bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel colorimetric assay for sensitive detection of kanamycin based on the aptamer-regulated peroxidase-mimicking activity of Co3O4 nanoparticles
Authors: Zhou Xuan , Li Jiaxin , Hu Yuda , Wu Yaohui , Wang Yonghong , Ning Ge
Published: May 2023

We proposed, for the first time, a novel colorimetric assay for the sensitive detection of kanamycin based on the aptamer-regulated peroxidase-like activity of Co3O4 NPs.
One-step preparation of boronic acid-rich hydrothermal spheres for N-glycopeptide analysis from preeclampsia serum
Authors: Hua Shuwen , Wang Baichun , Wang Jiayi , He Bing , Ding Chuan-Fan , Wu Yongyao , Yan Yinghua , Xuan Rongrong
Published: May 2023

In this study, we developed a green, one-step hydrothermal carbonization (HTC) method that used water as the sole solvent to create boronic acid group-rich carbonaceous spheres (BCS).
Modulating tumor mechanics with nanomedicine for cancer therapy
Authors: Zhao Qingfu , Chen Jitang , Zhang Zhijie , Xiao Chen , Zeng Haowen , Xu Chen , Yang Xiangliang , Li Zifu
Published: May 2023

In this review, we discuss the nanomedicines that can regulate mechanical stiffness, solid stress, and IFP, with a focus on how nanomedicines change abnormal mechanical properties and facilitate drug delivery.
Nano-based ocular drug delivery systems: an insight into the preclinical/clinical studies and their potential in the treatment of posterior ocular diseases
Authors: Su Yun , Fan Xianqun , Pang Yan
Published: May 2023

A snapshot of nano-based drug delivery systems for ocular diseases in the preclinical/clinical studies and examples of novel nano-based eye drops for the treatment of posterior segment of the eye.
Advances in special wettable materials for adsorption separation of high-viscosity crude oil/water mixtures
Authors: Xiang Bin , Liu Qiuqiu , Yan Wenhao , Wei Yibin , Mu Peng , Li Jian
Published: May 2023

Separation and recovery strategies of high-viscosity crude oil through regulating surface wettability, designing pore structures and reducing crude oil viscosity.
Optical properties of in-plane chemically ordered i-MAX structures
Authors: Mokkath Junais Habeeb
Published: May 2023

DFT calculated optical reflectance of the i-MAX structure.
Understanding xenon and vacancy behavior in UO2, UN and U3Si2: a comparative DFT+Ustudy
Authors: Zhao Jiajun , Sun Dan , Xi Liu , Chen Ping , Zhao Jijun , Wang Yuanyuan
Published: May 2023

Charge density difference of a Xe atom at a U vacancy in UO2, UN and U3Si2.
Facile fabrication of an Au/Cu bimetallic nanocluster-based fluorescent composite film for sensitive and selective detection of Cr(vi)
Authors: Miao Xirui , Bai Jinna , Liang Yidan , Sun Menglei , Sun Yuanqing , Yang Xudong
Published: May 2023

We prepared a novel red fluorescence-emitting DPA-Au/Cu NCs@CS fluorescent composite film with great stability, selectivity, and sensitivity that can be utilized as a fluorescent probe to detect Cr(vi) in real time with a detection limit of 0.26 ppb.
A lignin-based membrane fabricated with a deep eutectic solvent
Authors: Gebreyohannes Abaynesh Yihdego , Aristizábal Sandra L. , Silva Liliana , Qasem Eyad A. , Chisca Stefan , Upadhyaya Lakshmeesha , Althobaiti Daniyah , Coutinho João A. P. , Nunes Suzana P.
Published: May 2023

Membrane technology is a sustainable process of molecular separation and purification in the chemical and pharmaceutical industries, with lower energy consumption than traditional thermal methods.
Ultra-fast, sensitive and low-cost real-time PCR system for nucleic acid detection
Authors: Huang Shaolei , An Yiquan , Xi Bangchao , Gong Xianglian , Chen Zhongfu , Shao Shan , Ge Shengxiang , Zhang Jun , Zhang Dongxu , Xia Ningshao
Published: May 2023

The system cleverly overshoots the target temperature to facilitate rapid heating and cooling and performs real-time PCR (45 cycles) with comparable sensitivity to commercial instrumentation in under 15 minutes.
Research and development ofN,N′-diarylureas as anti-tumor agents
Authors: Sun Xueyan , Xie Zhizhong , Lei Xiaoyong , Huang Sheng , Tang Guotao , Wang Zhe
Published: May 2023

Tumor neovascularization provides abundant nutrients for the occurrence and development of tumors, and is also an important factor in tumor invasion and metastasis, which has attracted extensive attention in anti-tumor therapy.
Photoinduced tandem radical cyclization/heteroarylation of N-allylbromodifluoroacetamides with quinoxalin-2(1H)-ones or coumarins under metal- and photocatalyst-free conditions
Authors: Zhao Wei , Xuan Liangming , Liu Yang , Yin Jiayi , Wang Haifeng , Yan Qiongjiao , Wang Wei , Huang Jin , Chen Fener
Published: May 2023

A photocatalyst-free visible-light-promoted tandem intramolecular cyclization/heteroarylation between bromodifluoroacetamides and quinoxalin-2(1H)-ones or coumarins was developed. The process could generate a broad range of α,α-difluoro-γ-lactams.
Inverse and distorted Co2SnO4 cubic spinel thin films for dimethylamine detection at room temperature
Authors: Nallakumar Santhosh , Thirumalaisamy Logu , Madhanagurusamy Sridharan , Kalainathan Sivaperuman , Usha Rani Muthurakku
Published: May 2023

