bluuebunny/crossref_metadata_2025 huggingface dataset:
Sistematização das etapas para impressão de modelos 3D de deformidades ortopédicas
Authors: Pontes Mariana Demétrio de Sousa , Ramos Carlos Henrique , Cunha Luiz Antonio Munhoz da
Published: June 2022

Assim como em diversas áreas do conhecimento, a tecnologia de prototipagem rápida ou manufatura aditiva, conhecida popularmente como impressão tridimensional (3D), vem ganhando espaço na medicina nos últimos anos, com diferentes aplicações. Inúmeros são os benefícios desta ciência na cirurgia ortopédica, ao permitir a conversão de exames de imagem em modelos tridimensionais. Diante disso, o objetivo do presente estudo é descrever um passo-a-passo prático para a impressão de peças a partir de exames de imagem de pacientes. Trata-se de um estudo metodológico, considerando exames de tomografia computadorizada (TC) pré-operatórios de pacientes portadores de deformidades ortopédicas. Inicialmente, o exame em formato digital imaging and communications in medicine (DICOM, na sigla em inglês) deve ser importado para o software de reconstrução tridimensional de estruturas anatômicas para o processo de segmentação e de conversão para o formato stereolithography (STL, na sigla em inglês). A próxima etapa é a importação do arquivo STL para o software de modelagem 3D, o qual permite trabalhar de forma livre manipulando a malha 3D. Finalizado o processo de edição, deve-se transferir o arquivo para o software fatiador para realizar as configurações de impressão e para salvar o arquivo em formato G-code para a materialização do objeto na impressora. Os modelos 3D foram impressos de forma aditiva, na impressora de tecnologia fused deposition modeling (FDM, na sigla em inglês) GTMax3D Core A3v2.
Expression of Neuron-Specific Enolase and Other Neuroendocrine Markers is Correlated with Prognosis and Response to Therapy in Non-Hodgkin Lymphoma
Authors: Chowdhury Somshankar , Kataria S.P , Yadav Amit Kumar
Published: June 2022

Objective Non-Hodgkin lymphoma (NHL) is a common hematological malignancy. There is very little known about the expression of neuroendocrine immunohistochemical markers and their clinical significance in NHL due to the paucity of studies. Our objective was to study the expression of neuroendocrine immunohistochemical markers in NHL and correlate with clinical parameters.

Materials and Methods All cases diagnosed as NHL on morphology and immunohistochemistry (World Health Organization, 2016 classification) were included in the study. Immunohistochemistry for neuron-specific enolase (NSE), synaptophysin, and chromogranin A was performed. The results were correlated with clinical parameters and response to chemotherapy.

Results A total of 66 cases were included in the study with a male-to-female ratio of 3.1:1. The most frequent subtypes observed were diffuse large B-cell lymphoma not otherwise specified and follicular lymphoma. Among the neuroendocrine markers, positivity was observed only for NSE, whereas the other markers were uniformly negative. It was positive in both B- and T-cell lymphomas and in many different subtypes. No relation with the age and sex of the patients was observed. However, NSE-positive cases, more frequently, presented in the advanced stage as compared with NSE negative (61 vs. 38%). All NSE-positive cases showed remission with chemotherapy.

Conclusion Among the neuroendocrine immunohistochemical markers, positivity was observed only for NSE. This isolated positivity suggests cross-binding of NSE antibodies with some other isoenzyme of NSE. NSE positivity was associated with higher stage and better response to therapy. Despite this apparent paradox, it is recommended that NSE should be part of routine immunohistochemical panel for NHL.
An Australian Algorithm to Guide the Surgical Management of Chronic Prosthetic Joint Infection: A Multi-Disciplinary Team Approach
Authors: Jiang Melinda , Sires James , Daniel Santhosh , Roberts Matthew B. , Wilson Christopher
Published: June 2022

Chronic prosthetic joint infection (PJI) is a leading cause of failure for total joint arthroplasty. Historically, two-stage revision arthroplasty has been considered the gold standard approach to chronic PJI, however, emerging evidence suggests that one-stage revision arthroplasty may be underutilized. To our knowledge, there have been no previously published guidelines for the surgical management of chronic PJI in Australia, resulting in significant heterogeneity in management within and across centers. We aim to review contemporary concepts in the surgical management of PJI and develop an evidence-based algorithm to optimize the management of chronic hip and knee PJI, incorporating a multidisciplinary team (MDT) approach. A review was conducted to identify existing articles discussing surgical management of chronic PJI, specifically contraindications to one-stage revision arthroplasty. Absolute contraindications for one-stage revision include difficulty in treating organisms, significant soft tissue compromise, and concurrent sepsis. Relative contraindications include lack of preoperative identification of organism, presence of a sinus tract, fungal infections, significant bone loss, and immunocompromise. In determining the management of patients with a relative contraindication, MDT discussion with the consideration of patient's overall local, host, and microbiological profile is necessary. Using gathered evidence, absolute and relative contraindications for one-stage revision arthroplasty were developed into an algorithm. The algorithm is designed to assist our PJI MDT in making optimized decisions when choosing between a one-stage versus two-stage approach. Ongoing follow-up is underway to determine the effect of implementing this algorithm on patient outcomes, eradication rates, and revision rates within our center.
Bounded weak and strong time periodic solutions to a three-dimensional chemotaxis-Stokes model with porous medium diffusion
Authors: Ye Hailong , Jin Chunhua
Published: June 2022

