bluuebunny/crossref_metadata_2025 huggingface dataset:
Hunting for gamma-ray emission from fast radio bursts
Authors: Principe G. , Di Venere L. , Negro M. , Di Lalla N. , Omodei N. , Di Tria R. , Mazziotta M. N. , Longo F.
Published: June 2023

Context.Fast radio bursts (FRBs) are a recently discovered class of GHz-band, ms-duration, Jansky-level-flux astrophysical transients. Although hundreds of models have been proposed so far for FRB progenitors (the most popular ones involve magnetars), their physical origin and emission mechanism are still a mystery, making them one of the most compelling problems in astrophysics.

Aims.FRBs are caused by astrophysical processes that are not yet understood. Exploring their high-energy counterpart is crucial for constraining their origin and emission mechanism.

Methods.Thanks to more than 13 years of gamma-ray data collected by the Large Area Telescope on board theFermiGamma-ray Space Telescope, and to more than 1000 FRB events (from 561 non-repeating and 22 repeating sources), one of the largest samples created thus far, we performed the largest and deepest search for high-energy emission from FRB sources to date (between 100 MeV and 1 TeV). In addition to the analysis involving individual FRB events on different timescales (from a few seconds up to several years), we performed, for the first time, a stacking analysis on the full sample of FRB events as well as a search for triplet photons in coincidence with the radio event.

Results.We do not detect significant emission, reporting the most stringent constraints, on short timescales, for the FRB-like emission from SGR 1935+2154 withEγ < 1041erg, corresponding to a factorη < 107with respect to the emitted radio energy. Similarly, for the stacked signal of steady emission from all repeaters, the obtained upper limit (UL) on the FRBs luminosity (Lγ < 1.6 × 1043erg s−1) is more than two orders of magnitude lower than those derived from the individual sources. Finally, no individual or triplet photons have been significantly associated with FRB events. We derived the LAT ms-sensitivity to be ∼0.3 ph cm−2s−1and constrained the gamma-ray energyEγ,δT = 1 ms ≲ 1047(DL/150 Mpc)2erg, ruling out a gamma-ray-to-radio energy ratio greater than 109on ms timescales.

Conclusions.The results reported here represent the most stringent UL reported so far on the high-energy emission from FRBs on short and long time scales, as well as on cumulative emission and individual photon searches. While the origin of FRBs is still unclear, our work provides important constraints for FRB modelling, which might shed light on their emission mechanism.
Robustness of polynomial stability with respect to sampling
Authors: Wakaiki Masashi
Published: June 2023

We provide a partially affirmative answer to the following question on robustness of polynomial stability with respect to sampling: “Suppose that a continuous-time state-feedback controller achieves the polynomial stability of the infinite-dimensional linear system. We apply an idealized sampler and a zero-order hold to a feedback loop around the controller. Then, is the sampled-data system strongly stable for all sufficiently small sampling periods? Furthermore, is the polynomial decay of the continuous-time system transferred to the sampled-data system under sufficiently fast sampling?” The generator of the open-loop system is assumed to be a Riesz-spectral operator whose eigenvalues are not on the imaginary axis but may approach it asymptotically. We provide conditions for strong stability to be preserved under fast sampling. Moreover, we estimate the decay rate of the state of the sampled-data system with a smooth initial state and a sufficiently small sampling period.
A study of the local dynamics of modified Patankar DeC and higher order modified Patankar–RK methods
Authors: Izgin Thomas , Öffner Philipp
Published: June 2023

Patankar schemes have attracted increasing interest in recent years because they preserve the positivity of the analytical solution of a production–destruction system (PDS) irrespective of the chosen time step size. Although they are now of great interest, for a long time it was not clear what stability properties such schemes have. Recently a new stability approach based on Lyapunov stability with an extension of the center manifold theorem has been proposed to study the stability properties of positivity-preserving time integrators. In this work, we study the stability properties of the classical modified Patankar–Runge–Kutta schemes (MPRK) and the modified Patankar Deferred Correction (MPDeC) approaches. We prove that most of the considered MPRK schemes are stable for any time step size and compute the stability function of MPDeC. We investigate its properties numerically revealing that also most MPDeC are stable irrespective of the chosen time step size. Finally, we verify our theoretical results with numerical simulations.
Marginal-utility-oriented optimization model for collaborative medical supply rebalancing and allocating in response to epidemics
Authors: Gao Xuehong , Cao Cejun , Chen Zhijin , Huang Guozhong , Jiang Huiling , Zhou Liang
Published: June 2023

Large-scale epidemics impose significant burdens globally and cause an imbalance of medical supplies among different regions owing to the dissimilarly and unevenly distributed prevalence of the infection. Along with rebalancing the limited medical supplies to meet the demand and supply requirements, ensuring that the supplies are allocated to support the affected regions is also important. Hence, this study focuses on the collaborative medical supply rebalancing and allocating process to balance the demand and supply. The law of diminishing marginal utility is incorporated in this study to quantify the principle of fairness in rebalancing and allocating medical supplies. Accordingly, under uncertainty, a marginal-utility-oriented optimization model is proposed to formulate the rebalancing and allocation of collaborative medical supplies. Because the proposed model is nonlinear and computationally intractable, a linearization approach is adopted to obtain the global optimum that supports decision-making in response to epidemics. Furthermore, a real case study of the United States is implemented, where the sensitivity analysis of critical parameters is conducted on the coronavirus disease 2019. Computational results indicate that additional medical supplies, stock levels, and scenario constructions significantly influence the supply/demand point identification and outgoing/incoming shipments. Moreover, this study not only validates the effectiveness and feasibility of the method but also highlights the importance of incorporating the law of diminishing marginal utility into the collaborative medical supply rebalancing and allocating problem.
Temperaturmanagement auf der neonatologischen Intensivstation
Authors: Bouws Pia , Joos Katja
Published: June 2023

