bluuebunny/crossref_metadata_2025 huggingface dataset:
Weather conditions, distribution of resources feed and dynamics of the spatial structure of the Great Cormorant in the water area of Lake Baikal
Authors: Mel’nikov Yuriy , Kupchinskiy Alexander , Nikolaev Yakov
Published: December 2023

On the basis of long-term observations (2018-2023), the features of the distribution of the Great Cormorant in the water area of Lake Baikal during the mass rise of young birds “on the wing” are considered, depending on the distribution of feed resources and the state of weather conditions. At this time, young birds do not yet have experience of independent food production and parents feed them for 10-15 days. In this regard, the availability and abundance of feed resources is very important for birds. Our observations revealed large, but temporary concentrations of birds in areas of high abundance of feed. Large concentrations of birds are also formed in places convenient for recreation during long periods of adverse weather conditions (from 3-4 to 6-7 days) – strong winds. Such clusters can reach several thousand and even several tens of thousands of birds. They form quickly and also disappear quickly as more favorable conditions are restored on other parts of this lake. This feature of the behavior of birds must be taken into account when carrying out accounting work on large areas, which include snd the water area of Lake Baikal. Accounting of birds from a launch along the coastline, with a detailed survey of colonies in places of their concentration, is the only acceptable method of monitoring the state of the population of the Great Cormorant on Lake Baikal.
Remote Sensing Monitoring on the Territory of the Volga Carbon Polygon (Republic of Tatarstan, Russia)
Authors: Usmanov Bulat , Gafurov Artur , Khomyakov Petr , Ivanov Maxim , Kozhevnikova Maria
Published: December 2023

Remote sensing technology and geographic information systems allow the assessment of terrestrial carbon stocks in large areas. The article considers the procedure of remote monitoring organization in the forest and water parts of the Volga Carbon polygon (Republic of Tatarstan, Russia). The main purpose of the article is to present the structure of remote monitoring of the polygon, show the results of the first year of remote research, and discuss the need to use other remote sensing methods. This study reviews and highlights the advantages and limitations of various remote sensing methods and sensors, including optical, multispectral, radar, and lidar, which are widely used for above-ground biomass (AGB) and carbon stocks (CS) estimation. The first results of field studies by unmanned aerial vehicle (UAV) at the Volga Carbon polygon are presented: orthophotomaps, digital terrain and relief models, bathymetric map and multispectral image time-series. Different remote sensing methods from echolocation to the multispectral survey are used, and the most optimal remote sensing data and processing methods are determined. For the first time for the Republic of Tatarstan, an integrated carbon balance monitoring system has been developed.
Inventory of lands of gardening partnerships with the purpose of increasing the efficiency of territory use
Authors: Kotlyarova E. , Melentiev A. , Chursin A. , Nartova E.
Published: December 2023

The purpose of the paper is to study and analyze the inventory of lands of gardening partnerships as a way to increase the efficiency of use of the territory using the example of gardening partnerships in the Belomestnensky rural settlement of the Belgorod region. As a result of the survey, it was revealed that out of 17 SNT, in 7 the actual area is larger than the area allocated by decisions and regulations of the authorities, in 6 the situation is the opposite: the actual area is less. For a clear example, potential revenues from paying land taxes to the local budget were calculated and analyzed before and after inclusion within the boundaries of a populated area and the transfer of land from “gardening” to “individual housing construction.” As a result of studying the scientific material and the regulatory framework, the conclusion was made: an inventory of lands of gardening partnerships is an effective tool for increasing the efficiency of use of the territory of a municipality.
Optimizing network robustness via Krylov subspaces
Authors: Massei Stefano , Tudisco Francesco
Published: December 2023

We consider the problem of attaining either the maximal increase or reduction of the robustness of a complex network by means of a bounded modification of a subset of the edge weights. We propose two novel strategies combining Krylov subspace approximations with a greedy scheme and an interior point method employing either the Hessian or its approximation computed via the limited-memory Broyden-Fletcher-Goldfarb-Shanno algorithm (L-BFGS). The paper discusses the computational and modeling aspects of our methodology and illustrates the various optimization problems on networks that can be addressed within the proposed framework. Finally, in the numerical experiments we compare the performances of our algorithms with state-of-the-art techniques on synthetic and real-world networks.
Eine hundertprozentige Sicherheit gibt es nicht
Authors: Nienaber André , Breinbauer Irmi
Published: December 2023

Das Thema Sicherheit spielt in der akutpsychiatrischen Versorgung eine zentrale Rolle. So gehört die Schaffung einer sicheren Umgebung für Patienten in akuten psychiatrischen Ausnahmesituationen zu den zentralen Aufgaben einer psychiatrischen Akutstation. Doch was bedeutet Sicherheit in diesem Zusammenhang genau? Der Artikel beschäftigt sich mit dem Begriff der Sicherheit und diskutiert Möglichkeiten zur Verbesserung von Sicherheit in multiprofessionellen Teams in der stationären akutpsychiatrischen Versorgung aus einer pflegefachlichen bzw. pflegewissenschaftlichen Perspektive.
Die Mitochondriopathie Diabetes mellitus – Intervention mit
(Mikro-)Nährstoffen: Update 2023
Authors: Gröber Uwe , Friedrichsen Hans-Peter
Published: December 2023