To sense hazardous dimethylamine (DMA) gas, an ordered inverse spinel cobalt tin oxide (Co2SnO4) film was prepared and it showed a high response of 193.53 ± 2.7 at 100 ppm at room temperature, which makes Co2SnO4 films a good sensor for the DMA gas.
Spin crossover in Hofmann-like coordination polymers. Effect of the axial ligand substituent and its position
Authors: Avila Y. , Pérez O. , Sánchez L. , Vázquez M. C. , Mojica R. , González M. , Ávila M. , Rodríguez-Hernández J. , Reguera E.
Published: May 2023

Thermally induced spin crossover in the Fe(3-hydroxypyridine)2[M(CN)4] series with M = Ni, Pd, and Pt is reported. The role of the distortion of the iron atom coordination environment in the possibility of observing the spin crossover is explored.
Carbon nanotubes modified conductive ink for application to paper-based electrochemical biosensors for pathogenic DNA detection
Authors: Gupta Niharika , Kumar D. , Das Asmita , Sood Seema , Malhotra Bansi D.
Published: May 2023

Multiwalled carbon nanotubes modified conductive ink for paper-based gonorrheal diagnostic device.
Thiazolo[5,4-d]thiazoles with a spirobifluorene moiety as novel D–π–A type organic hosts: design, synthesis, structure–property relationship and applications in electroluminescent devices
Authors: Eckstein-Andicsová Anita , Tokárová Zita , Kozma Erika , Balogh Róbert , Vykydalová Anna , Mróz Wojciech , Tokár Kamil
Published: May 2023

Novel D–π–A type organic small-molecules with thiazolo[5,4-d]thiazole and spirobifluorene units. Optoelectronical properties suggests their applications in materials. Electroluminescent devices containing the novel TzTz-based derivatives 4b, 5b show affinitive emission.
Blue light-induced iniferter RAFT polymerization in aqueous-alcoholic media as a universal tool for the homopolymerization of various monomer families: kinetic investigations on different scales
Authors: Hub Lara , Koll Joachim , Radjabian Maryam , Abetz Volker
Published: May 2023

Influence of batch dimensions and blue light intensity on the kinetics of the photo-iniferter RAFT polymerization of four different monomers is investigated.
Efficient detection of polymeric mechanoradicalsviafluorescent molecular probes stabilized by steric hindrance
Authors: Yamamoto Takumi , Otsuka Hideyuki
Published: May 2023

Experimental investigation and buried volume analysis disclose that the introduction of bulky substituents to diarylacetonitrile derivatives improve the mechanoradical-detection ability.
Strategies for addressing the challenges of aqueous zinc batteries enabled by functional separators
Authors: Hao Zhendong , Dai Yuming , Xu Xiaolong , Zhao Xiuxiu , Cong Yuan , Wu Xiaoming , Zhou Weiqiang
Published: May 2023

This study summarizes the recent advances of functional separators for stable aqueous zinc batteries.
The Effelsberg survey of FU Orionis and EX Lupi objects
Authors: Szabó Zs. M. , Gong Y. , Yang W. , Menten K. M. , Bayandina O. S. , Cyganowski C. J. , Kóspál Á. , Ábrahám P. , Belloche A. , Wyrowski F.
Published: May 2023

Context. FU Orionis (FUor) and EX Lupi (EXor) type objects are two groups of peculiar and rare pre-main sequence low-mass stars that are undergoing powerful accretion outbursts during their early stellar evolution. Although water masers are widespread in star-forming regions and serve as powerful probes of mass accretion and ejection on small scales, little is known about the prevalence of water masers toward FUors and EXors.

Aims. We aim to perform the first systematic search for the 22.2 GHz water maser line in FUors and EXors in order to determine its overall incidence in these eruptive variables and to facilitate high angular-resolution follow-up observations.

Methods. We used the Effelsberg 100-m radio telescope to observe the H2O (616 – 523) transition at 22.2GHz toward a sample of 51 eruptive young stellar objects.

Results. We detected a total of five water masers in our survey; three are associated with eruptive stars, equivalent to a detection rate of ~6% for our sample of eruptive sources. These detections include one EXor, V512 Per (also known as SVS 13 or SVS 13A), and two FUors, Z CMa, and HH 354 IRS. This is the first reported detection of water maser emission towards HH 354 IRS. We also detected water maser emission in our pointing towards the FUor binary RNO 1B/1C, which most likely originates from the nearby deeply embedded source IRAS 00338+6312 (~4″ from RNO 1B/1C). Emission was also detected from H2O(B), (also known as SVS 13C), a Class 0 source ~30″ from the EXor V512 Per. The peak flux density of H2O(B) in our observations, 498.7 Jy, is the highest observed to date, indicating that we have serendipitously detected a water maser flare in this source. In addition to the two non-eruptive Class 0 sources (IRAS 00338+6312 and H2O(B)/SVS 13C), we detected maser emission towards one Class 0/I (HH 354 IRS) and two Class I (V512 Per/SVS 13A and Z CMa) eruptive stars.