In this paper, we study the time periodic problem to a three-dimensional chemotaxis-Stokes model with porous medium diffusion Δnm and inhomogeneous mixed boundary conditions. By using a double-level approximation method and some iterative techniques, we obtain the existence and time-space uniform boundedness of weak time periodic solutions for any m > 1. Moreover, we improve the regularity for m≤43 and show that the obtained periodic solutions are, in fact, strong periodic solutions.
Thermal stability of antiferroelectric-like Al:HfO2 thin films with TiN or Pt electrodes
Authors: Payne Alexis , Alex Hsain H. , Lee Younghwan , Strnad Nicholas A. , Jones Jacob L. , Hanrahan Brendan
Published: June 2022

HfO2-based antiferroelectric-like thin films are increasingly being considered for commercial devices. However, even with initial promise, the temperature sensitivity of electrical properties such as loss tangent and leakage current remains unreported. 50 nm thick, 4 at. % Al-doped HfO2 thin films were synthesized via atomic layer deposition with both top and bottom electrodes being TiN or Pt. A study of their capacitance vs temperature showed that the Pt/Al:HfO2/Pt had a relative dielectric permittivity of 23.30 ± 0.06 at room temperature with a temperature coefficient of capacitance (TCC) of 78 ± 86 ppm/°C, while the TiN/Al:HfO2/TiN had a relative dielectric permittivity of 32.28 ± 0.14 at room temperature with a TCC of 322 ± 41 ppm/°C. The capacitance of both devices varied less than 6% over 1 to 1000 kHz from −125 to 125 °C. Both capacitors maintained loss tangents under 0.03 and leakage current densities of 10−9–10−7 A/cm2 between −125 and 125 °C. The TiN/Al:HfO2/TiN capacitor maintained an energy storage density (ESD) of 18.17 ± 0.79 J/cm3 at an efficiency of 51.79% ± 2.75% over the −125 to 125 °C range. The Pt/Al:HfO2/Pt capacitor also maintained a stable ESD of 9.83 ± 0.26 J/cm3 with an efficiency of 62.87% ± 3.00% over the same temperature range. Such low losses in both capacitors along with their thermal stability make antiferroelectric-like, Al-doped HfO2 thin films a promising material for temperature-stable microelectronics.
Optimal control of the reaction–diffusion process on directed networks
Authors: Liu Chen , Gao Shupeng , Song Mingrui , Bai Yue , Chang Lili , Wang Zhen
Published: June 2022

Reaction–diffusion processes organized in networks have attracted much interest in recent years due to their applications across a wide range of disciplines. As one type of most studied solutions of reaction–diffusion systems, patterns broadly exist and are observed from nature to human society. So far, the theory of pattern formation has made significant advances, among which a novel class of instability, presented as wave patterns, has been found in directed networks. Such wave patterns have been proved fruitful but significantly affected by the underlying network topology, and even small topological perturbations can destroy the patterns. Therefore, methods that can eliminate the influence of network topology changes on wave patterns are needed but remain uncharted. Here, we propose an optimal control framework to steer the system generating target wave patterns regardless of the topological disturbances. Taking the Brusselator model, a widely investigated reaction–diffusion model, as an example, numerical experiments demonstrate our framework’s effectiveness and robustness. Moreover, our framework is generally applicable, with minor adjustments, to other systems that differential equations can depict.
Convolutional neural network based prediction of effective diffusivity from microscope images
Authors: Ranjan Sethi Smruti , Kumawat Vinit , Ganguly Somenath
Published: June 2022

This study presents a method to predict the effective diffusivity of porous media from a limited set of scanning electron microscope images using deep learning. The electrodeposited nickel oxide film over carbon nanostructure, meant to provide electrochemical capacitance based on diffusion of ions through the film's pore space, was observed under the scanning electron microscope. Gray scale SEM images were converted to binary images, and the effective diffusivity was found using lattice Boltzmann simulations. A convolutional neural network (CNN) model comprising two sets of convolution and pooling layers and a fully connected layer was trained with lattice Boltzmann method data, where the choices of kernel size and stride were made, keeping the homogeneity of the image in perspective. An initial attempt to train a CNN with 900 training instances predicted effective diffusivity with a relative error of 13.33%, 43.49%, and 36.41% for the training, validation, and test set, respectively. However, it was over-predicting the diffusivities for images with very low connectivity. Isolated pores within the images were identified and were eliminated to solve this issue before using the images to train another CNN. This second network worked well for images with low connectivity and brought down the mean relative error from 36.41% to 25.43% for the test set. The error was found to vary across the images due to highly non-even representation of different image types, increasing by complex pore connectivity at lower porosity for which the number of training instances is the least, and overfitting of networks on medium porosity images that are present in greater numbers. The SEM images were further classified based on porosity as well as pore connectivity. The training was performed with one category of images, and the testing was conducted with images of another category at the other end of the spectrum to evaluate CNN efficacy upon encountering a new category of images. The results show the ability of the network to extend the prediction to an unknown electrode morphology, which is critical for the analysis of SEM images.
Electron Weibel instability induced magnetic fields in optical-field ionized plasmas
Authors: Zhang Chaojie , Wu Yipeng , Sinclair Mitchell , Farrell Audrey , Marsh Kenneth A. , Hua Jianfei , Petrushina Irina , Vafaei-Najafabadi Navid , Kupfer Rotem , Kusche Karl , Fedurin Mikhail , Pogorelsky Igor , Polyanskiy Mikhail , Huang Chen-Kang , Lu Wei , Mori Warren B. , Joshi Chan
Published: June 2022

