bluuebunny/crossref_metadata_2025 huggingface dataset:
New physical insights into the supporting subspace factorization of XMS-CASPT2 and generalization to multiple spin states via spin-free formulation
Authors: Song Chenchen
Published: March 2024

This paper introduces a spin-free formulation of the supporting subspace factorization [C. Song and T. J. Martínez, J. Chem. Phys. 149, 044108 (2018)], enabling a reduction in the computational scaling of the extended multi-state complete active space second-order perturbation (XMS-CASPT2) method for arbitrary spins. Compared to the original formulation that is defined in the spin orbitals and is limited to singlet states, the spin-free formulation in this work treats different spin states equivalently, thus naturally generalizing the idea beyond singlet states. In addition, we will present a new way of deriving the supporting subspace factorization with the purpose of understanding its physical interpretation. In this new derivation, we separate the sources that make CASPT2 difficult into the “same-site interactions” and “inter-site interactions.” We will first show how the Kronecker sum can be used to remove the same-site interactions in the absence of inter-site interactions, leading to MP2 energy in dressed orbitals. We will then show how the inter-site interactions can be exactly recovered using Löwdin partition, where the supporting subspace concept will naturally arise. The new spin-free formulation maintains the main advantage of the supporting subspace factorization, i.e., allowing XMS-CASPT2 energies to be computed using highly optimized MP2 energy codes and Fock build codes, thus reducing the scaling of XMS-CASPT2 to the same scaling as MP2. We will present and discuss results that benchmark the accuracy and performance of the new method. To demonstrate how the new method can be useful in studying real photochemical systems, the supporting subspace XMS-CASPT2 is applied to a photoreaction sensitive to magnetic field effects. The new spin-free formulation makes it possible to calculate the doublet and quartet states required in this particular photoreaction mechanism.
Resonant exceptional points sensing in terahertz metasurfaces
Authors: Wang Lei , Liu Hang , Li Tong , Tian Da , Zhang Caihong , Wu Jingbo , Fan Kebin , Jin Biaobing , Chen Jian , Wu Peiheng
Published: March 2024

The phenomenon of simultaneous degeneracy of eigenvalues and eigenstates in non-Hermitian systems, known as exceptional points (EPs), renders systems in the vicinity of EP highly sensitive to perturbations in the environment. Recently, research works on terahertz metasurfaces primarily focused on finding the degenerate eigenvalue using the transmission matrix, known as the scattering EP, while neglecting exploration of another form of EP—the resonant EP. In this study, we numerically, theoretically, and experimentally investigate the resonant EP in terahertz metasurfaces, whose unit cell is composed of two unidentical length metal rods in a two-energy level non-Hermitian system. By altering two system parameters, we can manipulate the coupling between the two resonators, thereby directly realizing the singularity of complex frequency through only a single measurement. Furthermore, our simulations and measurements indicate a sensitivity of up to 9046 GHz/(RIU·mm), which underscores the high sensitivity characteristics of EP. Our approach not only contributes a fresh perspective on understanding EP in non-Hermitian terahertz metasurfaces but also proposes alternative methods for high-sensitivity terahertz sensing.
Frequency-locked measurement of floating potential fluctuations in cold micro-plasma jets: Interactive surface feedback effects on reactive species generation
Authors: Behmani Deepika , Keidar Michael , Bhattacharjee Sudeep
Published: March 2024

Frequency-locked measurements of floating potential fluctuations are carried out in a cold atmospheric pressure micro-plasma jet interacting with substrates of varying electrical permittivity (εr). The range of fluctuation frequencies (∼ 0.5–9 kHz) is compared with that determined from the time series of floating potential fluctuations and its fast Fourier transform. Results of these independent methods to determine the fluctuation frequencies are found to agree reasonably well, thereby affirming their existence in the micro-plasma jet. Substrate feedback effects dictated by εr are found to influence the amplitude of fluctuations and threshold breakdown voltage. The spectral emission line intensity corresponding to the reactive oxygen and nitrogen species, which is critical for biomedical applications, decrease drastically in the presence of stronger levels of fluctuations, indicating a bearing on their generation.
Extending the definition of atomic basis sets to atoms with fractional nuclear charge
Authors: Domenichini Giorgio
Published: March 2024