Conclusions. Despite the low detection rate, we demonstrate the presence of 22.2 GHz water maser emission in both FUor and EXor systems, paving the way to radio interferometric observations to study the environments of these eruptive stars on small scales. Comparisons of our data with historical observations spanning several decades suggest that multiple water maser flares have occurred in both V512 Per and H2O(B).
Self-gravity in thin-disc simulations of protoplanetary discs: The smoothing length rectified and generalised to bi-fluids
Authors: Rendon Restrepo S. , Barge P.
Published: May 2023

Context. To mimic the evolution of protoplanetary discs (PPDs), 2D simulations that incorporate self-gravity must introduce a softening prescription of the gravitational potential. When the disc is only composed of gas, the smoothing length is proportional to the scale height of the gas. On the other hand, when a dust component is included, the question arises as to whether the smoothing length approach can still be used to not only quantify the dust self-gravity, but its gravitational interaction with gas as well.

Aims. We identified grey areas in the standard smoothing length formalism for computing self-gravity in PPDs entirely made up of gas. Our goal is to revisit the smoothing length approach, which can then be generalised to two phases, whereby the dust component may be considered as a pressureless fluid.

Methods. We used analytical developments to approximate the vertically averaged self-gravity when the smoothing length is not assumed to be constant, but by taking a spatial function instead.

Results. We obtained an analytical expression for the space-varying smoothing length, which strongly improves the accuracy of the self-gravity computation. For the first time, this method is generalised to address bi-fluid interactions in a PPD: two additional smoothing lengths are proposed for featuring an isolated dusty disc and gas-dust self-gravity interactions. On computational grounds, we prescribe the use of tapering functions for the purpose of avoiding numerical divergences. We also checked that our method continues to be compatible with standard fast Fourier transform algorithms and evaluated computational costs.

Conclusions. Our space-varying smoothing length allows us to: (i) solve the contradictions inherent in the constant smoothing length hypothesis; (ii) fit the 3D vertically averaged self-gravity with a high level of accuracy; and (iii) render it applicable to a bi-fluid description of PPDs with the use of two additional smoothing lengths. Such results are crucial to enable realistic 2D numerical simulations that account for self-gravity and are essential to improving our understanding of planetesimal formation and type I migration.
Chirped gap solitons in fiber Bragg gratings with polynomial law of nonlinear refractive index
Authors: Al-Ghafri Khalil S. , Sankar Mani , Krishnan Edamana V. , Khan Salam , Biswas Anjan
Published: May 2023

The objective of the present study is to examine the behaviors of chirped optical solitons in fiber Bragg gratings (BGs) with dispersive reflectivity. The form of nonlinear refractive index represents polynomial law nonlinearity. By virtue of phase-matching condition, the discussed model of coupled nonlinear Schrödinger equation is reduced to an integrable form. Consequently, chirped optical solitons having various profiles such as W-shaped, bright, dark, kink and anti-kink solitons are derived. Further to this, the chirp associated with these soliton structures are extracted. The impact of dispersive reflectivity, self-phase modulation and cross-phase modulation on the pulse propagation is investigated and it is induced that the changes of self-phase modulation and cross-phase modulation cause a marked rise in soliton amplitude which is subject to minor variations by dispersive reflectivity. The physical evolutions of chirped optical solitons are described along with the corresponding chirp to pave the way for possible applications in the field of fiber BGs.
Highly Efficient Synthesis of 3,3-Disubstituted Oxindoles through Direct Oxidative Alkylarylation of N-Arylacrylamides with Simple Alkanes
Authors: Chen Yan , Song Weihong , Han Xiaoyu , Zhou Zhixiang , Zhang Ziye , Liu Kai , Zeng Xiaofei
Published: May 2023

A direct oxidative alkylarylation reaction of N-arylacrylamides with simple alkanes for the synthesis of 3,3-disubstituted oxindoles under metal-free conditions was demonstrated. By using PhI(OAc)2 [(diacetoxy)iodobenzene] as an oxidant, a series of 3,3-disubstituted oxindoles bearing different aryl or alkyl substituents were generated in moderate to excellent chemical yields via a radical-initiated alkylation/cyclization process. The reported method features good functional group tolerance and wide substrate range, and provides an effective method for the preparation of various alkyl substituted 3,3-disubstituted oxindoles.
Self-intersection local time derivative for systems of non-linear stochastic heat equations
Authors: Yu Qian
Published: May 2023

We consider the existence and Hölder continuity conditions for the higher-order derivative of self-intersection local time for u(t, x), where u(t,x)=u1(t,x),…,ud(t,x) is the solution to a system of non-linear stochastic heat equations driven by a d-dimensional space-time white noise. Moreover, we study the cases of intersection local time and collision local time.
Heat capacity of microgram oxide samples by fast scanning calorimetry
Authors: Bonatti L. , Brugman B. L. , Subramani T. , Leinenweber K. D. , Navrotsky A.
Published: May 2023

Quantitative scanning calorimetry on microgram-sized samples opens a broad, new range of opportunities for studying the thermodynamic properties of quantity-limited materials, including those produced under extreme conditions or found as rare accessory minerals in nature. We calibrated the Mettler Toledo Flash DSC 2+ calorimeter to obtain quantitative heat capacities in the range 200–350 °C, using samples weighing between 2 and 11.5 μg. Our technique is applied to a new set of oxide materials to which it has never been used before, without the need for melting, glass transitions, or phase transformations. Heat capacity data were obtained for silica in the high pressure stishovite (rutile) structure, dense post-stishovite glass, standard fused quartz, and for TiO2 rutile. These heat capacities agree within 5%–15% with the literature values reported for rutile, stishovite, and fused SiO2 glass. The heat capacity of post-stishovite glass, made by heating stishovite to 1000 °C, is a newly reported value. After accurate calibrations, measured heat capacities were then used to calculate masses for samples in the microgram range, a substantial improvement over measurement in conventional microbalances, which have uncertainties approaching 50%–100% for such small samples. Since the typical uncertainty of heat capacities measured on 10–100 mg samples in conventional differential scanning calorimetry is typically 7% (1%–5% with careful work), flash differential scanning calorimetry, using samples a factor of 1000 smaller, increases the uncertainty of heat capacity measurements by a factor of <3, opening the door for meaningful measurements on ultra-small, high-pressure samples and other quantity-limited materials.
Study liquid–liquid phase separation with optical microscopy: A methodology review
Authors: Zhang Xiufeng , Li Haoyang , Ma Yue , Zhong Dongping , Hou Shangguo
Published: May 2023