Generation and amplification of magnetic fields in plasmas is a long-standing topic that is of great interest to both plasma and space physics. The electron Weibel instability is a well-known mechanism responsible for self-generating magnetic fields in plasmas with temperature anisotropy and has been extensively investigated in both theory and simulations, yet experimental verification of this instability has been challenging. Recently, we demonstrated a new experimental platform that enables controlled initialization of highly nonthermal and/or anisotropic plasma electron velocity distributions via optical-field ionization. Using an external electron probe bunch from a linear accelerator, the onset, saturation, and decay of the self-generated magnetic fields due to electron Weibel instability were measured for the first time to our knowledge. In this paper, we will first present experimental results on time-resolved measurements of the Weibel magnetic fields in non-relativistic plasmas produced by Ti:Sapphire laser pulses (0.8 μm) and then discuss the feasibility of extending the study to a quasi-relativistic regime by using intense CO2 (e.g., 9.2 μm) lasers to produce much hotter plasmas.
Effects of carrier storage in an uncapped Ge–Si core–shell nanocrystal on simulated nano-electron beam induced current
Authors: El Hdiy Abdelillah
Published: June 2022

Carrier trapping process inside an uncapped and spherical Ge–Si core–shell nanocrystal on the surface of an n-doped Si substrate and its effects on electron beam induced current are studied using a three-dimensional Monte Carlo simulation. Charges are generated using an electron beam energy of 5 keV in the perpendicular configuration and collected by a nanoscale electrode which establishes a nanojunction with the Si sample. The surface recombination velocity is equal to zero. The Ge–Si core–shell is assumed to exhibit type II confinement of band edge alignment in which holes are trapped inside the core and electrons inside the shell. The collection and trapping probabilities of a created carrier, when it emerges at the sample surface, are controlled by its electric nature (hole or electron), by distances separating it from the core–shell nanocrystal and from the nanoelectrode. Carrier probabilities and collection are also controlled by opening angles allowing the emerged charge to “see” the core–shell nanocrystal and the nanoelectrode. Results show that the electron trapping is distance independent, and it does not affect the induced current, while the hole collection and trapping processes depend on each other up to a threshold distance of ∼200 nm. Beyond this distance, no modification is observed either in the induced current, suggesting that the nanocrystal can no longer be detected, or in the hole capture process, suggesting a no potential overlapping between the nanocrystal and the nanoelectrode.
Via-based miniaturized rasorber using graphene films
Authors: Chen Biao , Wu Bian , Zhao Yu-Tong , Su Tao , Fan Yi-Feng
Published: June 2022

In this work, we present a miniaturized wideband rasorber with good angular stability using via-based metal–graphene structure. The rasorber consists of a compact lossy layer, a frequency-selective surface layer, and an air spacer in the middle. The metal–graphene structure in the lossy layer achieves a tiny period due to multiple metal vias connected with meander lines and open stubs. The graphene resistive films printed on the surface by screen-printing technology realize omnidirectional planar resistors for broadband absorption. The 1-dB transmission band of the rasorber is from 7.27 to 8.01 GHz and the 10-dB reflection band is from 2.54 to 8.58 GHz. Due to its miniaturized unit cell, both the transmission and absorption performance is stable with a large-angle incident wave. The ultra-miniaturized rasorber is fabricated and measured, which demonstrates a wide bandwidth of 108.6% and a small period of 0.05λL with great angular stability, making it a good candidate for bi-station stealth radome applications.
Mapping electric fields in real nanodevices by operando electron holography
Authors: Brodovoi Maria , Gruel Kilian , Masseboeuf Aurélien , Chapuis Lucas , Hÿtch Martin , Lorut Frédéric , Gatel Christophe
Published: June 2022

Nanoelectronic devices play an essential role in many domains, and their development and improvement attract considerable attention in fundamental and applied research. Access to the local physical processes involved in these nanosystems during their operation is, therefore, crucial. We show how electric fields in real nanodevices can be studied under working conditions using operando electron holography. A specific sample preparation method was first developed to bias electron-transparent nanodevices extracted from production lines while ensuring their electrical connectivity and functionality without employing dedicated probe-based holders. Metal–insulator–metal nanocapacitors were prepared using this approach based on focused ion beam circuit modification. Operando electron holography allowed the electric potential to be quantitatively mapped in the active areas, and between devices, while biasing the devices in situ. Experimental results were compared with finite element method modeling simulations to determine local electrical parameters. We demonstrate that electrical properties, such as capacitance and surface charge density, can be measured at the nanoscale and have been preserved by our sample preparation methodology when compared to macroscopic measurements. This work paves the way for mapping the local electrical properties of more complex biased devices.
Impact response of pre-strained pure vanadium
Authors: Zaretsky E. B. , Frage N. , Kalabukhov S. , Savinykh A. S. , Garkushin G. V. , Razorenov S. V.
Published: June 2022

