The data from grafted oleic acid could be effectively described using a uniaxial rotational diffusion model with an additional elastic scattering contribution. This kind of elastic scattering arises due to the restricted bond mobility and increases with decreasing temperature. The radius of rotation obtained from the fitted data agrees very well with the geometry of the molecule and grafting density. These results open possibilities of research on the confined surfactant systems, which could be analyzed using the approach described here.
A novel compressible enstrophy transport equation-based analysis of instability during Magnus–Robins effects for high rotation rates
Authors: Suman Vajjala K. , Sundaram Prasannabalaji , Puttam J. K. , Sengupta Aditi , Sengupta Tapan K.
Published: April 2022

The effects of compressibility on the instability of a two-dimensional flow past a rotating cylinder executing high rotation rates are investigated, in detail, using a novel analysis based on the compressible enstrophy transport equation (CETE). Accurate analysis of the instability necessitates the generation of high fidelity numerical solutions, and this is achieved by employing optimized numerical methods that enable high accuracy direct numerical simulation of compressible flows. To study the effects of compressibility induced by rotation alone, a low free stream Mach number and two high rotation rates are considered, as compared to that reported in the literature. Results demonstrate single-sided vortex shedding, the presence of significant compressibility in the flow field confirmed by local Mach number, and temperature and density gradient fields with transient formation of supersonic pockets noted for the higher rotation speed cases. The temporal instability is studied by analyzing the relative contributions of different terms in the CETE to the growth of enstrophy. As per the authors' knowledge, this is the first such research effort demonstrating an application of the CETE for instabilities. Analysis shows that viscous diffusion is the dominant mechanism in creating the flow instability with a secondary role played by the baroclinic mechanism.
Book Review
Authors: Stadtländer Christian T. K.-H.
Published: April 2022

The article emphasises the value of marine protected areas (MPAs) and the efforts made by conservationists to protect animal biodiversity in pelagic environments. The article is based on and includes data described in the book ‘Conserving the Oceans: The Politics of Large Marine Protected Areas’ by Justin Alger. It is about the deconstruction of industry influence and stakeholder behaviour during the establishment of three large-scale MPAs.
STING mediates neurodegeneration and neuroinflammation in nigrostriatal α-synucleinopathy
Authors: Hinkle Jared T. , Patel Jaimin , Panicker Nikhil , Karuppagounder Senthilkumar S. , Biswas Devanik , Belingon Bonn , Chen Rong , Brahmachari Saurav , Pletnikova Olga , Troncoso Juan C. , Dawson Valina L. , Dawson Ted M.
Published: April 2022

Significance

It is increasingly recognized that chronic neuroinflammation is causally relevant to neurodegeneration. In Parkinson’s disease (PD), α-synuclein pathology activates inflammatory signaling that disturbs parenchymal homeostasis and disrupts neuron-glia interactions. Herein, we report that the innate immune cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) DNA-sensing pathway is activated in a mouse model of α-synucleinopathy and parkinsonism, leading to type-I interferon activation that precedes the onset of neurodegeneration. Remarkably, STING-deficient mice were protected from dopaminergic neuron loss in this model. We also show that αSyn aggregates can increase STING expression and augment canonical STING activation, suggesting a possible generalized propensity for exaggerated antiviral responses in neurological states with STING elevation. Our results suggest that STING inhibition may be therapeutic in idiopathic PD and possibly other human α-synucleinopathies.
In situ optical spectroscopy of crystallization: One crystal nucleation at a time
Authors: Urquidi Oscar , Brazard Johanna , LeMessurier Natalie , Simine Lena , Adachi Takuji B. M.
Published: April 2022

Significance

It is of fundamental importance to establish the microscopic picture of crystal nucleation for both academic and industrial research. Here, we report an in situ time-resolved Raman spectroscopy to study crystallization from solution, one crystal nucleation at a time. The observed dynamics of α-glycine crystallization from water without any additive supports the nonclassical nucleation pathway, where prenucleation aggregates form and convert to a crystal. By the direct comparison of Raman spectrum of the aggregates between the experiment and simulation, we propose the structure of these aggregates as linear hydrogen-bonded networks. We demonstrate the power of studying one nucleation event at a time, which can accelerate the investigation of crystal nucleation by optical spectroscopy.
Negative ion density in the ion source SPIDER in Cs free conditions
Authors: Barbisan M , Agnello R , Casati G , Pasqualotto R , Poggi C , Sartori E , Spolaore M , Serianni G
Published: April 2022