Bei diabetischer Stoffwechsellage kommt es in den Mitochondrien zur massiven
Bildung von Superoxidradikalen, wodurch diabetesspezifische Signalwege aktiviert
werden. Oxidativer und nitrosativer Stress mit Inflammation verknüpfen
bei genetischer Prädisposition und ungünstigem Lebensstil den
Typ-2-Diabetes mit schwerwiegenden Folgeerkrankungen wie Angio- und
Neuropathien. Neben einer frühzeitigen Diagnostik und optimalen
Stoffwechseleinstellung sollte bei Diabetes mellitus rechtzeitig durch
Interventionen in die pathologischen Prozesse der Angio- und Neuropathien
eingegriffen werden. Eine vielversprechende komplementär- und
präventivmedizinische Therapieoption ist die gezielte
frühzeitige Supplementierung mitochondrienprotektiver, antioxidativer
und den Kohlenhydratstoffwechsel-regulierender (Mikro-)Nährstoffe wie
Vitamin C, Coenzym Q10, B-Vitamine, Vitamin D, Vitamin K und Magnesium.
Safety or security?
Authors: Mahler Lieselotte , Oster Anna
Published: December 2023

Was bedeutet Sicherheit in der Akutpsychiatrie? Für wen ist was sicher? Wo können wir ansetzen, um mit Unsicherheiten sicher arbeiten zu können? Sicherheit ist ein komplexes Konstrukt. In der Diskussion um Sicherheit in der Akutpsychiatrie müssen verschiedene Dimensionen und Perspektiven der Sicherheit beachtet werden. Basierend auf praktischen Erfahrungen und wissenschaftlicher Evidenz werden Ansatzpunkte innerhalb und außerhalb der psychiatrischen Versorgungsstrukturen für eine sichere Psychiatrie diskutiert.
Stellungnahme zur Altersuntergrenze bei der ambulanten Durchführung von Adenotomien und Tonsillotomien
Authors: Deitmer T. , Beck C. E. , Becke-Jakob K. , Eich C. , Hackenberg S. , Hoffmann T. K. , Koitschev A. , Löhler J. , Röher K. , Sittel C. , Welkoborsky H. J. , Wienke A. , Badelt G.
Published: December 2023

Mit Beginn des Jahres 2023 haben sich in der Regelung für das ambulante Operieren in Deutschland erhebliche Änderungen ergeben, die in einem trilateralen Vertrag der Selbstverwaltung zwischen dem Spitzenverband der gesetzlichen Krankenversicherungen, der Deutschen Krankenhausgesellschaft und der Kassenärztlichen Bundesvereinigung niedergelegt wurden. Hier wurden unter anderem in einem Katalog Tatbestände angegeben, unter denen eine Operation nicht oder nur fraglich ambulant durchgeführt werden sollte. In diesem Katalog wurde zum Patientenalter ausgeführt: „Bis zur Vollendung des ersten Lebensjahres kann eine stationäre Durchführung einer Leistung begründet sein.“ Diese Formulierung für sich bedeutet, dass Kinder ab einem Jahr regelhaft ambulant zu operieren sind.

In den wissenschaftlichen Fachgesellschaften für HNO-Heilkunde, Kopf und Halschirurgie sowie für Anästhesiologie und Intensivmedizin regten sich Zweifel, ob diese Altersgrenze auch für Operationen im Rachen wie Adenotomie oder Tonsillotomie wissenschaftlich begründbar sei.

Es wurde eine Recherche in internationalen Leitlinien sowie in der internationalen Literatur durchgeführt und die dortigen Aussagen bewertet. Die Ergebnisse dieser Literaturrecherche wurden mit Vertretern der Arbeitsgemeinschaft Pädiatrische HNO-Heilkunde (AG PädHNO), der Deutschen Gesellschaft für HNO-Heilkunde, Kopf- und Hals-Chirurgie (DGHNO-KHC) und dem wissenschaftlichen Arbeitskreis Kinderanästhesie (WAKKA) der Deutschen Gesellschaft für Anästhesiologie und Intensivmedizin (DGAI) in Konferenzen beraten.

Diese Konsensfindung ergab, dass eine strikte Altersgrenze mit dem vollendeten ersten Lebensjahr für die ambulante Durchführung von Adenotomien und Tonsillotomien nicht sachgerecht ist. Zunächst ist überhaupt die Angabe einer strikten Altersgrenze fragwürdig, da unabhängig vom Alter etliche andere medizinische und soziale Faktoren Einfluss auf die verantwortungsvolle Durchführbarkeit ambulanter Operationen haben. Im Weiteren ist die Altersgrenze von einem Jahr mit Blick auf Literatur, Leitlinien und praktische Ausübung im internationalen Bereich nicht als sachgerecht anzusehen. Die Bewertung der Literatur und die Beachtung der Durchführung im internationalen Bereich lassen eine Altersgrenze eher in dem Bereich von 2–3 Jahren als sachgerecht erscheinen.