Alchemical transformations showed that perturbation theory can be applied also to changes in the atomic nuclear charges of a molecule. The alchemical path that connects two different chemical species involves the conceptualization of a non-physical system in which an atom possess a non-integer nuclear charge. A correct quantum mechanical treatment of these systems is limited by the fact that finite size atomic basis sets do not define exponents and contraction coefficients for fractional charge atoms. This paper proposes a solution to this problem and shows that a smooth interpolation of the atomic orbital coefficients and exponents across the periodic table is a convenient way to produce accurate alchemical predictions, even using small size basis sets.
Fractal and first-passage properties of a class of self-similar networks
Authors: Yuan Zhenhua , Peng Junhao , Gao Long , Shao Renxiang
Published: March 2024

A class of self-similar networks, obtained by recursively replacing each edge of the current network with a well-designed structure (generator) and known as edge-iteration networks, has garnered considerable attention owing to its role in presenting rich network models to mimic real objects with self-similar structures. The generator dominates the structural and dynamic properties of edge-iteration networks. However, the general relationships between these networks’ structural and dynamic properties and their generators remain unclear. We study the fractal and first-passage properties, such as the fractal dimension, walk dimension, resistance exponent, spectral dimension, and global mean first-passage time, which is the mean time for a walker, starting from a randomly selected node and reaching the fixed target node for the first time. We disclose the properties of the generators that dominate the fractal and first-passage properties of general edge-iteration networks. A clear relationship between the fractal and first-passage properties of the edge-iteration networks and the related properties of the generators are presented. The upper and lower bounds of these quantities are also discussed. Thus, networks can be customized to meet the requirements of fractal and dynamic properties by selecting an appropriate generator and tuning their structural parameters. The results obtained here shed light on the design and optimization of network structures.
Fully light-modulated memristor based on ZnO/MoOx heterojunction for neuromorphic computing
Authors: Zheng Jiahui , Du Yiming , Dong Yongjun , Shan Xuanyu , Tao Ye , Lin Ya , Zhao Xiaoning , Wang Zhongqiang , Xu Haiyang , Liu Yichun
Published: March 2024

Emerging optoelectronic memristors are promising candidates to develop neuromorphic computing, owing to the combined advantages of photonics and electronics. However, the reversible modulation on device conductance usually requires complicated operations involving hybrid optical/electrical signals. Herein, we design a fully light-modulated memristor based on ZnO/MoOx heterojunction, which exhibits potentiation and depression behaviors under the irradiation of ultraviolet and visible light, respectively. Several basic synaptic functions have been emulated by utilizing optical signals, including short-term/long-term plasticity and spike-number-dependent plasticity. Based on the all-optical modulation characteristics, low-level image pre-processing (including contrast enhancement and noise reduction) is demonstrated. Furthermore, logic operations (“AND,” “NOTq,” and “NIMP”) can be performed by combining various optical signals in the same device. The memristive switching mechanism under optical stimulus can be attributed to barrier change at the heterojunction interface. This work proposes a fully light-modulated memristor based on ZnO/MoOx heterojunction that may promote the development of neuromorphic computing with high efficiency.
A CASSCF/MRCI trajectory surface hopping simulation of the photochemical dynamics and the gas phase ultrafast electron diffraction patterns of cyclobutanone
Authors: Miao Xincheng , Diemer Kira , Mitrić Roland
Published: March 2024

We present the simulation of the photochemical dynamics of cyclobutanone induced by the excitation of the 3 s Rydberg state. For this purpose, we apply the complete active space self-consistent field method together with the spin–orbit multireference configuration interaction singles treatment, combined with the trajectory surface hopping for the inclusion of nonadiabatic effects. The simulations were performed in the spin-adiabatic representation, including nine electronic states derived from three singlet and two triplet spin-diabatic states. Our simulations reproduce the two previously observed primary dissociation channels: the C2 pathway yielding C2H4 + CH2CO and the C3 pathway producing c-C3H6 + CO. In addition, two secondary products, CH2 + CO from the C2 pathway and C3H6 from the C3 pathway, both of them previously reported, are also observed in our simulation. We determine the ratio of the C3:C2 products to be about 2.8. Our findings show that most of the trajectories reach their electronic ground state within 200 fs, with dissociation events finished after 300 fs. We also identify the minimum energy conical intersections that are responsible for the relaxation and provide an analysis of the photochemical reaction mechanism based on multidimensional scaling. Furthermore, we demonstrate a minimal impact of triplet states on the photodissociation mechanism within the observed timescale. In order to provide a direct link to experiments, we simulate the gas phase ultrafast electron diffraction patterns and connect their features to the underlying structural dynamics.
Above-77 K operation of charge sensitive infrared phototransistor with dynamically controlled optical gate
Authors: Xu Hongtao , Wang Hengliang , Zhang Lijian , Zhu Liping , Chen Pingping , Lu Wei , An Zhenghua
Published: March 2024