Intracellular liquid–liquid phase separation (LLPS) is a critical process involving the dynamic association of biomolecules and the formation of non-membrane compartments, playing a vital role in regulating biomolecular interactions and organelle functions. A comprehensive understanding of cellular LLPS mechanisms at the molecular level is crucial, as many diseases are linked to LLPS, and insights gained can inform drug/gene delivery processes and aid in the diagnosis and treatment of associated diseases. Over the past few decades, numerous techniques have been employed to investigate the LLPS process. In this review, we concentrate on optical imaging methods applied to LLPS studies. We begin by introducing LLPS and its molecular mechanism, followed by a review of the optical imaging methods and fluorescent probes employed in LLPS research. Furthermore, we discuss potential future imaging tools applicable to the LLPS studies. This review aims to provide a reference for selecting appropriate optical imaging methods for LLPS investigations.
High-power laser beam in higher-order Hermite–Gaussian modes
Authors: Behren B. von , Heinze Joscha , Bode Nina , Willke Benno
Published: May 2023

The sensitivities of current gravitational-wave detectors are limited around signal frequencies of 100 Hz by mirror thermal noise. One proposed option to reduce this thermal noise is to operate the detectors in a higher-order spatial laser mode. This operation would require a high-power laser input beam in such a spatial mode. Here, we discuss the generation of the Hermite–Gaussian modes HG2,2, HG3,3, and HG4,4 using one water-cooled spatial light modulator (SLM) at a continuous-wave optical input power of up to 85 W. We report unprecedented conversion efficiencies for a single SLM of about 43%, 42%, and 41%, respectively, and demonstrate that the SLM operation is robust against the high laser power. This is an important step toward the implementation of higher-order laser modes in future gravitational-wave detectors.
Low-coherence interferometric measurement of the spatial frequency dependence of the light field backscattered by optical interfaces
Authors: Lequime M. , Khan I. , Bolliand A. , Zerrad M. , Amra C.
Published: May 2023

In this paper, we show how the combined use of low-coherence interferometry, balanced detection, and data processing comparable to that used in Fourier transform spectrometry allows us to characterize with ultimate resolutions (sub-parts per million in level, 0.2 nm in wavelength, and 25 mdeg in angle) the retro-reflection and retro-scattering response of both sides of a 2 mm thick silica wafer.
Enhanced solar hydrogen production by manipulating the spatial distribution of Pt catalyst onto Si micro-pyramid arrays
Authors: Wang Yuling , Chen Cong , Zhu Peng , Shen Junxia , Zou Shuai , Dong Wen , Su Xiaodong , Ni Weihai , Fan Ronglei , Shen Mingrong
Published: May 2023

Monolithic integrated photoelectrochemical devices consisting of semiconductors and co-catalysts have always been restricted by the trade-off between light absorption and catalytic activity upon frontside illumination. Herein, we proposed a facile strategy to spatio-selectively deposit Pt catalyst on the top of p-Si micro-pyramids, which not only enables substantial light absorption but also immensely boosts the charge transport and mass transfer. With the help of dark-field microscopy and microscopic photocurrent mapping, it is revealed that the top of p-Si micro-pyramids is an ideal electron-migration channel for efficient charge carrier extraction. This spatio-selective strategy affords the Si photocathode to achieve a high applied bias photon-to-current efficiency of 3.84% for hydrogen production, significantly greater than the control sample with the same amount of Pt catalyst deposited uniformly on the same substrates (0.04%).
Lightweight and effective tensor sensitivity for atomistic neural networks
Authors: Chigaev Michael , Smith Justin S. , Anaya Steven , Nebgen Benjamin , Bettencourt Matthew , Barros Kipton , Lubbers Nicholas
Published: May 2023

Atomistic machine learning focuses on the creation of models that obey fundamental symmetries of atomistic configurations, such as permutation, translation, and rotation invariances. In many of these schemes, translation and rotation invariance are achieved by building on scalar invariants, e.g., distances between atom pairs. There is growing interest in molecular representations that work internally with higher rank rotational tensors, e.g., vector displacements between atoms, and tensor products thereof. Here, we present a framework for extending the Hierarchically Interacting Particle Neural Network (HIP-NN) with Tensor Sensitivity information (HIP-NN-TS) from each local atomic environment. Crucially, the method employs a weight tying strategy that allows direct incorporation of many-body information while adding very few model parameters. We show that HIP-NN-TS is more accurate than HIP-NN, with negligible increase in parameter count, for several datasets and network sizes. As the dataset becomes more complex, tensor sensitivities provide greater improvements to model accuracy. In particular, HIP-NN-TS achieves a record mean absolute error of 0.927 kcalmol for conformational energy variation on the challenging COMP6 benchmark, which includes a broad set of organic molecules. We also compare the computational performance of HIP-NN-TS to HIP-NN and other models in the literature.
Thermal dissipation induced by fast-moving edge dislocations
Authors: Xiong Qi-Lin , Shimada Takahiro , Kitamura Takayuki
Published: May 2023