Diese Übersichtsarbeit gibt den verantwortlichen Ärzten vielerlei Erkenntnisse, Aspekte und Argumente an die Hand, um die Entscheidung zur ambulanten oder stationären Durchführung dieser Operationen sachgerecht und verantwortungsvoll treffen zu können.
Pd-Catalyzed Oxidative Functionalization of Alkenes, Arenes, and 1,3-Dienes Using Molecular Oxygen as the Terminal Oxidant
Authors: Obora Yasushi , Tabaru Kazuki
Published: December 2023

This Account presents palladium-complex-catalyzed oxidative couplings mainly developed by the author’s group, including oxidative amination and silylation of terminal alkenes, direct oxidative arylation of aromatic compounds, and oxidative difunctionalization of 1,3-dienes. The catalytic cycles in these representative reactions feature re-oxidation of the palladium species with molecular oxygen as the terminal oxidant. Varying the combination of palladium catalyst and re-oxidant enables the formation of a variety of bonds through dehydrogenative cross-coupling reactions.

1 Introduction

2 Oxidative Amination of Terminal Alkenes

3 Direct Oxidative Arylation of Aromatic Compounds

4 Oxidative Silylation of Terminal Alkenes

5 Oxidative Difunctionalization of 1,3-Dienes

6 Conclusions and Perspectives
Deep Learning-Based Retinal Layer Segmentation in Optical Coherence Tomography Scans of Patients with Inherited Retinal Diseases
Authors: Eckardt Franziska , Mittas Robin , Horlava Nastassya , Schiefelbein Johannes , Asani Ben , Michalakis Stylianos , Gerhardt Maximilian , Priglinger Claudia , Keeser Daniel , Koutsouleris Nikolaos , Priglinger Siegfried , Theis Fabian , Peng Tingying , Schworm Benedikt
Published: December 2023

Background In optical coherence tomography (OCT) scans of patients with inherited retinal diseases (IRDs), the measurement of the thickness of the outer nuclear layer (ONL) has been
well established as a surrogate marker for photoreceptor preservation. Current automatic segmentation tools fail in OCT segmentation in IRDs, and manual segmentation is time-consuming.

Methods and Material Patients with IRD and an available OCT scan were screened for the present study. Additionally, OCT scans of patients without retinal disease were included to
provide training data for artificial intelligence (AI). We trained a U-net-based model on healthy patients and applied a domain adaption technique to the IRD patientsʼ scans.

Results We established an AI-based image segmentation algorithm that reliably segments the ONL in OCT scans of IRD patients. In a test dataset, the dice score of the algorithm was
98.7%. Furthermore, we generated thickness maps of the full retinal thickness and the ONL layer for each patient.

Conclusion Accurate segmentation of anatomical layers on OCT scans plays a crucial role for predictive models linking retinal structure to visual function. Our algorithm for
segmentation of OCT images could provide the basis for further studies on IRDs.
Assessment of Salivary MMP-8 and IL-1β for the Diagnosis of Periodontal Diseases in Pakistani Population
Authors: Kainat Rida , Ahmed Iftikhar , Alolaywi Abdullah Mohammed , Waheed Humera , Sultan Zohaib Khurshid , Moin Syed Faraz
Published: December 2023

Objective Clinical methods use the subjective diagnosis of periodontal diseases by visual observation that could result in differences and variability of diagnosis. The addition of specific markers could aid in the accurate diagnosis of the local population. The objective of the study was to target two of the major proteins for possible significance in such an approach.

Materials and Methods Unstimulated saliva samples were collected from 60 participants aged between 18 and 70 years. Three groups each with twenty participants were recruited into periodontitis, gingivitis, and healthy control.

Statistical Analysis The samples were analyzed using human enzyme-linked immunosorbent assay kits for matrix metalloproteinase-8 (MMP-8) and interleukin-1β (IL-1β).

Results SPSS version 20 was used to analyze the result. Posthoc analysis by Tukey's test revealed that MMP-8 levels were higher in gingivitis and periodontitis groups as compared with healthy controls. The test also revealed that IL-1β levels were higher in the periodontitis group compared with the healthy control and gingivitis group. Additionally, one-way analysis of variance analysis showed a significant effect on probing depth in gingivitis and periodontitis patients. The mean age of periodontitis group was significantly higher than other groups.

Conclusion Salivary biomarkers may provide useful diagnostic information and could be utilized as tests for periodontal disease screening, prognosis, and prediction.
Perfusion Dynamics during Secondary Flap Debulking with Liposuction
Authors: Geeroms Maxim , Lu Yun-Jui , Hsu Chung-Chen , Huang Ren-Wen , Lin Chih-Hung , Lin Cheng-Hung
Published: December 2023

Background Lower extremity trauma often necessitates reconstruction with flap transfer. One of the reconstructive goals is a thin soft tissue coverage with appropriate contour. Therefore, a secondary debulking of the flap is usually performed.

Methods Debulking through conventional lipectomy is compared with liposuction followed by excision of the defatted flap excess. Demographic data, surgical details, and postoperative outcomes are compared and analyzed. The perfusion dynamics of the flaps undergoing liposuction debulking are studied by means of perioperative indocyanine green fluorescence angiography, as well as postoperative laser Doppler imaging.

Results Patients undergoing lipectomy (n = 69; 57.5%) or liposuction (n = 51; 42.5%) debulking had a similar rate of postoperative complications. Partial necrosis was observed in 7.2% (lipectomy) versus 7.8% (liposuction) of flaps. Fluorescence angiography showed a substantial decrease in flap perfusion following the infiltration with an epinephrine-containing tumescent solution (74.3% ± 8.2% prior to infiltration versus 16.8% ± 7.1% after infiltration; p < 0.001), resulting in a dark flap appearance. Laser Doppler imaging confirmed the hypoperfusion on postoperative day 1.