The effect of modest, 0.6% and 5.5%, pre-straining on the impact response of 2 mm thick samples of annealed polycrystalline vanadium of commercial purity was studied in a series of planar impact tests. The loading of the samples by 0.5 mm thick copper impactors having velocities varying between 300 and 610 m/s was accompanied by continuous laser Doppler velocimetry of their rear surface. Based on the recorded velocity histories, the dynamic compressive σY and tensile (spall) σsp strengths and the strength σYsc of vanadium in the shock-compressed state were determined. Adjacent to the impact surface part of the cross sections of the softly recovered samples, the number of twins Ntw per unit area was counted. It was found that the main parameter governing both the strength σY of pristine (in the shock sense) material and that in the shock-compressed state, σYsc, was the initial dislocation density η0. Moreover, the dislocation surplus caused by pre-straining was responsible for complete suppressing of twinning in the 0.6% and 5.5% pre-strained samples. In undeformed vanadium, the twinning was partially suppressed by the presence of impurity atoms which, however, did not affect the twinning stress, which was equal to approximately 0.7 GPa.
CO2 number density measurement in a shock tube with preheated carbon surface
Authors: Shim Hanseul , Lee Sanghoon , Kim Jae Gang , Park Gisu
Published: June 2022

The interaction between a heated carbon-based material and high-temperature air may produce ablation gas species such as CO2, affecting heat transfer onto the surface of a thermal protection system. The prediction of ablation gas production is critical for heat flux prediction and the design of a thermal protection system. In this study, we present a system that measures the number density of CO2 formed by the gas–surface interaction between a hot carbon surface and high-temperature gas. The heated carbon wall is exposed to high-temperature air by using a shock tube and surface heating model. The surface temperature of the carbon wall is measured using two-color ratio pyrometry. The number density of CO2 is predicted by performing numerical calculations for the shock tube flow with gas–surface interaction modeling. The number density of CO2 molecules is measured using infrared emission spectroscopy. The measured CO2 number density is 9.60 × 1023 m−3 at an area-weighted average surface temperature of 1212 K. The measured number density matches the predicted value within an error of 6%. The proposed system is applicable for CO2 number density measurement under various gas–surface interaction conditions, and it can be used for the investigation of ablative gas production and numerical research on gas–surface interactions.
Temperature and velocity characteristics of rotating turbulent boundary layers under non-isothermal conditions
Authors: Tao Zhi , You Ruquan , Ma Yao , Li Haiwang
Published: June 2022

This paper describes an experimental investigation, by means of hot-wire anemometry, of the characteristics of velocity and temperature in a rotating turbulent boundary layer under isothermal and non-isothermal conditions. The ranges of experimental parameters are as follows: Reynolds number from 10 000 to 25 000, rotational speed from 0 to 150 rpm, and y+ from 1.8 to 100. The relative temperature difference is held constant at 0.1. Detailed velocity and temperature distributions in the boundary layer are measured in the rotating state, and a new criterion for boundary layer segmentation under rotation is proposed. The applicability of boundary layer theory under the rotating state is extended. The influence of Coriolis force and buoyancy on the velocity and temperature distributions in the turbulent boundary layers are analyzed. Coriolis force is found to play an important role in the behavior of the boundary layer under rotation, as it shifts the velocity and temperature boundary layers. Under isothermal conditions, such effects can be classified according to the dominant force: viscous, Coriolis, or inertial. Under non-isothermal conditions, buoyancy occurs. The buoyancy induced by the Coriolis force suppresses the effect of the Coriolis force, and the suppression effect increases with temperature difference. The variation of turbulent Prandtl number Prt under rotation is also obtained.
Mean-field theory for the structure of strongly interacting active liquids
Authors: Tociu Laura , Rassolov Gregory , Fodor Étienne , Vaikuntanathan Suriyanarayanan
Published: June 2022

Active systems, which are driven out of equilibrium by local non-conservative forces, exhibit unique behaviors and structures with potential utility for the design of novel materials. An important and difficult challenge along the path toward this goal is to precisely predict how the structure of active systems is modified as their driving forces push them out of equilibrium. Here, we use tools from liquid-state theories to approach this challenge for a classic minimal active matter model. First, we construct a nonequilibrium mean-field framework that can predict the structure of systems of weakly interacting particles. Second, motivated by equilibrium solvation theories, we modify this theory to extend it with surprisingly high accuracy to systems of strongly interacting particles, distinguishing it from most existing similarly tractable approaches. Our results provide insight into spatial organization in strongly interacting out-of-equilibrium systems.
Wetting failure in the early stage of water drop impact on a smooth solid surface
Authors: Adachi Ryunosuke , Kobayashi Kazumichi , Fujii Hiroyuki , Sanada Toshiyuki , Watanabe Masao
Published: June 2022