The SPIDER experiment, operated at the Neutral Beam Test Facility of Consorzio RFX, Padua, hosts the prototype of the H−/D−ion source for the ITER neutral beam injectors. The maximization of the ion current extracted from the source and the minimization of the amount of co-extracted electrons are among the most relevant targets to accomplish. The Cavity Ring-Down Spectroscopy diagnostic measures the negative ion density in the source close to the plasma grid (the plasma-facing grid of the ion acceleration system), so to identify the source operational parameters that maximize the amount of negative ions which can be extracted. In this study SPIDER was operated in hydrogen and deuterium in Cs-free conditions, therefore negative ions were mostly produced by reactions in the plasma volume. This work shows how the magnetic filter field and the bias currents, present in SPIDER to limit the amount of co-extracted electrons, affect the density of negative ions available for extraction. The results indicate that the magnetic filter field in front of the acceleration system should be set between about 1.6 mT, condition that maximizes the density of available negative ions, and about 3.2 mT, condition that minimizes the ratio of electron current to ion current. The negative ion density also resulted to be maximized when the plasma grid and its surrounding bias plate was positively biased against the source body with a total current in the range 0–100 A. The paper shows also how much, in Cs-free conditions, the electric fields in the acceleration system can affect the density of negative ions in the source, close to the plasma grid apertures.
Leakage current suppression and breakdown voltage enhancement in GaN-on-GaN vertical Schottky barrier diodes enabled by oxidized platinum as Schottky contact metal
Authors: Shi Zhongyu , Xiang Xueqiang , Zhang Haochen , He Qiming , Jian Guangzhong , Zhou Kai , Zhou Xuanze , Xing Chong , Xu Guangwei , Long Shibing
Published: April 2022

In this work, the oxidized metal PtO
x
was employed as the Schottky contact metal in the fabrication of gallium nitride (GaN)-on-GaN vertical Schottky barrier diodes (SBDs). Compared with the GaN SBD with just Pt Schottky anode, the Pt/PtO
x
/Pt-GaN SBDs exhibited a substantial reduction in reverse leakage current density

J

R

from 5.2 × 10−6 A cm−2 to 5.6 × 10−9 A cm−2 (@ −50 V) and a large rise in the breakdown voltage (

V

BD

) from 152 to 368 V, as well as maintaining the similar on-state characteristics in terms of turn-on voltage and on resistance. The temperature-dependent current–voltage characteristics of the fabricated devices further revealed that the Pt/PtO
x
/Pt-GaN SBDs possessed a higher Schottky barrier height and better high-temperature stability. Such an improvement should be attributed to the electric dipole effect in the PtO
x
layer. Moreover, the additional thin Pt layer between PtO
x
and GaN almost have no influence on the electric dipole effect of PtO
x
but can effectively protect the GaN surface from plasma damage and oxidation during the PtO
x
deposition. We believe that the proposed Pt/PtO
x
/Pt-GaN Schottky contact scheme provides a straightforward and effective strategy to develop next-generation GaN power electronic devices.
Investigation of radiation shielding by adding Al2O3 and SiO2 into the high-speed steel composites: comparative study
Authors: Gökmen Uğur , Özkan Zübeyde , Taşcı Ufuk , Bilge Ocak Sema
Published: April 2022

In this study, Phy-X/PSD software was utilized for searching the neutron shielding and gamma-ray shielding features of the high-speed steel composites. The effects of the Al2O3 and SiO2 contents on the irradiation properties of the T15 (0.4Si, 0.4Mn, 0.5Mo, 1.5C, 4.5Cr, 4.75Co, 5.0 V, 12.5 W) + (0%–30%) composite material were examined. The properties of the linear attenuation coefficients (LAC), half-value layer (HVL), fast neutron removal cross-sections (FNRC), mean free path (MFP), effective conductivity (C

eff
), mass attenuation coefficient (MAC), exposure buildup factors (EBF), tenth-value layer (TVL), effective atomic number (Z