Hypothermien und Temperaturschwankungen bei extrem frühgeborenen Säuglingen < 28. Schwangerschaftswoche haben weitreichende Auswirkungen auf den gesamten Organismus und beeinflussen das Outcome. Um Temperaturschwankungen zu reduzieren und Unsicherheiten bei der thermoneutralen Versorgung von früh- und reifgeborenen Säuglingen zu minimieren, entwickelten Pflegende am Klinikum Stuttgart eine evidenzbasierte Leitlinie zum Temperaturmanagement, die anhand eines evidenzbasierten Theoriemodells in die Praxis implementiert wurde.
Catalytic Dehydrative Transformations Mediated by Moisture-Tolerant Zirconocene Triflate
Authors: Lundberg Helena , Margarita Cristiana , Di Francesco Davide
Published: June 2023

Zirconocene triflate is a powerful moisture-tolerant catalyst for activation of C–O bonds in carboxylic acids and alcohols in the absence of water scavenging techniques. Herein, an overview of the use of this robust metal complex for direct amidation, esterification, and etherification is presented, along with a discussion on mechanistic aspects of the transformations and the catalyst class.
Iodine-Catalyzed Simple and Efficient Synthesis of 1,3,5-Triarylbenzenes and 2,3-Dihydrobenzofuran Derivatives under Mild Reaction Conditions
Authors: Meng Xiangzhen , Cheng Dong , Li Dongmei , Jie Sunying , Liu Yifan , Jiao Xiaoqing
Published: June 2023

The I2-catalyzed cyclization reaction of chalcones and 2-aryl propionaldehydes or isobutyraldehyde has been developed for the synthesis of 1,3,5-triarylbenzenes and 2,3-dihydrobenzofuran derivatives. This reaction tolerates a wide range of functional groups. Moreover, this method features an inexpensive catalyst and available starting materials.
Incidental Finding of Arteria Lusoria in COVID-19 Patient with Aortic Thrombus Complicated by Recurrent Limb Ischemia
Authors: Khedija Soumer , Nadia Azabou , Houcine Horchani , Mouna Bousnina , Amine Jemel
Published: June 2023

Coronavirus disease causes a hypercoagulable state with endothelial inflammation. These conditions can produce embolic complications. Thrombosis can occur in different locations and may lead to ischemic stroke and ischemic limb.

We report the case of a 64-year-old woman with recent severe acute respiratory syndrome coronavirus 2 pneumonia who was admitted to the hospital due to a giant floating thrombus in the ascending aorta with multiple ischemic events. Aortic computed tomography angiogram revealed an aberrant right subclavian artery associated with bicarotid trunk that might have protected carotid arteries from embol migration. Thrombosis is a rare clinical presentation in coronavirus disease 2019 infection but with serious complications that must be kept in mind to detect and avoid morbidities like ischemic stroke.
Malignant Pleural Effusions in the Era of Immunotherapy and Antiangiogenic Therapy
Authors: Wong Terrence , Fuld Alexander D. , Feller-Kopman David J.
Published: June 2023

Malignant pleural effusions (MPE) have historically been associated with a poor prognosis, and patients often require a series of invasive procedures and hospitalizations that significantly reduce quality of life at the terminus of life. However, advances in the management of MPE have coincided with the era of immunotherapies, and to a lesser extent, antiangiogenic therapies for the treatment of lung cancer. Landmark studies have shown these drugs to improve overall survival and progression-free survival in patients with lung cancer, but a paucity of phase III trial data exists for the impact of immune checkpoint inhibitors (ICI) on lung cancers associated with MPE. This review will focus on the leading studies investigating the impact of ICI and antiangiogenic therapies in patients with lung cancer and MPE. The diagnostic and prognostic values of vascular endothelial growth factor and endostatin expression levels in malignancy will also be discussed. These advancements are changing the paradigm of MPE management from palliation to treatment for the first time since 1767 when MPE was first reported. The future holds the promise of durable response and extended survival in patients with MPE.
Genesis of a Fact: Tay-Sachs Disease as a “Simple Recessive”
Authors: Lubinsky Mark
Published: June 2023