Charge sensitive infrared phototransistors (CSIPs) show great promise for sensitive mid-infrared photodetection, extending up to single-photon counting, owing to the built-in amplification mechanism. However, the operating temperature of previously reported CSIPs has been limited to below 30 K. In this work, we propose a technique that enhances the operating temperature to above liquid nitrogen temperature by dynamically controlling the electrostatic potential of the optical floating gate (FG). This control effectively suppresses the annihilation of photogenerated holes in the FG, mitigating the vertical recombination process of thermally excited electrons. We detected the photosignal up to ∼85 K under a photon flux of Φ∼3.6×108 s−1. An outstanding photoresponsivity (R=39.11 A/W) to external blinking light at the peak wavelength of λ=11μm is achieved at 77 K. Our work not only extends the practical application of CSIPs, meeting the high demand for high temperature operation, but also offers more flexibility in fabricating more general highly sensitive phototransistors.
Economic and low-carbon dispatch of industrial integrated energy system with EV load based on Stackelberg game framework
Authors: Chen Lingjie , Song Chunyue , Jiang Wei , Zhao Jun
Published: March 2024

Industrial integrated energy systems (IESs) and electric vehicles (EVs) provide new solutions for addressing the increasing challenges of the energy crisis and environmental pollution. With the increasing number of EVs and smart charging stations in industrial IES, the uncoordinated charging load of EVs imposes significant pressure on IES. Therefore, a well-designed dispatch scheme is crucial for reducing the economic cost for both parties, alleviating the energy supply pressure on IES, and promoting the development of a low-carbon society. To this end, given the load characteristics of EVs in industrial IES, we propose a dispatch framework based on the Stackelberg game theory, which includes the leader and the follower. The leader IES is responsible for formulating both unit dispatch and demand response plans, as well as determining the charging pricing for the smart charging station. The follower smart charging station optimizes EVs charging power by minimizing the charging cost in order to protect the interest of EV owners. Additionally, we introduce the carbon emission flow model into charging station pricing to shift the responsibility for carbon emissions from the generation side to the EV load side. Considering that the two-layer game model is difficult to solve, we use the Karush–Kuhn–Tucker condition and duality theorem to transform it into an equivalent single-layer optimization problem, which is easily solved. Simulation results demonstrate that the proposed game framework effectively reduces the economic cost of IES and the charging cost of EVs, alleviates the pressure from charging load, and reduces the carbon emissions of industrial IES.
A pipe arrangement structure triboelectric nanogenerator for mechanical energy harvesting and sports training monitoring
Authors: Duan Zhiyuan , Ge Nan , Hong-Kwan Cho , Sin-Young Song
Published: March 2024

Recently, intelligent wearable sensors applied in the field of smart sports have attracted much attention. Hence, we designed a pipe arrangement structure triboelectric nanogenerator (PA-TENG), and it can obtain mechanical energy and monitor sports motion. The triboelectric materials are composed of a polydimethylsiloxane layer attached to a silicone tube and nylon layer. The conductive copper attached to the silicone tube surface serves as a conductive electrode of the PA-TENG. Meanwhile, the soft silicone tube can endow the PA-TENG device with the ability to sense pressure. The results indicate that this silicone tube substrate can effectively adsorb conductive copper layers, and the conductive electrode layer still maintains good conductivity stability at different bending angles (15°–90°). The PA-TENG can achieve the maximum output power of 1.03 mW (matched load: 6 MΩ). The results indicate that the PA-TENG can attain the open-circuit voltage (Voc) of 190.05 V and the short-circuit current (Isc) of 1.98 μA. The transfer charge (Qsc) of the PA-TENG can arrive at 139.01 nC. The PA-TENG can drive the light-emitting diodes (LEDs), which demonstrates good practicality. Moreover, the PA-TENG can be installed on human joints (fingers, arms, knees, feet, etc.) as a monitoring sensor for various sports training, providing real-time sensing data for training. This research provides a novel pipe arrangement substrate for the wearable sports training sensor.
Reducing two-level systems dissipations in 3D superconducting niobium resonators by atomic layer deposition and high temperature heat treatment
Authors: Kalboussi Y. , Delatte B. , Bira S. , Dembele K. , Li X. , Miserque F. , Brun N. , Walls M. , Maurice J. L. , Dragoe D. , Leroy J. , Longuevergne D. , Gentils A. , Jublot-Leclerc S. , Jullien G. , Eozenou F. , Baudrier M. , Maurice L. , Proslier T.
Published: March 2024