Microscopic mechanics of thermal dissipation induced by fast-moving edge dislocations are crucial for a deeper understanding of the nature of plastic deformation. Herein, we study the thermal dissipation induced by a fast-moving edge dislocation and discuss the effect of non-Schmid stress on the thermal dissipation using molecular dynamics simulations that can quantitatively distinguish the thermal dissipation and stored energy part of the energy emitted from a moving dislocation. We show that, of the energy emitted by the fast-moving edge dislocation, no more than 5% is used to generate elastic distortion of the local atomic structure, especially at low-stress levels, and almost all the energy emitted by the moving dislocation is converted into thermal energy and dissipated. The thermal dissipation of the moving edge dislocation depends significantly on the non-Schmid stress, specifically, temperature rise decreases almost linearly as the non-Schmid stress normal to the slip plane increases, and the possible mechanism is disclosed.
Effect of a redox-mediating ligand shell on photocatalysis by CdS quantum dots
Authors: Dou Florence Y. , Harvey Samantha M. , Mason Konstantina G. , Homer Micaela K. , Gamelin Daniel R. , Cossairt Brandi M.
Published: May 2023

Semiconductor quantum dots (QDs) are efficient organic photoredox catalysts due to their high extinction coefficients and easily tunable band edge potentials. Despite the majority of the surface being covered by ligands, our understanding of the effect of the ligand shell on organic photocatalysis is limited to steric effects. We hypothesize that we can increase the activity of QD photocatalysts by designing a ligand shell with targeted electronic properties, namely, redox-mediating ligands. Herein, we functionalize our QDs with hole-mediating ferrocene (Fc) derivative ligands and perform a reaction where the slow step is hole transfer from QD to substrate. Surprisingly, we find that a hole-shuttling Fc inhibits catalysis, but confers much greater stability to the catalyst by preventing a build-up of destructive holes. We also find that dynamically bound Fc ligands can promote catalysis by surface exchange and creation of a more permeable ligand shell. Finally, we find that trapping the electron on a ligand dramatically increases the rate of reaction. These results have major implications for understanding the rate-limiting processes for charge transfer from QDs and the role of the ligand shell in modulating it.
Scanning tunneling microscopy and spectroscopy characterization of Nb films for quantum applications
Authors: Berti G. , Torres-Castanedo C. G. , Goronzy D. P. , Bedzyk M. J. , Hersam M. C. , Kopas C. , Marshall J. , Iavarone M.
Published: May 2023

Niobium thin films are key components of superconducting microwave resonators. Interest in these devices has increased dramatically because of their application in quantum systems. Despite tremendous effort to improve their performance, loss mechanisms are still not well understood. Nb/substrate and Nb/air interfaces are likely culprits in contributing to decoherence and ultimately limiting the performance of superconducting devices. Here, we investigate the Nb/substrate interface by studying the effect of hydrogen-passivated H:Si(111) substrates on the local superconducting properties of ∼40 nm thick Nb films compared to Nb films grown on typical Si(001) substrates. Specifically, low-temperature scanning tunneling microscopy and spectroscopy are employed to compare nanoscale material properties. The atomically flat monohydride H:Si(111) substrates are found to yield a smoother and less defective interface with the Nb film. Correspondingly, the Nb films grown on H:Si(111) substrates present more uniform superconducting properties and exhibit less quasiparticle broadening.
High comprehensive energy storage properties in (Sm, Ti) co-doped sodium niobate ceramics
Authors: Yang Letao , Qi Junlei , Yang Mingcong , Fu Jing , Liu Yiqian , Lan Shun , Yang Bingbing , Meng Fanqi , Ren Weibin , Zhang Xinyue , Cai Jinghan , Lin Yuan-Hua , Guo Jinming , Kong Xi , Nan Ce-Wen
Published: May 2023

Ceramic capacitors are ubiquitously used in high power and pulse power applications, but their low energy density, especially at high temperatures (>150 °C), limits their fields of application. One of the reasons is the low energy efficiency under high electric fields and/or at high temperatures. In this work, equimolar Sm3+ and Ti4+ cations were doped in NaNbO3 to increase relaxor characteristics and energy storage properties. The optimal recoverable energy density Wrec of 6.5 J/cm3 and energy efficiency η of 96% were attained in the ceramics with 10% (Sm, Ti) concentration (SmT10). Dense microstructure and low dielectric loss were attributed to the high energy storage performance. Impedance spectra analysis revealed that the grain boundary resistance dominates at low temperatures, while the grain resistance dominates at high temperatures. The ceramics show stable Wrec and η in a broad temperature range of −90 to 200 °C and repeated charge–discharge cycles up to 105. The comprehensive energy storage performance indicates SmT10 ceramics are among potential candidates for ceramic capacitors working at high temperatures.
Mutually magnetically insulated two-species Brillouin flow
Authors: Darr Adam Michael , Cartwright K. L.
Published: May 2023