“Obvious” recessive inheritance of Tay-Sachs disease (TSD; OMIM # 272800) took over half a century to be established. Points now taken for granted were problematic, that: (1) TSD is a biological entity, not an artificial selection of concurrent findings, (2) manifestations have narrow limits, (3) it was not part of a spectrum of disorders, and can be differentiated from other conditions, (4) it will not change to another disease, (5) it is due to a single specific gene, (6) there are no secondary causes, (7) the gene has no apparent clinical effects unrelated to TSD, and (8) the gene is inherited only as a clinical recessive. To a large extent, resolution reflected biochemical understanding that took until mid-20th century, and beyond, to change how physicians viewed diseases in general. With this, biochemical carrier screening and prenatal biochemical diagnosis have become routinely available, and it is a model for carrier population screening, while gene therapy for the disease has been reported with some degree of success. Here, the history of medical ideas about TSD and its inheritance are reviewed to show how it achieved its current status as a distinct recessive disorder.
Hemoglobin A1c as a Substitute for Oral Glucose Testing in Early Pregnancy Screening
Authors: Crimmins Sarah D. , Martin Lucille M. , Myers Madalyn , Elsamadicy Emad , Quebedeaux Tabitha M. , Desai Andrea N. , Kopelman Jerome N.
Published: June 2023

Objective Current recommendations for individuals with risk factors for gestational diabetes mellitus (GDM) call for screening in early pregnancy. However, there is currently no clear consensus on a specific screening modality. This study evaluates whether a hemoglobin A1c (HbA1c) screening in individuals with risk factors for gestational diabetes (GDM) could be used instead of an early 1-hour glucose challenge test (GCT). We hypothesized that the HbA1c could replace 1-hour GCT in early pregnancy evaluation

Study Design This is a prospective observational trial at a single tertiary referral center of women with at least one risk factor for GDM who were screened at <16 weeks of gestation with both 1-hour GCT or HbA1c. Exclusion criteria include: previous diagnosis of diabetes mellitus, multiple gestation, miscarriage, or missing delivery information. The diagnosis of GDM was made by a 3-hour 100-g glucose tolerance test, using the Carpenter–Coustan criteria (at least two results >94, 179, 154, and 139 mg/dL for fasting, 1-, 2-, and 3-hour values, respectively), 1-hour GCT > 200 mg/dL, or HbA1c > 6.5%.

Results A total of 758 patients met inclusion criteria. A total of 566 completed a 1-hour GCT and 729 had an HbA1c collected. The median gestational age at testing was 91/7 weeks (range: 40/7–156/7 weeks]. Twenty-one participants were diagnosed with GDM at <16 weeks' GA. The receiver operating characteristic (ROC) curves identified the optimal valves for a positive screen for an HbA1c > 5.6%. The HbA1c had a sensitivity of 84.2%, a specificity of 83.3%, and a false positive rate of 16.7% (p < 0.001). The area under the ROC curve for the HbA1c was 0.898. Gestational age of delivery was slightly earlier with individuals with an elevated HbA1c but no other changes in delivery or neonatal outcomes. Contingent screening improved specificity (97.7%) and decreased false positive rate to 4.4%.

Conclusion HbA1c may be a good assessment in early pregnancy for gestational diabetes.

Key Points
Tuning terahertz emission generated by anomalous Nernst effect in ferromagnetic metal
Authors: Zhang Hui , Feng Zheng , Li Guansong , Zhang Liang , Chen Xiaobing , Bai He , Sun Song , Tang Jin , Zhang Jine , Han Furong , Yang Huaiwen , Tan Wei , Chen Yuansha , Hu Fengxia , Cai Jianwang , Guo Liang , Shin Sunmi , Zhao Weisheng , Shen Baogen , Sun Jirong
Published: June 2023

Despite intensive research, the mechanism determining the terahertz (THz) emission of the ferromagnetic (FM) metallic monolayers remains elusive. Here, we report on the results of a systematic investigation on the THz emission generated by pumping Ni80Fe20 monolayers on Al2O3 substrates with a femtosecond laser. We found solid evidence that the THz emission is dominated by the anomalous Nernst effect (ANE), in which a transient spin-polarized charge current can be induced by an ultrafast electron temperature gradient on the picosecond timescale, outputting THz emission. We found a polarity reversal of the THz waveform after the introduction of a SiO2 buffer layer to the sample and found that, based on ultrafast temperature simulation, it was a consequence of direction reversal of temperature gradient. Comparing the THz emission of different FM monolayers further confirms that the THz polarity also strongly depends on the sign of the ANE coefficient. These phenomena unambiguously indicate that the ANE plays a decisive role in the process of THz emission. The present work shows the importance of ultrafast spin caloritronics for a spintronic THz emitter. The principle demonstrated here can be applied to other FM metallic materials.
Deformation of optical solitons in a variable-coefficient nonlinear
Schrödinger equation with three distinct PT-symmetric potentials and modulated
nonlinearities
Authors: Manikandan K. , Sakkaravarthi K. , Sudharsan J. B. , Aravinthan D.
Published: June 2023

We investigate deformed/controllable characteristics of solitons in inhomogeneous parity-time (PT)-symmetric optical media. To explore this, we consider a variable-coefficient nonlinear Schrödinger equation involving modulated dispersion, nonlinearity, and tapering effect with PT-symmetric potential, which governs the dynamics of optical pulse/beam propagation in longitudinally inhomogeneous media. By incorporating three physically interesting and recently identified forms of PT-symmetric potentials, namely, rational, Jacobian periodic, and harmonic-Gaussian potentials, we construct explicit soliton solutions through similarity transformation. Importantly, we investigate the manipulation dynamics of such optical solitons due to diverse inhomogeneities in the medium by implementing step-like, periodic, and localized barrier/well-type nonlinearity modulations and revealing the underlying phenomena. Also, we corroborate the analytical results with direct numerical simulations. Our theoretical exploration will provide further impetus in engineering optical solitons and their experimental realization in nonlinear optics and other inhomogeneous physical systems.
Development of the high energy engineering X-ray (HEX) superconducting wiggler, magnetic measurement, installation, and commissioning
Authors: Tanabe T. , Corwin T. , Hidas D. , Musardo M. , Migliorino D. , Rank J. , Seegitz M. , Todd R. , Hidaka Y. , Hobl A. , Grau A.
Published: June 2023