Conclusion Secondary debulking of a lower extremity flap can be safely and efficiently performed through liposuction combined with peripheral excision of the defatted flap in a single stage. Perfusion studies may show a misleading hypoperfusion of the defatted flap, which does not accurately predict subsequent necrosis or complications.
Toward sustainable port development: an empirical analysis of China’s port industry using an ESG framework
Authors: Gu Xiyan , Zhu Yingjun , Zhang Jingxia
Published: December 2023

In recent years, the issue of sustainable development has become increasingly important in the port industry. As port policies are altered under decentralization and governance models, the application of corporate responsibility (CR) is expanding. It is now expected that ports take on environmental, social, and governance (ESG) responsibilities. This paper focuses on the application of an ESG framework to the port industry in China, with a specific emphasis on social responsibilities. By focusing on ESG-focal issues in the port industry, we establish a model for evaluating the sustainability of ports that takes into account the three dimensions of environment, society, and governance. An empirical analysis of Shanghai Port in China is presented to illustrate the application of the framework. The paper highlights the main contribution of the ESG framework to support sustainable port development and provides recommendations for promoting the implementation of ESG and sustainable development in the industry.
Exploring students’ beliefs about web-based collaborative learning and their practices: a qualitative case study of university English-as-a-foreign-language readers
Authors: Zhang Xiaodong
Published: December 2023

This semester-long qualitative case study, spanning 4 months, focused on an English reading course in which 20 university English-as-a-foreign-language readers were instructed to engage in web-based collaborative learning outside of class. The study drew on data resources including interviews with students, field notes on their web-based collaborative learning practices, and students’ written reflections. A thematic analysis of the data sources shows that the positivity of student readers’ beliefs about web-based collaborative learning (i.e., about web-based collaborative platforms and reading activities) changed over time but ultimately became stably positive. The change was found to be related to the interactions between their beliefs about web-based collaborative platforms and their beliefs about reading activities over time. The students’ beliefs about web-based collaborative learning were also found to be sensitive to factors regarding the students’ learning over time, including their prior learning experiences and their ongoing learning experiences. In the process, the students’ web-based collaborative learning practices were primarily driven by their positive beliefs and constrained by their negative beliefs although additional factors emerged over time from their learning process and intervened in the relationship between their beliefs and their learning. The implications of these findings on how to best engage students in web-based learning are discussed.
Two-dimensional electron gases as non-Newtonian fluids
Authors: Kryhin Serhii , Levitov Leonid
Published: December 2023

Two-dimensional electron systems offer an appealing platform to explore long-lived excitations arising due to collinear carrier scattering enabled by phase-space constraints at the Fermi surface. Recently it was found that these effects can boost excitation lifetimes over the fundamental bound set by Landau’s Fermi-liquid theory by a factor as large as (TF/T)α with α≈2. Long-lived degrees of freedom possess the capability to amplify the response to weak perturbations, producing lasting collective memory effects. This leads to non-Newtonian hydrodynamics in 2D electron fluids driven by multiple viscous modes with scale-dependent viscosity. We describe these modes as Fermi surface modulations of odd parity evolving in space and time, and discuss their implications for experimental studies of electron hydrodynamics.
The exotic ground state of the decorated honeycomb lattice
Authors: Kryvchikov O. O. , Laptiev D. V.
Published: December 2023

The study is focusing on the exploration of the magnetic properties of the frustrated decorated honeycomb lattices. The presence of geometrical frustration and C3 symmetry leads to an exotic ground state. Monte Carlo simulations and analytical calculations are used to analyze the system’s behavior. The dependence of the magnetization on the external field of the Ising model exhibits a step-like behavior, while the magnetization of the classical Heisenberg model has no plateau in the isotropic case. An efficient Hamiltonian is proposed to describe the properties of this system on the unfrustrated hexagonal lattice within the framework of the chiral Potts model. Within a specific range of fields, the state of the effective Hamiltonian aligns with that of the original Hamiltonian. The ground state configurations and degeneracy of the system are explored, revealing fractured stripe patterns separated by spins with opposite orientations. These findings contribute to the knowledge of the properties of decorated lattices, offering valuable insights for potential experimental and practical applications.
Germanium-OLED short-wave infrared-to-visible upconverters
Authors: Rao Tianyu , Qi Yawei , Hao Qun , Chen Menglu , Tang Xin , Mu Ge
Published: December 2023