eff
) were determined for the energy varying between 0.015 MeV and 15 MeV. The investigation revealed that the MAC and LAC values in the T15 composite material declined with the increase in the SiO2 or Al2O3 contents in the composite. On the other hand, the Geometric Progression (G-P) method was utilized to determine the EBFs under the penetration depth of up to 40 mfp and the same energy range. According to the results of the G-P method, the values of HVL varied from 0.01 to0.034 cm, TVL values varied from 0.01 to 0.112 cm, while FNRC values varied from 6.584 cm−1 to 8.27 cm−1, and C

eff
values varied from 1.36 × 1011 S m−1 to 3.12 × 1011 S m−1. The results revealed that the T15 high-speed steel composite provided the maximum photon shielding capacity because it showed the lowest HVL value while showing the highest Z

eff
, and MAC values. The T15 + 20% Al2O3 composite material had the highest FNRC due to its higher density. The present investigation can be considered original in terms of a few aspects. Consequently, these new shielding materials can be chosen as shielding materials against gamma radiation. In addition to contributing to several popular technologies including space technologies and nanotechnology, the present study can also contribute to nuclear technology.
A novel solar radio spectrogram encryption algorithm based on parameter variable chaotic systems and DNA dynamic encoding
Authors: Shen Yupeng , Zou Tao , Zhang Lei , Wu Zhao , Su Yanrui , Yan Fabao
Published: April 2022

Considering that chaotic systems are highly sensitive to parameters, we design two new parameter variable chaotic systems by constructing parameter perturbation items. These systems are constructed using the state variables of the Liu chaotic system to perturb the parameters of the Lorenz and Chen chaotic systems and are called the Lorenz-Liu chaotic system (LLCS) and Chen-Liu chaotic system (CLCS), respectively. In particular, the parameter perturbation items constructed in this study are not periodic but rather chaotic signals and change in real time. Compared with the original systems, they exhibit more complex randomness and dynamic behaviors. In the proposed cryptosystem, which considers the concept of Deoxyribonucleic Acid (DNA), the solar radio spectrogram is dynamically encoded through the LLCS, and then, the CLCS is used to scramble and diffuse the decoding matrices. In addition, the algorithm uses the 256-bit Secure Hash Algorithm (SHA-256) to generate the initial keys, which enhances the algorithm’s sensitivity to plaintext. Simulation results and security analysis show that the cryptosystem has a large key space and high key sensitivity, and can resist various attacks, such as differential attacks and chosen-plaintext attacks.
Fisher matrix for multiple tracers: the information in the cross-spectra
Authors: Abramo L. Raul , Ferri João Vitor Dinarte , Tashiro Ian Lucas
Published: April 2022

We derive general expressions for the multi-tracer Fisher matrix, both assuming that the cross-spectra are constrained by the auto-spectra, and also allowing for independent degrees of freedom in the cross-spectra.
We show that, just like the ratios of power spectra, the independent degrees of freedom of the cross-spectra are also not constrained by cosmic variance. Moreover, whereas the uncertainties in the ratios of power spectra decrease with the number density of the tracers as ∼ 1/√n̅, the uncertainties in the independent degrees of freedom of the cross-spectra decrease even faster, as ∼ 1/n̅. We also derive simple expressions for the optimal number of tracers in a survey.
Superfluid to Mott-insulator transition in a one-dimensional optical lattice
Authors: Liu Wenliang , Zheng Ningxuan , Jian Jun , Tian Li , Wu Jizhou , Li Yuqing , Fu Yongming , Li Peng , Sovkov Vladimir , Ma Jie , Xiao Liantuan , Jia Suotang
Published: April 2022

Bose–Einstein condensates (BEC) of sodium atoms are transferred into one-dimensional (1D) optical lattice potentials, formed by two laser beams with a wavelength of 1064 nm, in a shallow optical trap. The phase coherence of the condensate in the lattice potential is studied by changing the lattice depth. A qualitative change in behavior of the BEC is observed at a lattice depth of ∼ 13.7 E
r, where the quantum gas undergoes a transition from a superfluid state to a state that lacks well-to-well phase coherence.
Design of broadband achromatic metasurface device based on phase-change material Ge2Sb2Te5
Authors: Lv Shuyuan , Li Xinhui , Luo Wenfeng , Jia Jie
Published: April 2022