The High energy Engineering X-ray (HEX) diffraction beamline at the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Lab (BNL) is the first high-energy beamline capable of reaching 200 keV for a monochromatic beam. With the 3 GeV electron beam energy for the NSLS-II ring, only the superconducting wiggler (SCW) producing greater than 4 T peak field can cover these ranges with a sufficient number of photons. The 1.2 m-long HEX-SCW has a period length of 70 mm and a field strength on-axis of 4.3 T. It utilizes no liquid helium, and the vertical aperture size of the electron beam vacuum chamber is 8 mm. Unlike regular undulators/wigglers, there is no standard configuration for the magnetic measurement system for superconducting insertion devices. The NSLS-II Insertion Devices group has developed, in collaboration with the vacuum group, a novel in-vacuum Hall mapper with a 1.75 m in-vacuum linear motor and an in-vacuum flip coil system utilizing many commercial-off-the-shelf products. The measurements were conducted at the BNL, and the device was installed in the ring and commissioned. This paper provides a description of the SCW and its magnetic measurement systems, as well as a brief account of the installation and commissioning efforts.
Wake-up free ferroelectric hafnia-zirconia capacitors fabricated via
vacuum-maintaining atomic layer deposition
Authors: Hsain H. Alex , Lee Younghwan , Lomenzo Patrick D. , Alcala Ruben , Xu Bohan , Mikolajick Thomas , Schroeder Uwe , Parsons Gregory N. , Jones Jacob L.
Published: June 2023

Ferroelectric hafnium-zirconium oxide (HZO) is an excellent candidate for low-power non-volatile memory applications due to its demonstrated ferroelectricity at the nanoscale and compatibility with silicon-based technologies. The interface of HZO in contact with its electrode, typically TiN in a metal–ferroelectric–metal (MFM) capacitor configuration, is of particular interest because factors, such as volume confinement, impurity concentration, interfacial layers, thermal expansion mismatch, and defect trapping, are believed to play a crucial role in the ferroelectric performance of HZO-based devices. Processing variables, such as precursor type, oxygen source, dose duration, and deposition temperature, are known to strongly affect the quality of the oxide–metal interface. However, not many studies have focused on the effect of breaking or maintaining vacuum during MFM deposition. In this study, sequential, no-atmosphere processing (SNAP) is employed to avoid atmospheric exposure, where electrode TiN and ferroelectric HZO are deposited sequentially in the atomic layer deposition chamber without breaking vacuum. The effect of breaking vacuum during the sequential deposition steps is elucidated by fabricating and characterizing MFM capacitors with and without intentional vacuum breaks prior to the deposition of the HZO and top TiN. Using x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry (ToF-SIMS), we reveal that breaking vacuum after bottom TiN electrode deposition leads to interfacial oxidation and increased carbon contamination, which preferentially stabilizes the non-ferroelectric tetragonal phase and lead to diminished remanent polarization. Avoiding carbon impurities and interfacial TiOx at the HZO and TiN interface using SNAP leads to heightened remanent polarization, reduced leakage current density, and elimination of the wake-up effect. Our work highlights the effect of vacuum breaking on the processing-structure-properties of HZO-based capacitors, revealing that maintaining vacuum can significantly improve ferroelectric properties.
Transitional cluster dynamics in a model for delay-coupled chemical oscillators
Authors: Keane Andrew , Neff Alannah , Blaha Karen , Amann Andreas , Hövel Philipp
Published: June 2023

Cluster synchronization is a fundamental phenomenon in systems of coupled oscillators. Here, we investigate clustering patterns that emerge in a unidirectional ring of four delay-coupled electrochemical oscillators. A voltage parameter in the experimental setup controls the onset of oscillations via a Hopf bifurcation. For a smaller voltage, the oscillators exhibit simple, so-called primary, clustering patterns, where all phase differences between each set of coupled oscillators are identical. However, upon increasing the voltage, secondary states, where phase differences differ, are detected, in addition to the primary states. Previous work on this system saw the development of a mathematical model that explained how the existence, stability, and common frequency of the experimentally observed cluster states could be accurately controlled by the delay time of the coupling. In this study, we revisit the mathematical model of the electrochemical oscillators in order to address open questions by means of bifurcation analysis. Our analysis reveals how the stable cluster states, corresponding to experimental observations, lose their stability via an assortment of bifurcation types. The analysis further reveals complex interconnectedness between branches of different cluster types. We find that each secondary state provides a continuous transition between certain primary states. These connections are explained by studying the phase space and parameter symmetries of the respective states. Furthermore, we show that it is only for a larger value of the voltage parameter that the branches of secondary states develop intervals of stability. For a smaller voltage, all the branches of secondary states are completely unstable and are, therefore, hidden to experimentalists.
PLD of α-Ga2O3 on m-plane Al2O3: Growth regime, growth process, and structural properties
Authors: Petersen Clemens , Vogt Sofie , Kneiß Max , von Wenckstern Holger , Grundmann Marius
Published: June 2023