Infrared-to-visible upconverters consisting of infrared photodetectors (PDs) with visible light-emitting diodes (LEDs) to directly visualize infrared images without intermediate electronics have stimulated research interest. However, existing upconverters mostly detect infrared only in the near-infrared region, preventing the extensive short-wave infrared (SWIR) application. Here, we innovatively integrate strong-SWIR-response n-type germanium (Ge)/indium tin oxide (ITO) PDs with phosphorescence organic LEDs (OLEDs) to realize the efficient upconversion of SWIR to green light through a simple fabrication process. The ITO layers not only construct Schottky heterojunction with the Ge to improve SWIR detection ability but also provide the photogenerated carriers transport channel from PDs to OLEDs. As a result, the Ge-OLED upconverters exhibit the efficient upconversion of SWIR and high p–p efficiency of 7%.
High Te discrepancies between ECE and Thomson diagnostics in high-performance JET discharges
Authors: Fontana M. , Giruzzi G. , Orsitto F. P. , de la Luna E. , Dumont R. , Figini L. , Kos D. , Maslov M. , Schmuck S. , Senni L. , Sozzi C. , Frigione D. , Garcia J. , Garzotti L. , Hobirk J. , Kappatou A. , Keeling D. , Lerche E. , Rimini F. , Van Eester D. , Maggi C. F. , Mailloux J. ,   JET Contributors
Published: December 2023

The present paper is dedicated to the study of the discrepancies encountered in electron temperature (Te) measurements carried out with electron cyclotron emission (ECE) and Thomson scattering (TS) diagnostics in the core of the JET tokamak. A large database of discharges has been collected, including high-performance scenarios performed with deuterium only and deuterium–tritium mixtures. Discrepancies have been found between core Te measurements taken with an X-mode ECE interferometer (TECE) and a LIDAR TS system (TLID) for Te>5 keV. Depending on the plasma scenario, TECE has been found to be systematically higher or lower than TLID. Discrepancies have also been observed between the peaks of the ECE spectrum in the second (X2) and third (X3) harmonic domains, even in high optical thickness conditions. These discrepancies can be interpreted as evidence of the presence of non-Maxwellian features in the electron energy distribution function (EEDF). In order to investigate the relation between the shape of the EEDF and the measured discrepancies, a model for bipolar perturbations of Maxwellian EEDF has been developed. The model allows analytical calculations of ECE absorption and emission coefficients; hence, the comparison of modeled ECE spectra with experimental data. The different experimental results observed for the various JET scenarios have been found to be qualitatively reproducible by adapting the model parameters, suggesting that bipolar distortions of the bulk EEDF could play a role in giving rise to the reported discrepancies between ECE and TS measurements.
Simultaneously measuring the dichroism and the dielectric response of an azobenzene-doped organic glass former
Authors: Dzik E. , Datin P. , Dognon J.-P. , Fajolles C. , Wiertel-Gasquet C. , Carrière D. , Ladieu F.
Published: December 2023

We have designed an experimental setup allowing to simultaneously measure both the dielectric response of a supercooled liquid and the dynamics of azobenzene chromophores dispersed in it. Both the azobenzene chromophores and the organic glass former have been synthesized with similar reaction paths: they are chemically similar, apart from the azobenzene group responsible for the strong optical absorption in the [350; 450 nm] range for the chromophores, while the embedding supercooled liquid is optically transparent. This material is deposited on transparent electrodes with an inter-electrode gap as small as 4 µm—obtained thanks to optical lithographic techniques. We show that our setup is sensitive enough to measure the coupling between the dielectric macroscopic response and the isomerization dynamics of 1% of chromophores excited by a 0.5–5 mW/cm2 light beam. We demonstrate that this coupling neither comes from the heating of the sample due to the light absorption nor from changes of the sample shape with light. Finally, we discuss the few physical effects, which may give rise to this coupling, and show that our experiment could test some recent predictions done in the framework of random first order transition theory of the glassy state.
Photothermal vortex interferometer with azimuthal complex spectra analysis for the measurement of laser-induced nanoscale thermal lens dynamics
Authors: Dong Jingtao , Zhang Tengda , Yang Lei , Zhang Yuzhong , Lu Rongsheng , Xie Xinglong
Published: December 2023

A photothermal vortex interferometer (PTVI) is proposed to fill the gap of full-field measurement of the laser-induced nanoscale thermal lens dynamics of optical elements. The PTVI produces a multi-ring petal-like interferogram by the coaxial coherent superposition of the high-order conjugated Laguerre–Gaussian beams. The non-uniform optical path change (OPC) profile resulting from the thermal lens causes the petals of the interferogram at the different radii to shift by the different azimuths. To demodulate such an interferogram, an azimuthal complex spectra analysis is presented by using a camera with a pixelated multi-ring pattern written on its sensor to extract multiple azimuthal intensity profiles synchronously from the interferogram. Therefore, the OPC profile can be determined dynamically from the complex spectra of the azimuthal intensity profiles at the main frequency components. An analytical thermophysical model of the thermal lens is given, and the basic principle of the azimuthal complex spectra analysis is revealed. A proof-of-concept experiment is demonstrated using a N-BK7 glass sample heated by a pump laser. The results verified that the PTVI achieves the measurement accuracy of 47 pm with a standard deviation of 358 pm (3σ) and can be used for full-field measurement of the nanoscale OPC profile caused by the thermal lens dynamics. Due to the picometer-scale accuracy of the PTVI, the absorption coefficient and thermal diffusivity of the glass sample were determined to be A0 = 0.126 m−1 and D = 5.63 × 10−7 m2 s−1, respectively, which agree with the nominal ones of A0 = 0.129 m−1 and D = 5.17 × 10−7 m2 s−1. Although the PTVI is only suitable for measuring the rotationally symmetric OPC, it shows less computation burden and hardware complexity, and it is proved to be a highly sensitive and effective tool in studying optical, thermo-physical, and mechanical properties of optical elements.
Combining three sources of optical anisotropy in a tunable open-access microcavity: From theory to experiment
Authors: Li Yiming , Luo Xiaoxuan , Guo Yaxin , Ren Jiahuan , Long Teng , Wang Bohao , Cai Yin , Guo Chaowei , Qin Yuanbin , Fu Hongbing , Zhang Yanpeng , Yun Feng , Liao Qing , Li Feng
Published: December 2023