A water drop impacting a dry solid surface can eject a thin liquid sheet, which is forced to expand on the surface to wet the solid surface. Wetting failure, which produces defects in applications based on the impact of drops, including coating, cooling, cleaning, and printing, may occur with a sufficiently large liquid-sheet velocity. However, the exact onset of wetting failure when a drop impacts the surface has yet to be determined. Therefore, we examine the dependence of rim instability immediately after liquid-sheet ejection on the static contact angle of the solid surface at the instant of water drop impact. This study is the first attempt to solve this problem and is made possible only by using an ultra-high-speed camera. We revealed that wetting failure can occur by investigating the rim instability of the liquid sheet.
Planar, longitudinal, compressive waves in solids: Thermodynamics and uniaxial strain restrictions
Authors: Burns S. J. , Rygg J. Ryan , Polsin Danae , Henderson Brian , Marshall Michelle , Zhang Shuai , Hu Suxing , Collins Gilbert
Published: June 2022

A new tri-axial pressure-based constitutive expression has been found using Cauchy's stress tensor. This stress state emphasizes pressure and shear stress. The description is a pressure plus an effective shear stress allowing for a constitutive law based on atomic solid-state phase changes in crystalline cells due to pressure plus shear-based dislocation motion commonly associated with plasticity. Pressure has a new role in the material's constitutive response as it is separated from plasticity. The thermo-mechanical system describes third-order Gibbs’ expressions without specific volume restrictions placed upon the material. Isothermally, the ratio of heat to shear work in elastic copper is shown to approach zero at a very low temperature and become larger than one as temperature approaches melting. Wave compression models investigated are elastic and plastic: in fully elastic materials, the planar wave is restricted by Poisson's effect although plastic shear changes this constraint. Plastic deformation, dominated by dissipative shear stresses in uniaxial strain, heats the material while excluding phase changes from hydrostatic pressures. The material properties per se across Hugoniot shocks are described with entropy concepts. Shock waves are exceedingly complex since the constitutive laws are linked at extreme temperatures, pressures, and shear stresses. Isothermal, isentropic, isochoric, and iso-shear conditions are used throughout with Jacobian algebra.
ZBP1 promotes inflammatory responses downstream of TLR3/TLR4 via timely delivery of RIPK1 to TRIF
Authors: Muendlein Hayley I. , Connolly Wilson M. , Magri Zoie , Jetton David , Smirnova Irina , Degterev Alexei , Balachandran Siddharth , Poltorak Alexander
Published: June 2022

Significance

While ZBP1 is well documented to drive cell death in response to viruses, its role in the context of Toll-like receptor (TLR)–mediated immune activation remains less defined. Here, we show that ZBP1 promotes inflammation in response to bacterial lipopolysaccharide (LPS) or double-stranded RNA (dsRNA). In a dose dependent manner, ZBP1 promotes the recruitment of RIPK1 to the TLR3/4 adaptor TRIF, activating downstream inflammatory signaling. ZBP1 plays a crucial role in TRIF-dependent responses
in vivo
, as

Zbp1
−/−

mice exhibited resistance to LPS-induced hypothermia and attenuated inflammatory responses to dsRNA. Our findings suggest that ZBP1 plays a synergistic role in the immune response by driving inflammation downstream of TLRs in response to bacterial and viral components.
Signatures of glial activity can be detected in the CSF proteome
Authors: Eninger Timo , Müller Stephan A. , Bacioglu Mehtap , Schweighauser Manuel , Lambert Marius , Maia Luis F. , Neher Jonas J. , Hornfeck Sarah M. , Obermüller Ulrike , Kleinberger Gernot , Haass Christian , Kahle Philipp J. , Staufenbiel Matthias , Ping Lingyan , Duong Duc M. , Levey Allan I. , Seyfried Nicholas T. , Lichtenthaler Stefan F. , Jucker Mathias , Kaeser Stephan A.
Published: June 2022

Significance

Single-cell transcriptomics has revealed specific glial activation states associated with the pathogenesis of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s disease (AD and PD). What is still needed are clinically relevant biomarkers for deciphering such glial states in AD and PD patients. To this end, we applied proteome analysis in cerebrospinal fluid (CSF) of mouse models of AD and PD pathology. This allowed us to identify a panel of glial CSF proteins that largely match the transcriptomic changes. The identified proteins can also be quantified in human CSF and show changes in AD patients, supporting their relevance as biomarker candidates to stage glial activation in patients with neurodegenerative diseases.
Epidemiology ofMycobacterium bovisinfection in free-ranging rhinoceros in Kruger National Park, South Africa
Authors: Dwyer Rebecca , Goosen Wynand , Buss Peter , Kedward Simon , Manamela Tebogo , Hausler Guy , Chileshe Josephine , Rossouw Leana , Fowler James H. , Miller Michele , Witte Carmel
Published: June 2022

Significance

African rhinoceros survival is threatened by poaching, habitat loss, and climate effects. The presence ofMycobacterium bovisin wild populations creates an additional potential threat to health and conservation programs. This study reports a large survey ofM. bovisinfection in free-ranging rhinoceros. Our findings confirm a widespread, high infection burden in the rhinoceros population of Kruger National Park, South Africa and identify risk factors for infection. These findings provide a foundation for understanding the spread of bovine tuberculosis in complex ecosystems. This study reflects the complexity of investigating a multihost pathogen in a previously naïve system. It provides an opportunity to increase awareness of the global impact that tuberculosis can have on animal populations, food security, and conservation.
Insights into bear evolution from a Pleistocene polar bear genome
Authors: Lan Tianying , Leppälä Kalle , Tomlin Crystal , Talbot Sandra L. , Sage George K. , Farley Sean D. , Shideler Richard T. , Bachmann Lutz , Wiig Øystein , Albert Victor A. , Salojärvi Jarkko , Mailund Thomas , Drautz-Moses Daniela I. , Schuster Stephan C. , Herrera-Estrella Luis , Lindqvist Charlotte
Published: June 2022