Phase-pure α-Ga2O3 thin films with high surface quality and crystallinity have been grown on m-plane sapphire using pulsed laser deposition (PLD). Therefore, the influence of growth temperature, oxygen background pressure, and film thickness on the structural properties is investigated to determine the growth window for phase-pure corundum structured α-Ga2O3. Samples were analyzed using x-ray diffraction (XRD), atomic force microscopy (AFM), and spectroscopic ellipsometry measurements. A distinct growth window in favor of phase-pure (10.0)-oriented α-Ga2O3 for growth temperatures above 480 °C and low oxygen partial pressures p(O2) of 3 × 10−4 mbar is identified. The growth rate increases significantly with increasing oxygen pressure. Furthermore, it shows an Arrhenius-like decrease for lower temperatures, caused by the increasing desorption of volatile Ga2O suboxides. It was found that for thicker layers, the growth of monoclinic β-Ga2O3 is promoted likely facilitated by the c-facets of the α-Ga2O3 grains. This leads to a (010)-oriented island growth corroborated by stripe-like features in AFM scans and a corresponding in-plane orientation confirmed by XRD ϕ-scans. For oxygen partial pressures above 3 × 10−4 mbar and Tg < 540 °C, the formation of mixed (10.0) α-Ga2O3 and spinel-defective (110)-γ-Ga2O3 manifesting as defective inclusions was observed independent of the layer thickness d. A corresponding p(O2) − d − T phase diagram for the growth of Ga2O3 on m-plane sapphire by PLD is provided.
Stress relaxation of AlGaN on nonpolar m-plane GaN substrate
Authors: Lin Yingying , Sena Hadi , Frentrup Martin , Pristovsek Markus , Honda Yoshio , Amano Hiroshi
Published: June 2023

The stress relaxation with increasing thickness of metal-organic vapor phase epitaxy grown Al0.19Ga0.81N on quasi-bulk (101¯0) m-plane GaN substrates was investigated by x-ray diffraction. The anisotropic in-plane stress leads to an orthorhombic distortion of the lattice, which requires special mathematical treatment. Extending earlier works, we developed a method to calculate the distortion along [12¯10], [0001], and [101¯0] and obtained the lattice parameters, Al content, and strain values. The stress relaxation along the two in-plane directions involves two different mechanisms. First, the stress along [12¯10] relaxes by the onset of misfit dislocations through the {101¯0}⟨12¯10⟩ slip system while for thicker layers the stress along [0001] relaxes by crack formation. Comparing the cathodoluminescence emission at room temperature with the expected bandgap showed that both tensile in-plane strains along [12¯10] and [0001] decrease the bandgap.
Multichannel valley topological beam splitter based on different types of domain walls
Authors: Ma Jiajun , Ouyang Chunmei , Yang Yuting , Li Hongyi , Niu Li , Qian Xinyue , Liu Yi , Yang Bin , Xu Quan , Li Yanfeng , Liu Liyuan , Tian Zhen , Gu Jianqiang , Han Jiaguang , Zhang Weili
Published: June 2023

Topological photonics has made great progress from physical concept verification to new technical applications, and valley topological photonic crystal (TPCs) are one of the most important candidates for future applications in functional devices because of large bandwidth and lossless optical transport. However, due to the limitations of the design method and structure arrangement, the multichannel valley topological beam splitter (BS) has not yet been much explored. Here, we reveal the different robustness of four types of domain walls in valley TPCs. Benefiting from the differences in domain walls, we numerically present and experimentally demonstrate a highly integrated multichannel valley topological BS in the microwave regime. Compared with traditional BSs, it has the advantages of being more robust and compact and having more output ports and higher integration. The reported multichannel topological BS opens an avenue to engineer the flow of light and offers effective design approaches for integrated photonic device miniaturization.
The nucleation, growth, and adhesion of water bridges in sliding nano-contacts
Authors: Cassin Felix , Hahury Rachid , Lançon Thibault , Franklin Steve , Weber Bart
Published: June 2023

We provide experimental observations of the nucleation and growth of water capillary bridges in nanometer gaps between a laterally moving atomic force microscope probe and a smooth silicon wafer. We find rising nucleation rates with increasing lateral velocity and a smaller separation gap. The interplay between nucleation rate and lateral velocity is attributed to the entrainment of water molecules into the gap by the combination of lateral motion and collisions of the water molecules with the surfaces of the interface. The capillary volume of the full-grown water bridge increases with the distance between the two surfaces and can be limited by lateral shearing at high velocities. Our experimental results demonstrate a novel method to study in situ how water diffusion and transport impact dynamic interfaces at the nanoscale, ultimately leading to friction and adhesion forces at the macroscale.
A superconducting synapse exhibiting spike-timing dependent plasticity
Authors: Segall K. , Purmessur C. , D'Addario A. , Schult D.
Published: June 2023