Photonic spin–orbit (SO) coupling is an important physical mechanism leading to numerous interesting phenomena in the systems of microcavity photons and exciton-polaritons. We report the effect of SO coupling in a tunable open-access microcavity embedded with anisotropic active media. The SO coupling associated with the TE–TM splitting results in an emergent anisotropy, which further leads to fine energy splittings allowing clear observation of the full set of eigenstates, in sharp contrast with the isotropic situation which leads to the isotropic eigenstates of spin vortices. We show that the photonic potential can be engineered by playing with the relation between the emergent anisotropy and the cavity ellipticity. All the experimental results are well reproduced by the degenerate perturbation theory. Our results constitute a significant extension to the research field of microcavity spinoptronics, with potential applications in polarization control and optical property measurement of photonic devices and materials.
Study on oxidation behaviors of Zr–Sn–Nb alloy in water steam at 1250 °C
Authors: Tang Dewen , Che Zhiyuan , Jiang Rui
Published: December 2023

To investigate the effect of different oxidation times on the oxidation behavior of Zr–Sn–Nb alloy in a high-temperature steam environment at 1250 °C, steam oxidation tests were conducted on the Zr–Sn–Nb alloy at 1250 °C for durations ranging from 100 to 5000 s. Microstructural and elemental composition analyses of the Zr–Sn–Nb alloy were carried out using scanning electron microscopy, energy-dispersive x-ray spectroscopy, and optical microscopy. The results showed that in the initial stages of oxidation (0–1000 s), the weight gain per unit area followed a parabolic trend. After 2500 s of oxidation, the weight gain rate significantly increased. In the later stages of oxidation (after 4000 s), the weight gain curve transitioned from a parabolic shape to a linear law. With increasing oxidation time, the thickness of the oxide layer gradually increased. In the early stages (0–2500 s), the growth rate of the oxide layer thickness was relatively slow, but the appearance of micro-pores and cracks was observed. However, after 2500 s, the steam oxidation rate of the Zr–Sn–Nb alloy significantly accelerated, leading to fracture and failure of the alloy specimens. The change in oxide layer thickness over time followed a parabolic law before 2500 s and a linear law after 2500 s. The growth curve of the α-Zr(O) layer within 5000 s also followed a parabolic law.
Regional internal tide models need prudent eddy viscosity selections for dependable estimations
Authors: Li Bingtian , Pan Haidong , Teng Fei , Wei Zexun , Lv Xianqing
Published: December 2023

Many studies on internal tides (ITs) are conducted through numerical simulations. One major challenge involves the large discrepancies in baroclinic energetics in regional seas, such as the Luzon Strait (LS). These discrepancies may partially be related to the variation in eddy viscosity selections. Evident increase in eddy viscosities can affect the baroclinic energy balances and reduce simulation error in the LS. Finally, horizontal mixing parameterization schemes are found to be significant in improving the performance of regional IT modeling. The finding highlights the significance of eddy viscosity, which may make contributions to improve regional IT estimations.
Improving the selector characteristics of ovonic threshold switch via UV treatment process
Authors: Seo Yoori , Lee Jangseop , Ban Sanghyun , Kim Dongmin , Han Geonhui , Hwang Hyunsang
Published: December 2023

In this study, we investigated the influence of ultraviolet (UV) treatment on the ovonic threshold switch (OTS) to improve its selector properties. Our findings demonstrate that iteratively applying UV treatment during the film deposition phase considerably improves device characteristics compared to a single UV treatment. Consequently, this process provided a significant decrease in the forming voltage, maintaining outstanding switching features, with an off-state current of approximately 2 nA. Furthermore, the refined UV treatment process resulted in an impressive 45% improvement in threshold voltage drift characteristics and facilitated excellent switching uniformity. X-ray photoelectron spectroscopy analysis revealed alterations in the bonding structure of the Si–Te–As–Ge film after UV exposure. Specifically, a transition was observed from unstable homopolar bonds, such as As-As or Te–Te, to their more stable heteropolar equivalents, such as As–Te. These results highlight the potential of UV treatment as an effective method for enhancing the OTS performance.
Revealing quasi-excitations in the low-density homogeneous electron gas with model exchange–correlation kernels
Authors: Kaplan Aaron D. , Ruzsinszky Adrienn
Published: December 2023