The polar bear (
Ursus maritimus
) has become a symbol of the threat to biodiversity from climate change. Understanding polar bear evolutionary history may provide insights into apex carnivore responses and prospects during periods of extreme environmental perturbations. In recent years, genomic studies have examined bear speciation and population history, including evidence for ancient admixture between polar bears and brown bears (
Ursus arctos
). Here, we extend our earlier studies of a 130,000- to 115,000-y-old polar bear from the Svalbard Archipelago using a 10× coverage genome sequence and 10 new genomes of polar and brown bears from contemporary zones of overlap in northern Alaska. We demonstrate a dramatic decline in effective population size for this ancient polar bear’s lineage, followed by a modest increase just before its demise. A slightly higher genetic diversity in the ancient polar bear suggests a severe genetic erosion over a prolonged bottleneck in modern polar bears. Statistical fitting of data to alternative admixture graph scenarios favors at least one ancient introgression event from brown bears into the ancestor of polar bears, possibly dating back over 150,000 y. Gene flow was likely bidirectional, but allelic transfer from brown into polar bear is the strongest detected signal, which contrasts with other published work. These findings may have implications for our understanding of climate change impacts: Polar bears, a specialist Arctic lineage, may not only have undergone severe genetic bottlenecks but also been the recipient of generalist, boreal genetic variants from brown bears during critical phases of Northern Hemisphere glacial oscillations.
Global protected areas seem insufficient to safeguard half of the world's mammals from human-induced extinction
Authors: Williams David R. , Rondinini Carlo , Tilman David
Published: June 2022

Significance

Protected areas are vital for conserving global biodiversity, but we lack information on the extent to which the current global protected area network is able to prevent local extinctions. Here we investigate this by assessing the potential size of individual populations of nearly 4,000 terrestrial mammals within protected areas. We find that many existing protected areas are too small or too poorly connected to provide robust and resilient protection for almost all mammal species that are threatened with extinction and for over 1,000 species that are not currently threatened. These results highlight that global biodiversity targets must reflect ecological realities by incorporating spatial structure and estimates of population viability, rather than relying simply on the total area of land protected.
The topology of general cosmological models*
Authors: Galloway Gregory J , Khuri Marcus A , Woolgar Eric
Published: June 2022

Is the Universe finite or infinite, and what shape does it have? These fundamental questions, of which relatively little is known, are typically studied within the context of the standard model of cosmology where the Universe is assumed to be homogeneous and isotropic. Here we address the above questions in highly general cosmological models, with the only assumption being that the average flow of matter is irrotational. Using techniques from differential geometry, specifically extensions of the Bonnet–Myers theorem, we derive a condition which implies a finite Universe and yields a bound for its diameter. Furthermore, under a weaker condition involving the interplay between curvature and diameter, together with the assumption that the Universe is finite (i.e. has closed spatial slices), we provide a concise list of possible topologies. Namely, the spatial sections then would be either the ring topologies S
1 × S
2,

S

1

×

~

S

2

,

S

1

×
R

P

2

,

R

P

3

#
R

P

3

, or covered by the sphere S
3 or torus T
3. In particular, under this condition the basic construction of connected sums would be ruled out (save for one), along with the plethora of topologies associated with negative curvature. These results are obtained from consequences of the geometrization of three-manifolds, by applying a generalization of the almost splitting theorem together with a curvature formula of Ehlers and Ellis.
Importance of the Hubbard U parameter to explore accurate electronic and optical behaviour of BiFeO3
Authors: Ghosal Supriya , Dutta Kajari , Chowdhury Suman , Jana Debnarayan
Published: June 2022

Based upon Hubbard U corrected density functional theory (DFT), the electronic and optical responses of multiferroic Bismuth ferrite (BiFeO3; BFO) have been critically explored. Treating BFO as a strongly correlated insulating system, a Hubbard U parameter is considered for accurate description of localised Fe-3d states. However, the U parameter for the Fe-3d state is not sufficient as 2p states of O atoms are greatly influenced by Fe-3d states. Similar U parameters for Fe-3d as well as O-2p states are considered. An effective U value around 4.3 eV not only solves the band gap mismatch of BFO from both a theoretical and experimental aspect, but also predicts the exact nature of the band gap. Moreover, within this framework, the optical responses of BFO are critically investigated. Multiple transitions appearing in both theoretical and experimental absorption spectra are well explained by crystal field transitions of Fe3+ ions in a d5 high spin state, supported by the density of states curve of BFO. Therefore, based upon the DFT + U approach, accurate electronic and optical characteristics of BFO are critically explored, which is essential for its multidirectional application perspectives.
Influence of Mg doping level at the initial growth stage on the gate reliability of p-GaN gate HEMTs
Authors: Guo Yijin , Wang Haodong , Chen Xin , Gao Hongwei , Li Fangqing , Zhong Yaozong , Zhou Yu , Li Qian , Li Wenbo , Sun Qian , Yang Hui
Published: June 2022