In this work, we use the Brillouin flow analytic framework to examine the physics of Magnetically Insulated Transmission Lines (MITL). We derive a model applicable to any particle species, including both positive and negative ions, in planar and cylindrical configurations. We then show how to self-consistently solve for two-species simultaneously, using magnetically insulated electrons and positive ions as an example. We require both layers to be spatially separated and magnetically insulated (mutually magnetically insulated); for a 7.5 cm gap with a 2 MV bias voltage, this condition requires magnetic fields in excess of 2.73 T. We see a close match between mutually insulated MITL performance and “superinsulated” (high degree of magnetic insulation) electron-only theory, as may be expected for these high magnetic fields. However, the presence of ions leads to several novel effects: (1) Opposite to electron-only theory, total electron currents increase rather than decrease as the degree of magnetic insulation becomes stronger. The common assumption of neglecting electrons for superinsulated MITL operation must be revisited when ions are present—we calculate up to 20× current enhancement. (2) The electron flow layer thickness increases up to double, due to ion space-charge enhancement. (3) The contributions from both ions and electrons to the MITL flow impedance are calculated. The flow impedance drops by over 50% when ions fill the gap, which can cause significant reflections at the load if not anticipated and degrade performance. Additional effects and results from the inclusion of the ion layer are discussed.
Demonstration of frequency stability limited by thermal fluctuation noise in silicon nitride nanomechanical resonators
Authors: St-Gelais Raphael
Published: May 2023

The frequency stability of nanomechanical resonators (NMRs) dictates the performance level of many state-of-the-art sensors (e.g., mass, force, temperature, radiation) that relate an external physical perturbation to a resonance frequency shift. While this is obviously of fundamental importance, accurate models and understandings of sources of frequency instability are not always available. The contribution of thermomechanical noise to frequency stability has been well studied in recent years and is often the fundamental performance limitation. Frequency stability limited by thermal fluctuation noise has attracted less interest but is nevertheless of fundamental importance notably in temperature sensing applications. In particular, temperature-sensitive NMR have become promising candidates for replacing traditional bolometers in infrared radiation sensing. However, reaching the ultimate detectivity limit of thermal radiation sensors requires their noise to be dominated by fundamental thermal fluctuation, which has not been demonstrated to date. In this work, we first develop a theoretical model for computing the frequency stability of NMR by considering the effect of both additive phase noise (i.e., thermomechanical and experimental detection noise) and thermal fluctuation noise in a close-loop frequency tracking scheme. We thereafter validate this model experimentally and observe thermal fluctuation noise in SiN drum resonators of various sizes at room temperature. Our work shows that by using resonators of specific characteristics—such as high temperature sensitivity, high mechanical quality factors, and high mass-to-thermal-conductance ratio—one can minimize additive phase noise below thermal fluctuation noise. This paves the way for uncooled NMR-based radiation sensors that can reach the fundamental detectivity limit of thermal radiation sensing and outperform existing technologies.
Theory of the ion–electron temperature relaxation rate in strongly magnetized plasmas
Authors: Jose Louis , Baalrud Scott D.
Published: May 2023

Recent works have shown that strongly magnetized plasmas characterized by having a gyrofrequency greater than the plasma frequency exhibit novel transport properties. One example is that the friction force on a test charge shifts, obtaining components perpendicular to its velocity in addition to the typical stopping power component antiparallel to its velocity. Here, we apply a recent generalization of the Boltzmann equation for strongly magnetized plasmas to calculate the ion–electron temperature relaxation rate. Strong magnetization is generally found to increase the temperature relaxation rate perpendicular to the magnetic field and to cause the temperatures parallel and perpendicular to the magnetic field to not relax at equal rates. This, in turn, causes a temperature anisotropy to develop during the equilibration. Strong magnetization also breaks the symmetry of independence of the sign of the charges of the interacting particles on the collision rate, commonly known as the “Barkas effect.” It is found that the combination of oppositely charged interaction and strong magnetization causes the ion–electron parallel temperature relaxation rate to be significantly suppressed, scaling inversely proportional to the magnetic field strength.
Strengths and limitations of the adiabatic exact-exchange kernel for total energy calculations
Authors: Hellgren Maria , Baguet Lucas
Published: May 2023

We investigate the adiabatic approximation to the exact-exchange kernel for calculating correlation energies within the adiabatic-connection fluctuation–dissipation framework of time-dependent density functional theory. A numerical study is performed on a set of systems having bonds of different character (H2 and N2 molecules, H-chain, H2-dimer, solid-Ar, and the H2O-dimer). We find that the adiabatic kernel can be sufficient in strongly bound covalent systems, yielding similar bond lengths and binding energies. However, for non-covalent systems, the adiabatic kernel introduces significant errors around equilibrium geometry, systematically overestimating the interaction energy. The origin of this behavior is investigated by studying a model dimer composed of one-dimensional, closed-shell atoms, interacting via soft-Coulomb potentials. The kernel is shown to exhibit a strong frequency dependence at small to intermediate atomic separation that affects both the low-energy spectrum and the exchange-correlation hole obtained from the corresponding diagonal of the two-particle density matrix.
Nonlinear resonant magnetoelectric effect in a circumferentially magnetized ferromagnetic–piezoelectric ring heterostructure
Authors: Savelev Dmitrii V. , Fedulov Fedor A. , Musatov Vladimir I. , Burdin Dmitri A. , Bolotina Ekaterina V. , Fetisov Leonid Y. , Fetisov Yuri K.
Published: May 2023