Time-dependent density functional theory within the linear response regime provides a solid mathematical framework to capture excitations. The accuracy of the theory, however, largely depends on the approximations for the exchange–correlation (xc) kernels. Away from the long-wavelength (or q = 0 short wave-vector) and zero-frequency (ω = 0) limit, the correlation contribution to the kernel becomes more relevant and dominant over exchange. The dielectric function, in principle, can encompass xc effects relevant to describe low-density physics. Furthermore, besides collective plasmon excitations, the dielectric function can reveal collective electron–hole excitations, often dubbed “ghost excitons.” Besides collective excitons, the physics of the low-density regime is rich, as exemplified by a static charge-density wave that was recently found for rs > 69, and was shown to be associated with softening of the plasmon mode. These excitations are seen to be present in much higher density 2D homogeneous electron gases of rs ≳ 4. In this work, we perform a thorough analysis with xc model kernels for excitations of various nature. The uniform electron gas, as a useful model of real metallic systems, is used as a platform for our analysis. We highlight the relevance of exact constraints as we display and explain screening and excitations in the low-density region.
High frame-rate imaging of the shape oscillations and spreading dynamics of picolitre droplets impacting on a surface
Authors: McCarthy Lauren P. , Reid Jonathan P. , Walker Jim S.
Published: December 2023

The post-impact dynamics and spreading rates of picolitre liquid droplets on surfaces are critical to many practical and industrial applications, as well as respiratory disease transmission mechanisms. Here we use a high framerate imaging method to explore the shape oscillations and spreading of individual ∼10–180 pl volume droplets (corresponding to ∼30–70 μm in initial droplet diameter) impacting on a surface under ambient conditions with 10 μs temporal resolution. The method allows the surface tension to be accurately extracted from the measured frequency of post-impact shape oscillations for sessile droplets in this size range with surface tensions greater than 40 mN m−1 and viscosities up to at least 3.2 mPa s. The Tanner's law model for predicting sessile droplet spreading rates provides an accurate account of the “steady-state” spreading rate for all droplets with surface tensions in the range 22–73 mN m−1 studied here. However, Tanner's law does not account for the delay in the onset of spreading observed for droplets in this size range, caused by competition between shape oscillations and spreading governing the morphology at short time periods, particularly for surface tensions >22 mN m−1.
Electromagnetohydrodynamic (EMHD) flow through porous media—Multiscale approach
Authors: Majumdar Promasree , Dasgupta Debabrata
Published: December 2023

Electromagnetohydrodynamic (EMHD) flow in porous media is recently gaining substantial attention from researchers. EMHD involves analyzing the combined effects of electric and magnetic fields on the behavior of fluid flow through a medium. The effective permeability of porous materials is of great interest for many environmental and industrial applications. The present study focuses on the modeling of single-phase fluid flow in porous media under combined effects of electric and magnetic fields at the pore scale by employing a two-scale computational homogenization technique. The primary objective of this study is to establish a definition of “electromagnetopermeability” that accurately characterizes the effective permeability of a porous medium under the EMHD effects. Additionally, the study investigates the impact of wall zeta potential, Debye length, and the intensity of external magnetic and electric fields, represented by the Hartmann number and the non-dimensional parameter S, respectively, on the electromagnetopermeability tensor within an idealized three-dimensional periodic porous domain. It is observed that the EM-permeability is significantly affected by the existence of the flow-assisting and flow-opposing components of the Lorentz force term in the momentum equation. The implications of this research extend to several industries, including geology, medicine, chemistry, and energy conversion.
Ultrafast dynamics of a photoinduced phase transition in single-crystal trititanium pentoxide
Authors: Hatanaka Shuhei , Tsuchiya Taro , Ichikawa Shuhei , Yamasaki Jun , Sato Kazuhisa
Published: December 2023

We investigate photoinduced phase transition of Ti3O5 using the pump-probe method in an ultrafast electron microscope. We measured time-resolved electron diffraction patterns of single-crystal lamellae of Ti3O5 excited by the femtosecond laser at the wavelength of 800 and 400 nm. Under 800 nm laser excitation, the photoinduced phase transition from the β-phase to the λ-phase with a similar timescale to previous measurements conducted using nanocrystals was observed. This indicates that the photoinduced phase transition is not a phenomenon influenced by the material surface, size, or boundary, but an intrinsic property in a bulk crystal of Ti3O5. The photoinduced phase transition was not detected, when excited by the laser at the wavelength of 400 nm. The results are discussed based on the electronic states of β-Ti3O5 and λ-Ti3O5. The density of the dissociated interatomic bonds between Ti at the specific site should be an important factor for triggering the photoinduced phase transition.
Dissociation line and driving force for nucleation of the nitrogen hydrate from computer simulation
Authors: Algaba Jesús , Torrejón Miguel J. , Blas Felipe J.
Published: December 2023

In this work, we determine the dissociation line of the nitrogen (N2) hydrate by computer simulation using the TIP4P/Ice model for water and the TraPPE force field for N2. We use the solubility method proposed recently by some of us to evaluate the dissociation temperature of the hydrate at different pressures, from 500 to 1500 bar. Particularly, we calculate the solubility of N2 in the aqueous solution when it is in contact with a N2-rich liquid phase and when in contact with the hydrate phase via planar interfaces as functions of temperature. Since the solubility of N2 decreases with temperature in the first case and increases with temperature in the second case, both curves intersect at a certain temperature that determines the dissociation temperature at a given pressure. We find a good agreement between the predictions obtained in this work and the experimental data taken from the literature in the range of pressures considered in this work. From our knowledge of the solubility curves of N2 in the aqueous solution, we also determine the driving force for nucleation of the hydrate, as a function of temperature, at different pressures. In particular, we use two different thermodynamic routes to evaluate the change in chemical potential for hydrate formation. Although the driving force for nucleation slightly decreases (in absolute value) when the pressure is increased, our results indicate that the effect of pressure can be considered negligible in the range of pressures studied in this work. To the best of our knowledge, this is the first time the driving force for nucleation of a hydrate that exhibits crystallographic structure sII, along its dissociation line, is studied from computer simulation.
Comparison of aerodynamic performance of trains running on bridges under crosswinds using various motion modes
Authors: Zhang Jie , Ding Yansi , Wang Fan , Xiang Nanshen , Xu Ao , Chen Zhengwei , Tang Mingzan
Published: December 2023