This letter has studied the gate reliability of p-GaN high electron mobility transistors (HEMTs) influenced by the Mg doping level at the initial growth stage of p-GaN layer. Normally-off HEMTs with p-GaN gate fabricated with relatively low and high Mg doping concentration have been analyzed and compared based on their performances at various statuses of as-fabricated, forward step-stressed, reverse step-stressed and long-term reverse stressed. It reveals that Mg over-doping has a detrimental effect on the p-GaN gate reliability through degrading the PIN diode formed by p-GaN/AlGaN/GaN structure. Severe drain current reduction, threshold voltage instability and gate leakage increase have been observed after being negatively stressed due to the high-density defects acting as apparent acceptor-like traps induced by Mg over-doping. The detailed studies on the p-GaN gate performance with various Mg concentrations give a greater depth of understanding to realize high gate reliability of p-GaN gate HEMTs.
A computational study of the double hysteresis phenomenon during reactive sputtering
Authors: Van Bever J , Strijckmans K , Depla D
Published: June 2022

When process parameters such as the reactive gas partial pressure or the discharge voltage are studied as a function of the reactive gas flow during reactive magnetron sputtering, the obtained curve has an S-shape. A direct consequence of this behaviour is that process control based on the reactive gas flow exhibits hysteresis. Under specific conditions, it is possible to observe two S-shaped curves: one when the reactive gas pressure is increased, the other during the return to the initial state by decreasing the reactive gas pressure. This behaviour has been described as double hysteresis behaviour. The origin of the double hysteresis behaviour is computationally studied by high-throughput calculations using a previously developed model. The influence of different process and material parameters were evaluated based on newly developed measures to characterize the calculated process curves. This high-throughput analysis reveals that the double hysteresis behaviour is linked to the difference in the removal rate of non-reacted implanted ions during the increase and decrease of the reactive gas pressure. Within the parameter space a region can be defined for which the double hysteresis behaviour is strong. The latter can not only assist further experiments to study this behaviour but also defines conditions to limit its impact. For Al, a discharge current density of approximately 0.025 A cm−2 was found to maximize double hysteresis.
Effects analogous to the Kekulé distortion induced by pseudospin polarization in graphene nanoribbons: confinement and coupling by breakdown of chiral correlation
Authors: Mendoza Michel , López Luis I A
Published: June 2022

We show here that potential barriers, applied to armchair nanoribbons, induce a hexagonal effective lattice, polarized in pseudospin on the sides of the barriers system, which has an effective unit cell greater than that of infinite graphene (pseudospin superstructure). This superstructure is better defined with the increase of the barrier potential, until a transport gap is generated. The superstructure, as well as the induced gap, are fingerprints of Kekulé distortion in graphene, so here we report an analogous effect in nanoribbons. These effects are associated with a breakdown of the chiral correlation. As a consequence, an effective zigzag edge is induced, which controls the electronic transport instead of the original armchair edge. With this, confinement effects (quasi-bound states) and couplings (splittings), both of chiral origin (decorrelation between chiral counterparts), are observed in the conductance as a function of the characteristics of the applied barriers and the number of barriers used. In general, the Dirac-like states in the nanoribbon can form quasi-bound states within potential barriers, which explains the Klein tunneling in armchair nanoribbons. On the other hand, for certain conditions of the barriers (width L and potential V) and the energy (E) of the quasi-particle, quasi-bound states between the barriers can be generated. These two types of confinement would be generating tunneling peaks, which are mixed in conductance. In this work we make a systematic study of conductance as a function of E, L and V for quantum dots systems in graphene nanoribbons, to determine fingerprints of chirality: line shapes and behaviors, associated with each of these two contributions. With these fingerprints of chirality we can detect tunneling through states within the barriers and differentiate these from tunneling through states formed between the barriers or quantum dot. With all this we propose a technique, from conductance, to determine the spatial region that the state occupies, associated with each tunneling peak.
Thermodynamics and phase stability of Li8
XO6 octalithium ceramic breeder materials (X = Pb, Ce, Ge, Zr, Sn)
Authors: Davies Andrew W , Murphy Samuel T
Published: June 2022

Octalithium ceramics with their high stoichiometric concentration of lithium offer exceptionally high tritium breeding ratios in comparison with other candidate breeder materials for tokamak fusion reactors, this is especially true with incorporation of a neutron multiplier into the crystal structures. Although, there are concerns surrounding the stability of these materials at operational temperatures. Therefore in this paper, we explore the thermodynamic properties of a selection of candidate octalithium ceramics in low and high temperature regimes (0–1200 K) using density functional perturbation theory. Enthalpies as well as Gibbs formation energies were used to distinguish candidates which may or may not be susceptible to degradation.
Heterogeneous Pd-PdO mesoporous film for ammonia electrosynthesis
Authors: Zhang Mei , Cui Lin , Mao Qiqi , Wang Ziqiang , Yu Hongjie , Xu You , Li Xiaonian , Wang Liang , Wang Hongjing
Published: June 2022