The nonlinear magnetoelectric (ME) effect of voltage harmonic generation in a ring heterostructure, comprising a magnetostrictive layer of an amorphous ferromagnet and a piezoelectric layer of lead zirconate titanate is investigated. The structure was circumferentially magnetized with a permanent field H = 0–40 Oe and excited by a circular alternating magnetic field h = 0–3.6 Oe. At the radial acoustic resonance frequency of the structure of ∼54.2 kHz, the first voltage harmonic generation efficiency was 2.9 V/(Oe cm), the second was 0.95 V/(Oe2 cm), and the third was 0.21 V/(Oe3 cm). The absence of demagnetization effects in the ring structure, in comparison with a planar one, leads to a decrease in the optimal biasing magnetic field as well as to a change in the dependence of the second and third ME voltage harmonics on the magnetic field. The discovered nonlinear effect can be used to create frequency doublers.
Log-law recovery through reinforcement-learning wall model for large eddy simulation
Authors: Vadrot Aurélien , Yang Xiang I. A. , Bae H. Jane , Abkar Mahdi
Published: May 2023

This paper focuses on the use of reinforcement learning (RL) as a machine-learning (ML) modeling tool for near-wall turbulence. RL has demonstrated its effectiveness in solving high-dimensional problems, especially in domains such as games. Despite its potential, RL is still not widely used for turbulence modeling and is primarily used for flow control and optimization purposes. A new RL wall model (WM) called VYBA23 is developed in this work, which uses agents dispersed in the flow near the wall. The model is trained on a single Reynolds number (Reτ=104) and does not rely on high-fidelity data, as the backpropagation process is based on a reward rather than an output error. The states of the RLWM, which are the representation of the environment by the agents, are normalized to remove dependence on the Reynolds number. The model is tested and compared to another RLWM (BK22) and to an equilibrium wall model, in a half-channel flow at eleven different Reynolds numbers {Reτ∈[180;1010]}. The effects of varying agents' parameters, such as actions range, time step, and spacing, are also studied. The results are promising, showing little effect on the average flow field but some effect on wall-shear stress fluctuations and velocity fluctuations. This work offers positive prospects for developing RLWMs that can recover physical laws and for extending this type of ML models to more complex flows in the future.
Discrete thermokinetic computational model of laser-induced phase transitions in phase-changing materials
Authors: Nevzorov A. A. , Mikhalevsky V. A. , Eliseev N. N. , Kiselev A. V. , Burtsev A. A. , Ionin V. V. , Khmelenin D. N. , Lotin A. A.
Published: May 2023

This paper presents a thermokinetic computational model of phase transitions in GST225 (germanium–antimony–tellurium) thin films [as well as other phase change materials (PCMs)] induced and initiated by the impact of nano- and femtosecond laser pulses in a wide energy fluence range according to the results of experimental studies using Raman spectra and thin-film samples of TEM cross-sectional image analysis. Applying this phase transition model makes it possible to understand the mechanism of the induced phase transition regarding the usage of PCMs in photonics and optoelectronic devices, which require precise control of the phase state of their PCM-based active elements for their functioning. The proposed model shows the internal structure of the sample, generating both the profile of the crystalline fraction distribution over the sample's depth, providing images of virtual TEM sections, as well as the volume distribution of the crystalline phase.
Large eddy simulation of flow in porous media: Analysis of the commutation error of the double-averaged equations
Authors: Sadowski W. , Sayyari M. , di Mare F. , Marschall H.
Published: May 2023

The continuum approach employing porous media models is a robust and efficient solution method in the area of the simulation of fixed-bed reactors. This paper applies the double-averaging methodology to refine the continuum approach, opening a way to alleviate its main limitations: space-invariant averaging volume and inaccurate treatment of the porous/fluid interface. The averaging operator is recast as a general space–time filter allowing for the analysis of commutation errors in a classic large eddy simulation (LES) formalism. An explicit filtering framework has been implemented to carry out an a posteriori evaluation of the unclosed terms appearing in the double-averaged Navier–Stokes (DANS) equations, also considering a space-varying filter width. Two resolved simulations have been performed. First, the flow around a single, stationary particle has been used to validate derived equations and the filtering procedure. Second, an LES of the turbulent flow in a channel partly occupied with a porous medium has been realized and filtered. The commutation error at the porous–fluid interface has been evaluated and compared to the prediction of two models. The significance of the commutation error terms is also discussed and assessed. Finally, the solver for DANS equations has been developed and used to simulate both of the studied geometries. The magnitude of the error associated with neglecting the commutation errors has been investigated, and an LES simulation combined with a porous drag model was performed. Very encouraging results have been obtained indicating that the inaccuracy of the drag closure overshadows the error related to the commutation of operators.
Shapes of floating droplets under non-uniform heating from below
Authors: Simanovskii Ilya , Nepomnyashchy Alexander , Viviani Antonio , Queeckers Patrick , Parente Alessandro
Published: May 2023

Floating droplets (liquid lenses) are widely used in engineering applications. A typical way of droplet manipulation is the non-uniform heating. In the present work, the influence of two-dimensional spatial inhomogeneity of temperature on the dynamics and instabilities of a droplet floating on a heated liquid substrate is investigated. The problem is studied numerically in the framework of the slender droplet approximation and the precursor model. It is shown that spatial temperature inhomogeneity leads to the liquid redistribution in the substrate toward the region of lower temperature, which is accompanied by the change in the droplet shape. Heating from below can lead to the substrate layer's rupture due to its monotonic instability. Symmetric and asymmetric droplets under the action of spatial temperature inhomogeneity have been obtained.
Asymmetric chiral coupling in a topological resonator
Authors: Shi Shushu , Xie Xin , Yan Sai , Yang Jingnan , Dang Jianchen , Xiao Shan , Yang Longlong , Dai Danjie , Fu Bowen , Yuan Yu , Zhu Rui , Su Xiangbin , Liu Hanqing , Zuo Zhanchun , Wang Can , Ni Haiqiao , Niu Zhichuan , Gong Qihuang , Xu Xiulai
Published: May 2023