The high-speed railway bridge, accounting for over 50% of railway lines, plays an important role in high-speed railways. When the train runs at high speed on these bridges, the strong winds will directly pose a risk to the safety of train operation, even causing train overturning accidents. Therefore, it is significantly urgent to accurately simulate the relative motion of the train-bridge system in crosswind environment. An improved delayed detached-eddy simulation study based on the shear stress transfer k-omega (I-ω) turbulence model was used to analyze the aerodynamic characteristics of trains running on bridges under two relative motion modes, i.e., the static synthesis method (SSM) and the dynamic decomposition method (DDM), and the variation rule of train aerodynamic loads. The differences of aerodynamic forces, surface pressure distributions, and flow characteristics around the train body under two motions were discussed. The results show that the applied velocity-inlet boundaries in two relative train-bridge motion modes under crosswinds lead to a large difference in the flow characteristics around bridges. Compared with the SSM, the DDM generates more small-scale vortices in the leeward side of the train, causes more disturbances, and enhances the flow instability. Under the DDM, the side force coefficient and lift force coefficient of the train are decreased by 1.99%, 66.67% (Train on the windward side) and 24.47%, 48.24% (Train on the leeward side), respectively, as compared to the SSM. The achievements obtained in the current study can provide data support for the operation standard of high-speed trains traveling on bridges.
Characteristics of interacting carbon-antisite-vacancies in 4H silicon carbide
Authors: Liu Qingsong , Deng Jun , Sun Yong , Wang Zhengjia , Song Shuwei
Published: December 2023

Spin defects in semiconductors have demonstrated promising electronic structures for potential applications in quantum computing and sensing. Among various proposed quantum byte systems, spin defects in silicon carbide have attracted significant attention due to several advantages they offer over other options. In this study, we investigate carbon-antisite-vacancy defects in 4H silicon carbide through ab initio density functional theory calculations. With the HSE06 functionals, the ab initio computation can predict much more accurate electronic structures. However, the corresponding computational cost is high, especially for supercells consisting of several hundreds of atoms. In this investigation, the carbon-antisite-vacancy defect is studied by using a high-performance computing cluster, with a specific focus on supercells that encompass two such defects. The extension of a single carbon-antisite-vacancy defect is depicted by referring to the spin density distribution. Different defect types show similar spin density patterns. Based on the single defect characteristics, supercells with paired carbon-antisite-vacancy defects are created. It is found that the binding energy can reach 2 eV for overlapping defects. In the case of insignificant overlap of the corresponding single defects, the ground state magnetic moment is 4 µB, accompanied by a negligible binding energy. However, if there is a significant overlap of the spin density, the magnetic moment changes to 2 µB. These findings can serve as helpful references for the study of spin defects in 4H silicon carbide, particularly in the potential carbon-antisite-vacancy application research.
Dispersion engineering of metalenses
Authors: Yu Haoyi , Xie Zhaoyang , Li Chenhao , Li Chi , de S. Menezes Leonardo , Maier Stefan A. , Ren Haoran
Published: December 2023

Optical dispersion, the variation of the speed of light with frequency in a material, presents significant challenges in modern optical systems, including chromatic aberration and pulse signal distortion. Traditional approaches to dispersion engineering of an optical lens system require the use of a set of sub-lenses of opposite dispersion properties, largely increasing the overall lens thickness. Ultrathin metasurfaces offer unprecedented control over optical wavefronts with advanced functionalities. Developing achromatic metalenses has thereby emerged as a timely research topic for metasurface research. This Perspective article provides a comprehensive overview of dispersion engineering methods in metalenses, including the use of 2D and 3D meta-atoms fabricated from planar lithography and 3D laser lithography methods, respectively. We compare key figures of merit of achromatic metalenses developed for different wavelength ranges and discuss recent inverse design of large-scale achromatic metalenses. We believe advanced machine learning methods as well as hybrid nanofabrication of diffractive metalenses, refractive lenses, and metamaterials-like spaceplates could offer promising avenues for overcoming current challenges and eventually push ultrathin achromatic optics to practical applications in optics-related fields.
Contracted description of driven degenerate multilevel quantum systems
Authors: Xu Xiangyu , Sun Kewei , Gelin Maxim F. , Zhao Yang
Published: December 2023

We formulate a contraction theorem that maps quantum dynamics of a multilevel degenerate system (DS) driven by a time-dependent external field to the dynamics of the corresponding contracted non-degenerate system (CNS) of lower dimension, provided transitions between each pair of degenerate levels in the DS have identical transition dipole moments. The theorem is valid for an external field of any strength and shape, with and without rotating wave approximation in the system–field interaction. It establishes explicit relations between DS and CNS observables, significantly simplifies numerical calculations, and clarifies physical origins of the field-induced DS dynamics.