The recent success of artificial intelligence (AI) systems has been accompanied by a rapid increase in the computational resources needed to successfully train them. This rate of increase threatens the future development of AI systems as they are presently configured. Unsupervised learning, where systems are trained online instead of through offline computation, offers a possible way forward. Here, we present the design of a synaptic circuit made from superconducting electronics capable of spike-timing dependent plasticity (STDP), a form of unsupervised learning. The synapse is constructed from three sub-circuits, each responsible for a part of the synaptic action. We demonstrate the operation of the synapse through numerical simulation and show that it reproduces the hallmark behaviors of STDP. Combined with existing superconducting neuromorphic components like neurons and axons, this synaptic structure could help form a fast, powerful, and energy-efficient Spiking Neural Network.
Experimental characterization of an asymmetric valveless pump based on soft robotics technology
Authors: Anatol J. , García-Díaz M. , Barrios-Collado C. , Moneo-Fernández J. A. , Castro-Ruiz F. , Sierra-Pallares J.
Published: June 2023

Asymmetric pumping can be achieved by periodically compressing a flexible tube in its plane of symmetry using an actuator, as long as the rigid pipes connected to its ends are asymmetric. This mechanism, together with impedance pumping, composes the Liebau effect. While there have been numerous studies on impedance pumping, there is a lack of available research on asymmetric pumping. The aim of this study is to examine the influence of key parameters on the performance of this type of pump. In addition, this study implements an actuator based on soft robotics technology in asymmetric valveless pumping for the first time. The pump developed in this study can be applied in different areas involving the pumping of special fluids, including biomedical applications.
Nonlinear optical response of polycrystalline GeSe films
Authors: Chen Weimin , Xiang Wenbin , Bai Chunzheng , Zhu Baohua , Gu Bing , Lv Changgui , Zhang Jiayu
Published: June 2023

GeSe exhibits in-plane optical anisotropy similar to black phosphorus and other two-dimensional materials, so it is believed to have remarkable nonlinear optical (NLO) properties. In this work, amorphous GeSe films were prepared by vacuum thermal evaporation. After annealing at 450 °C, GeSe films exhibited a polycrystalline phase. The NLO properties of these GeSe films were investigated by the Z-scan technique. The results indicated that GeSe films exhibited typical reverse saturable absorption (RSA) and self-focusing phenomenon. It was also found that the nonlinear optical parameters and laser-induced damage threshold of annealed recrystallized GeSe films were significantly improved. The nonlinear absorption and refractive coefficients were β = (2.90 ± 0.06)×10−7 m/W and n2= (1.06 ± 0.07)×10−13 m2/W at the incident laser intensity of 0.4 GW/cm2, respectively. The polycrystalline GeSe film showed remarkable RSA-induced optical limiting properties, which exhibited an optical limiting starting threshold of 0.018 GW/cm2 and an optical limiting threshold of 0.98 GW/cm2. These results strongly indicate that GeSe films have potential applications in solid-state optical limiting devices and laser protection.
Impact of simplicial complexes on epidemic spreading in partially mapping activity-driven multiplex networks
Authors: Zhang Shuofan , Zhao Dawei , Xia Chengyi , Tanimoto Jun
Published: June 2023

Over the past decade, the coupled spread of information and epidemic on multiplex networks has become an active and interesting topic. Recently, it has been shown that stationary and pairwise interactions have limitations in describing inter-individual interactions , and thus, the introduction of higher-order representation is significant. To this end, we present a new two-layer activity-driven network epidemic model, which considers the partial mapping relationship among nodes across two layers and simultaneously introduces simplicial complexes into one layer, to investigate the effect of 2-simplex and inter-layer mapping rate on epidemic transmission. In this model, the top network, called the virtual information layer, characterizes information dissemination in online social networks, where information can be diffused through simplicial complexes and/or pairwise interactions. The bottom network, named as the physical contact layer, denotes the spread of infectious diseases in real-world social networks. It is noteworthy that the correspondence among nodes between two networks is not one-to-one but partial mapping. Then, a theoretical analysis using the microscopic Markov chain (MMC) method is performed to obtain the outbreak threshold of epidemics, and extensive Monte Carlo (MC) simulations are also carried out to validate the theoretical predictions. It is obviously shown that MMC method can be used to estimate the epidemic threshold; meanwhile, the inclusion of simplicial complexes in the virtual layer or introductory partial mapping relationship between layers can inhibit the spread of epidemics. Current results are conducive to understanding the coupling behaviors between epidemics and disease-related information.
Breaking bandgap limitation: Improved photosensitization in plasmonic-based CsPbBr3 photodetectors via hot-electron injection
Authors: Qiu Conghui , Zhang Hao , Tian Chengcai , Jin Xuan , Song Qianglin , Xu Liye , Ijaz Mohsin , Blaikie Richard J. , Xu Qingyu
Published: June 2023

A higher detection performance and stability are always pursued in the development of photoelectric or photo-electrochemical devices, critical for their further commercial application. Here, we report a CsPbBr3-based photodetector engineered from a multilayer Si/Ag islands/CsPbBr3/PMMA system, showing an evidently enhanced photosensitization and breaking the absorption edge of CsPbBr3. On the one hand, the photocurrent contribution from plasmonic hot-electron injection effectively extends the detection limit of our photodetectors much below the band edge of CsPbBr3, depending only on Schottky barrier. On the other hand, the surface plasmons on nanoscale silver islands can considerably improve the light harvesting ability of the CsPbBr3 layer, ascribed to the confinement of light in the adjacency of silver islands. Numerical simulations show the localized enhancement of light near silver islands, corresponding to the excitation of localized surface plasmon resonances. It shows a higher light intensity distribution inside the CsPbBr3 layer of the photodetector consisting of Si/Ag islands/CsPbBr3/PMMA with the photodetector with only Ag islands in accordance with their current–voltage(I–V) characteristics. Ultimately, our plasmonic CsPbBr3-based photodetector presents a >10-fold increase in the photocurrent and a doubling of the operating lifetime. Our work provides important insight into the realization of the performance and stability of optoelectronic devices based on plasmonics.
Numerical investigation of airborne infection risk in an elevator cabin under different ventilation designs
Authors: Nazari Ata , Taghizadeh-Hesary Farzad
Published: June 2023