Chiral light-matter interactions supported by topological edge modes at the interface of valley photonic crystals provide a robust method to implement the unidirectional spin transfer. The valley topological photonic crystals possess a pair of counterpropagating edge modes. The edge modes are robust against the sharp bend of 60° and 120°, which can form a resonator with whispering gallery modes. Here, we demonstrate the asymmetric emission of chiral coupling from single quantum dots in a topological resonator by tuning the coupling between a quantum emitter and a resonator mode. Under a magnetic field in Faraday configuration, the exciton state from a single quantum dot splits into two exciton spin states with opposite circularly polarized emissions due to the Zeeman effect. Two branches of the quantum dot emissions couple to a resonator mode in different degrees, resulting in an asymmetric chiral emission. Without the demanding of site-control of quantum emitters for chiral quantum optics, an extra degree of freedom to tune the chiral contrast with a topological resonator could be useful for the development of on-chip integrated photonic circuits.
Ultrafast low-jitter optical response in high-temperature superconducting microwires
Authors: Kumar A. , Panna D. , Bouscher S. , Koriat A. , Nitzav Y. , Jacovi R. , Kanigel A. , Hayat A.
Published: May 2023

We report ultrafast optical response in high-Tc superconductor (YBa2Cu3O7−δ) based microwires operating at 76 K and we find a rise time ∼850 ps and a fall time ∼1250 ps and an upper limit of timing jitter of ∼100 ps, using twice the standard deviation of the fitted data. In our experiment, incident power is proven to be an important factor for a device jitter. At low incident power, a lower rate of hot-spot generation by a smaller number of absorbed photons results in a longer latency time to obtain the required number of hot-spots for superconductor-to-normal transition. The lower hot-spot generation rate also results in larger timing jitter of the device. Whereas, at high incident power, a higher hot-spot generation rate yields shorter latency and smaller timing jitter. These observations agree well with our statistical model. Enhancing the sensitivity of the current device can enable future high-Tc superconductor nanowire single photon detectors, toward the widespread use of ultrafast quantum technologies.
Magnetic functionalization of ZnO nanoparticles surfaces via optically generated methyl radicals
Authors: Marin D. , Gerbaud G. , Margeat O. , Ziarelli F. , Ferrer F. , Ouari O. , Campos A. , Bertaina S. , Savoyant A.
Published: May 2023

The combination of nuclear and electron magnetic resonance techniques, in pulse and continuous wave regimes, is used to unravel the nature and features of the light-induced magnetic state arising at the surface of chemically prepared zinc oxide nanoparticles (NPs) occurring under 120 K when subjected to a sub-bandgap (405 nm) laser excitation. It is shown that the four-line structure observed around g ∼ 2.00 in the as-grown samples (beside the usual core-defect signal at g ∼ 1.96) arises from surface-located methyl radicals (•CH3), originating from the acetate capped ZnO molecules. By functionalizing the as-grown zinc oxide NPs with deuterated sodium acetate, the •CH3 electron paramagnetic resonance (EPR) signal is replaced by trideuteromethyl (•CD3). For •CH3, •CD3, and core-defect signals, an electron spin echo is detected below ∼100 K, allowing for the spin–lattice and spin–spin relaxation-time measurements for each of them. Advanced pulse-EPR techniques reveal the proton or deuteron spin-echo modulation for both radicals and give access to small unresolved superhyperfine couplings between adjacent •CH3. In addition, electron double resonance techniques show that some correlations exist between the different EPR transitions of •CH3. These correlations are discussed as possibly arising from cross-relaxation phenomena between different rotational states of radicals.
Assessment of microplastic accumulation in aquatic insects of different feeding guilds collected from wastewater in Sohag Governorate, Egypt
Authors: Khedre Azza M. , Ramadan Somaia A. , Ashry Ali , Alaraby Mohamed
Published: May 2023

Context Microplastic (MP) contamination is a strong candidate to be one of the most important environmental problems worldwide. Microplastics have been detected in many freshwater organisms because of increasing plastic contamination within aquatic ecosystems. However, the correlation between MPs in organisms and their surrounding environments still needs further study. Aim This is the first study assessing the accumulation of MPs in aquatic fauna from water and sediment by bioaccumulation equations in one of the wastewater basins in Sohag Governorate, Egypt. Methods Four common freshwater insect families representing different feeding guilds were employed to detect MP contamination. Key results The collector–gatherers (Chironomidae and Hydrophilidae) recorded the highest MP load per gram wet weight, the highest bioaccumulation factor (BCF), and the biota-sediment accumulation factor (BSAF), whereas predators (Aeshnidae) recorded the lowest values. In both sediment and water, polyester fibres were the most common type of MP, followed by fragments (polyethylene and polypropylene). However, only polyester fibres were found in the different insect taxa. The blue colour was the predominant colour in the water, sediment and insect fauna. The mean length of fibres in the different insects was a little smaller than those in the surrounding environment. Conclusion The present study suggests that MP ingestion by aquatic insects is not necessarily associated with environmental pollution levels, because other factors such as feeding strategies and habitats may play an important role in MP ingestion. Implications The presence of MPs in the insects (lower trophic levels) gives a possibility of inter trophic-level transfer through predation. As a result, higher trophic-level studies in different feeding groups should be conducted to detect the potential risk of MPs on different freshwater fauna.