Exploring cost-effective and highly active electrocatalysts is of great significance for sustainable electrochemical NH3 synthesis. Palladium (Pd)-based catalysts have been unanimously considered as one of the most efficient catalysts for the nitrogen reduction reaction (NRR). Herein, self-supported mesoporous Pd film with partial oxidation on Ni foam (mPd-PdO/NF) was synthesized through the micelle-assisted chemical replacement method coupled with air oxidation under 260 °C, and the mPd-PdO/NF electrocatalyst exhibited superior NRR performance with the maximum values of r
NH3 (24.8 mg h−1 mgcat.
−1) and FE (16.64%) were obtained at −0.1 V, relative to the single counterparts (mPd/NF and mPdO/NF). It is proposed that both metallic Pd and its oxide domains when co-existing with a phase boundary between them can facilitate nitrogen activation and hydrogenation, resulting in an enhanced NRR performance. This work provides an inspiring strategy for the rational design of highly active and durable metal–metal–oxide nanoarchitectonics for ammonia electrosynthesis.
Effect of cubic and hexagonal boron nitride additions on the microstructure and properties of bulk MgB2 superconductors
Authors: Gao Zilin , Santra Sangeeta , Grovenor Chris R M , Speller Susannah C
Published: June 2022

MgB2 is a promising material for intermediate temperature applications where conventional low temperature superconductors cannot be used, especially if the range of magnetic fields over which is has acceptable current carrying performance can be expanded. However, its applicability is limited by poor properties at elevated magnetic fields. Carbon-based dopants can be used to dramatically improve the high-field performance of MgB2, but at the cost of a reduction in the superconducting transition temperature (T
c) that limits the operation temperature to 20 K or below. Here we report an enhancement of superconducting performance of MgB2 with the addition of cubic and hexagonal boron nitride (BN), without any significant reduction in T
c. Ex-situ bulk samples of MgB2 with two forms of BN addition were manufactured by the field assisted sintering technique after high energy ball milling of powder mixtures. We find that hexagonal BN (hBN) nanoparticles mixed homogenously with MgB2 powder react much more easily to produce Mg–N–B impurities than larger cubic BN (cBN) particles (∼10 µm) under the same processing conditions. The addition of 1 wt% hBN or 5 wt% cBN combined with 6 h of milling has been demonstrated to improve the critical current density (J
c) of MgB2 over the entire magnetic field range. It is proposed that the nano-sized Mg–N–B impurities, that typically reside at MgB2 grain boundaries, increase pinning strength by introducing additional flux pinning centres. In addition, excess Mg may benefit the low-field performance by improving the connectivity. This work shows the significance of microstructural characterization on inhomogeneous superconducting materials to analyse their performance.
Imaginary spin-orbital coupling in parity-time symmetric systems with momentum-dependent gain and loss
Authors: Qin Jieli , Zhou Lu , Dong Guangjiong
Published: June 2022

Spin-orbital coupling (SOC) and parity-time(PT)symmetry both have attracted paramount research interest in condensed matter physics, cold atom physics, optics and acoustics to develop spintronics, quantum computation, precise sensors and novel functionalities. Natural SOC is an intrinsic relativistic effect. However, there is an increasing interest in synthesized SOC nowadays. Here, we show that in aPT-symmetric pseudo spin-1/2 system (in other words, two-state system), the momentum-dependent balanced gain and loss can synthesize a new type of SOC, which we call imaginary SOC. The imaginary SOC can substantially change the energy spectrum of the system. Firstly, we show that it can generate a pure real energy spectrum with a double-valleys structure. Therefore, it has the ability to generate supersolid stripe states. Especially, the imaginary SOC stripe state can have a high contrast of one. Moreover, the imaginary SOC can also generate a spectrum with tunable complex energy band, in which the waves are either amplifying or decaying. Thus, the imaginary SOC would also find applications in the engineering ofPT-symmetry-based coherent wave amplifiers/absorbers. Potential experimental realizations of imaginary SOC are proposed in cold atomic gases and systems of coupled waveguides constituted of nonlocal gain and loss.
Constraining non-minimally coupled β-exponential inflation with CMB data
Authors: dos Santos F.B.M. , Santos da Costa S. , Silva R. , Benetti M. , Alcaniz J.S.
Published: June 2022

The β-exponential inflation is driven by a class of primordial potentials, derived in the framework of braneworld scenarios, that generalizes the well-known power law inflation. In this paper we update previous constraints on the minimal coupled β-exponential model [1] and extend the results also deriving the equations for the non-minimal coupled scenario. The predictions of both models are tested in light of the latest temperature and polarization maps of the Cosmic Microwave Background and clustering data. We also compare the predictions of these models with the standard ΛCDM cosmology using the Deviance Information Criterion (DIC), and find that the observational data show a moderate preference for the non-minimally coupled β-exponential inflationary model.
Carrier-envelope phase effect on light bullet dynamics
Authors: Zaloznaya Elizaveta , Kompanets Victor , Savvin Alexander , Dormidonov Alexander , Chekalin Sergey , Kandidov Valery
Published: June 2022

A light bullet (LB) is a wave packet of a few optical cycles that is extremely compressed in space and time, which is formed in the bulk transparent dielectric during femtosecond filamentation under anomalous group velocity dispersion. We demonstrate for the first time that the carrier-envelope phase shift during propagation of a near single-cycle LB causes synchronous oscillations of the spatial, temporal and energy parameters of its core with the period decreasing with increasing carrier wavelength. When analyzing the structure of color centers and induced plasma channels in fluorides, it was experimentally found that LB parameter oscillations lead to a periodic change in the nonlinear optical interaction with the dielectric.