Airborne transmission of SARS-CoV-2 via virus-laden aerosols in enclosed spaces poses a significant concern. Elevators, commonly utilized enclosed spaces in modern tall buildings, present a challenge as the impact of varying heating, ventilation, and air conditioning (HVAC) systems on virus transmission within these cabins remains unclear. In this study, we employ computational modeling to examine aerosol transmission within an elevator cabin outfitted with diverse HVAC systems. Using a transport equation, we model aerosol concentration and assess infection risk distribution across passengers' breathing zones. We calculate the particle removal efficiency for each HVAC design and introduce a suppression effect criterion to evaluate the effectiveness of the HVAC systems. Our findings reveal that mixing ventilation, featuring both inlet and outlet at the ceiling, proves most efficient in reducing particle spread, achieving a maximum removal efficiency of 79.40% during the exposure time. Conversely, the stratum ventilation model attains a mere removal efficiency of 3.97%. These results underscore the importance of careful HVAC system selection in mitigating the risk of SARS-CoV-2 transmission within elevator cabins.
Numerical study of head-on collision of two equal-sized compound droplets
Authors: Ho Nang X. , Vu Truong V.
Published: June 2023

Although on-axis collisions between compound droplets are involved in numerous technological applications, no detailed investigation of such collisions is yet available. To address this problem, the present work uses an axisymmetric front-tracking method to numerically explore the dynamics of on-axis collisions of compound droplets that contain one or more inner droplets. Two identical droplets are placed symmetrically on the midplane of a computational domain and made to make contact with an initial colliding velocity. Various parameters such as the Reynolds number Re, the Weber number We, the size of the inner droplets, the interfacial tension ratio, and the eccentricity are considered. Three primary outcomes are observed: complete coalescence (CC), outer coalescence (OC), and rebound (R) for Re = 4–256 and We = 1–128. CC is when both the inner and outer droplets coalesce, whereas OC is when only the outer droplets coalesce. R is when the droplets come into contact and then bounce back. Increasing Re or decreasing We enhances the CC pattern, as does increasing the size of the inner droplets or the interfacial tension ratio. The influence of the initial distance between the droplets is also investigated. Finally, regime diagrams related to these patterns of collision are also presented.
Method for determining the electronegativity of bound atoms of chemical elements with a small atomic number
Authors: Mikhailov Igor F. , Mikhailov Anton I.
Published: June 2023

The classical approach of James and Brindley for determining the shielding of a nucleus by electrons from the atomic form factor of the scattering of x rays is generalized for atoms in a bound state. It is shown that for chemical elements with atomic number Z < 10, the ratio of the peaks of coherent IR and incoherent IC scattering in the range of (sin θ)/λ from 0.7 to 2.0 Å−1 is determined by the form factor of scattering by internal electrons of the (1, 0) level. For each atom in a multicomponent system, there is only one adjustable parameter—the effective charge Z* = (Z − s), which characterizes the shielding of the nucleus by electrons. Fitting the dependence IR/IC ((sin θ)/λ) allows you to determine Z* for each free or bound atom and calculate its electronegativity. The values of the electronegativity of lithium, boron, carbon, oxygen, and fluorine in compounds with different types of chemical bonds are analyzed.
Differential quartz-enhanced photoacoustic spectroscopy
Authors: Zhang Chu , Qiao Shunda , He Ying , Zhou Sheng , Qi Lei , Ma Yufei
Published: June 2023

In this paper, a differential quartz-enhanced photoacoustic spectroscopy (D-QEPAS) sensor is reported. The differential photoacoustic cell (PAC) was used to generate the photoacoustic effect. Two quartz tuning forks (QTFs) with a quality factor (Q) up to 10 000 were used as the acoustic wave transducers. The signal of D-QEPAS sensor was doubly enhanced by the differential characteristic of differential PAC and resonant response of QTF. The background noise was suppressed based on the differential principle. With the help of the finite element method, the acoustic field characteristics were simulated and calculated. Wavelength modulation spectroscopy technique and second harmonic (2f) detection technique were applied to detect photoacoustic signal. Trace acetylene (C2H2) gas detection was performed to verify the D-QEPAS sensor performance. The 2f signal amplitude of differential mode was 116.03 μV, which had a 1.65 times improvement compared with the 2f signal amplitudes of QTF1. When the integration time was 334 s, the minimum detection limit of D-QEPAS sensor was about 496.7 ppb. The reported D-QEPAS provides a development and idea for the widely reported QEPAS technique.
Optimized collision-specific parameters for binary mixtures of nitrogen, oxygen, argon, and helium
Authors: Hong Andrew Y. K. , Gallis Michael A.
Published: June 2023