Based on the phase-change material Ge2Sb2Te5 (GST), achromatic metasurface optical device in the longer-infrared wavelength is designed. With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST, the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5 μm to 13 μm are realized. The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband. The simulation calculation results show that the full-width at half-maximum (FWHM) of the focusing spot reaches the diffraction limit at each wavelength. In addition, the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19°. The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces, but also provides new possibilities for the integration of optical imaging, optical coding and other related optical systems.
Spin freezing in the van der Waals material Mn2Ga2S5
Authors: Shen Jie , Xu Xitong , He Miao , Liu Yonglai , Han Yuyan , Qu Zhe
Published: April 2022

Geometrical frustration in low-dimensional magnetic systems has been an intriguing research aspect, where the suppression of conventional magnetic order may lead to exotic ground states such as spin glass or spin liquid. In this work we report the synthesis and magnetism study of the monocrystalline Mn2Ga2S5, featuring both the van der Waals structure and a bilayered triangular Mn lattice. Magnetic susceptibility reveals a significant antiferromagnetic interaction with a Curie–Weiss temperature θ
w ∼ –260 K and a high spin S = 5/2 Mn2+ state. However, no long range magnetic order has been found down to 2 K, and a spin freezing transition is found to occur at around 12 K well below its θ
w. This yields a frustration index of f = –θ
w/T
f ≈ 22, an indication that the system is highly frustrated. The absence of a double-peak structure in magnetic specific heat compared with the TM
2S4 compounds implies that the spin freezing behavior in Mn2Ga2S5 is a result of the competition between exchange interactions and the 2D crystalline structure. Our results suggest that the layered Mn2Ga2S5 would be an excellent candidate for investigating the physics of 2D magnetism and spin disordered state.
Theoretical study of M
6
X
2 and M
6
XX′ structure (M = Au, Ag; X,X′ = S, Se): Electronic and optical properties, ability of photocatalytic water splitting, and tunable properties under biaxial strain
Authors: Li Jiaqi , Cheng Xinlu , Zhang Hong
Published: April 2022

MoS2, a transition metal dichalcogenide (TMDC), has attracted significant amount of attention due to its direct bandgap, tunability and optical properties. Recently, a novel structure consisting of MoS2 and noble metal nanoclusters has been reported. Inspired by this, first principle calculations are implemented to predict the structures of M
6
X
2 and M
6
XX′ (M = Au, Ag; X, X′ = S, Se). The calculated bandgap, band edge position, and optical absorption of these structures prove that the silver compounds (Ag6
X
2 and Ag6
XX′) have great potential for catalytic water splitting. In addition, biaxial strain (tensile strain and compressive strain) is applied to adjust the properties of these materials. The bandgap presents a quasi-linear trend with the increase of the applied strain. Moreover, the transition between the direct and indirect bandgap is found. The outstanding electronic and optical properties of these materials provide strong evidence for their application in microelectronic devices, photoelectric devices, and photocatalytic materials.
Mobility edges generated by the non-Hermitian flatband lattice
Authors: Liu Tong , Cheng Shujie
Published: April 2022

We study the cross-stitch flatband lattice subject to the quasiperiodic complex potential exp(ix). We firstly identify the exact expression of quadratic mobility edges through analytical calculation, then verify the theoretical predictions by numerically calculating the inverse participation ratio. Further more, we study the relationship between the real–complex spectrum transition and the localization–delocalization transition, and demonstrate that mobility edges in this non-Hermitian model not only separate localized from extended states but also indicate the coexistence of complex and real spectrum.
Gravitational perturbations of the Einstein-Euler-Heisenberg black hole *
Authors: Luo Zhi , Li Jin
Published: April 2022

The prospect of using gravitational wave detections via the quasinormal modes (QNMs) to test modified gravity theories is exciting area of current research. Gravitational waves (GWs) emitted by a perturbed black hole (BH) will decay as a superposition of their QNMs of oscillations at the ringdown phase. In this work, we investigate the QNMs of the Einstein-Euler-Heisenberg (EEH) BH for both axial and polar gravitational perturbations. We obtain master equations with the tetrad formalism, and the quasinormal frequencies of the EEH BH are calculated in the 6th order Wentzel-Kramers-Brillöuin approximation. It is interesting to note that the QNMs of the EEH BH would differ from those of the Reissner-Nordström BH under the EH parameter, which indicates the EH parameter would affect the gravitational perturbations for the EEH BH.