Recently proposed collision-specific parameters for direct simulation Monte Carlo simulations are tested for binary mixtures of nitrogen, oxygen, and argon. Near ambient conditions, the traditional collision-averaged parameters are highly accurate, whereas the collision-specific parameters are not. The simulated transport using the collision-averaged parameters for mixtures with helium, however, is found to be inaccurate. Hence, we propose a novel method to determine molecular parameters by combining the Chapman–Enskog theory with empirical mixing rules and experimental data. The optimized parameters are highly accurate for the binary mixtures of nitrogen, oxygen, and argon and greatly improve the simulated transport for the helium mixtures.
GHRH agonist MR-409 protects β-cells from streptozotocin-induced diabetes
Authors: Louzada Ruy A. , Blandino-Rosano Manuel , Flores Sebastian , Lubaczeuski Camila , Cui Tengjiao , Sha Wei , Cai Renzhi , Schally Andrew V. , Bernal-Mizrachi Ernesto
Published: June 2023

Patients with type 1 diabetes (T1D) suffer from insufficient functional β-cell mass, which results from infiltration of inflammatory cells and cytokine-mediated β-cell death. Previous studies demonstrated the beneficial effects of agonists of growth hormone-releasing hormone receptor (GHRH-R), such as MR-409 on preconditioning of islets in a transplantation model. However, the therapeutic potential and protective mechanisms of GHRH-R agonists on models of T1D diabetes have not been explored. Using in vitro and in vivo models of T1D, we assessed the protective propertie of the GHRH agonist, MR409 on β-cells. The treatment of insulinoma cell lines and rodent and human islets with MR-409 induces Akt signaling by induction of insulin receptor substrate 2 (IRS2), a master regulator of survival and growth in β-cells, in a PKA-dependent manner. The increase in cAMP/PKA/CREB/IRS2 axis by MR409 was associated with decrease in β-cell death and improved insulin secretory function in mouse and human islets exposed to proinflammatory cytokines. The assessment of the effects of GHRH agonist MR-409 in a model of T1D induced by low-dose streptozotocin showed that mice treated with MR-409 exhibited better glucose homeostasis, higher insulin levels, and preservation of β-cell mass. Increased IRS2 expression in β-cells in the group treated with MR-409 corroborated the in vitro data and provided evidence for the underlying mechanism responsible for beneficial effects of MR-409 in vivo. Collectively, our data show that MR-409 is a novel therapeutic agent for the prevention and treatment of β-cells death in T1D.
A unified model for the dynamics of ATP-independent ultrafast contraction
Authors: Floyd Carlos , Molines Arthur T. , Lei Xiangting , Honts Jerry E. , Chang Fred , Elting Mary Williard , Vaikuntanathan Suriyanarayanan , Dinner Aaron R. , Bhamla M. Saad
Published: June 2023

In nature, several ciliated protists possess the remarkable ability to execute ultrafast motions using protein assemblies called myonemes, which contract in response to Ca
2+
ions. Existing theories, such as actomyosin contractility and macroscopic biomechanical latches, do not adequately describe these systems, necessitating development of models to understand their mechanisms. In this study, we image and quantitatively analyze the contractile kinematics observed in two ciliated protists (
Vorticella
sp. and
Spirostomum
sp.), and, based on the mechanochemistry of these organisms, we propose a minimal mathematical model that reproduces our observations as well as those published previously. Analyzing the model reveals three distinct dynamic regimes, differentiated by the rate of chemical driving and the importance of inertia. We characterize their unique scaling behaviors and kinematic signatures. Besides providing insights into Ca
2+
-powered myoneme contraction in protists, our work may also inform the rational design of ultrafast bioengineered systems such as active synthetic cells.
Phase separation of intrinsically disordered FG-Nups is driven by highly dynamic FG motifs
Authors: Dekker Maurice , Van der Giessen Erik , Onck Patrick R.
Published: June 2023

The intrinsically disordered FG-Nups in the central channel of the nuclear pore complex (NPC) form a selective permeability barrier, allowing small molecules to traverse by passive diffusion, while large molecules can only translocate with the help of nuclear transport receptors. The exact phase state of the permeability barrier remains elusive. In vitro experiments have shown that some FG-Nups can undergo phase separation into condensates that display NPC-like permeability barrier properties. Here, we use molecular dynamics simulations at amino acid resolution to study the phase separation characteristics of each of the disordered FG-Nups of the yeast NPC. We find that GLFG-Nups undergo phase separation and reveal that the FG motifs act as highly dynamic hydrophobic stickers that are essential for the formation of FG-Nup condensates featuring droplet-spanning percolated networks. Additionally, we study phase separation in an FG-Nup mixture that resembles the NPC stoichiometry and observe that an NPC condensate is formed containing multiple GLFG-Nups. We find that the phase separation of this NPC condensate is also driven by FG–FG interactions, similar to the homotypic FG-Nup condensates. Based on the observed phase separation behavior, the different FG-Nups of the yeast NPC can be divided into two classes: The FG-Nups (mostly GLFG-type) located in the central channel of the NPC form a highly dynamic percolated network formed by many short-lived FG–FG interactions, while the peripheral FG-Nups (mostly FxFG-type) at the entry and exit of the NPC channel likely form an entropic brush.