Superconducting qubits have arisen as a leading technology platform for quantum computing, which is on the verge of revolutionizing the world's calculation capacities. Nonetheless, the fabrication of computationally reliable qubit circuits requires increasing the quantum coherence lifetimes, which are predominantly limited by the dissipations of two-level system defects present in the thin superconducting film and the adjacent dielectric regions. In this paper, we demonstrate the reduction of two-level system losses in three-dimensional superconducting radio frequency niobium resonators by atomic layer deposition of a 10 nm aluminum oxide Al2O3 thin films, followed by a high vacuum heat treatment at 650 °C for few hours. By probing the effect of several heat treatments on Al2O3-coated niobium samples by x-ray photoelectron spectroscopy plus scanning and conventional high resolution transmission electron microscopy coupled with electron energy loss spectroscopy and energy dispersive spectroscopy, we witness a dissolution of niobium native oxides and the modification of the Al2O3-Nb interface, which correlates with the enhancement of the quality factor at low fields of two 1.3 GHz niobium cavities coated with 10 nm of Al2O3.
Effect of the number and distribution of Al2O3 atomic layer deposition cycles within HfO2 layer on ferroelectric characteristics
Authors: Park Hyoungjin , Jeong Jiae , Kim Hyun Wook , Hong Eunryeong , Kim Nayeon , Jeon Seonuk , Kim Yunsur , Choi Hyeonsik , Woo Jiyong
Published: March 2024

We comprehensively analyze the effects of the number and distribution of Al2O3 atomic layer deposition (ALD) cycles into a 10-nm-thick HfO2 matrix on the ferroelectric switching behavior. An ALD cycle containing one pulse for Hf (or Al) precursor and one pulse of water as reactant is repeated 150 times for the given thickness of 10 nm. Spontaneous remnant polarization (Pr) is enabled through the formation of crystalline Al-doped HfO2 (Al:HfO2) by incorporating at least two Al2O3 ALD cycles evenly into the HfO2 film under annealing at 600 °C for 3 min following W top electrode (TE) deposition. When more than four Al2O3 cycles are used, the Al elements function as leakage sources rather than stressors, resulting in an open hysteresis loop and a weak endurance of 105 cycles. Notably, an improved 2 Pr of ∼9 μC/cm2 is achieved when the Al2O3 layers are concentrated near the lower region of the HfO2. On the other hand, as the Al2O3 layers are intensively located in the upper region of the HfO2, a dielectric response is observed in the polarization–voltage and current–voltage measurements. Our results indicate that the two mechanical stresses induced by the Al dopant with a size smaller than Hf and the difference in the thermal expansion coefficient between TE and Al:HfO2 effectively activate both the lower and upper sites. Therefore, many dipoles are observed to participate in the polarization owing to the stresses that are applied evenly throughout the Al:HfO2 layer to form the orthorhombic phase.
Conflict actors influence the dynamics of agropastoral policies to accommodate their preferences and expectations in Ghana
Authors: Brobbey Lawrence Kwabena , Agyei Frank Kwaku , Osei-Tutu Paul , Kyereh Boateng
Published: March 2024

In many sub-Saharan African countries, numerous studies ascribe biases and inconsistencies in agropastoral policies to the perennial farmer–herder conflicts. However, insights into the assumptions underlying agropastoral policies and the strategies that actors involved in the conflict use to influence these policies are limited in countries with high incidence of such conflicts. We engaged the ‘act of governmentality’ (ways of governing) to examine how agropastoral policies in Ghana from colonial to contemporary times have influenced farmer–herder conflicts, and examined the strategies used by key conflict actors to influence the agropastoral policy process. Data were collected through documentary review, interviews, focus group discussions and facilitated workshops with a range of conflict actors such as farmers, pastoralists, chiefs, farmer and herder associations, and public officials. Our analyses indicated that whereas the colonial administration facilitated cattle ranching among natives of the Gold Coast, the postcolonial administration changed the approach by adopting a seemingly hostile strategy that largely neglected pastoralism for almost five decades. The state now favours sedentarisation, an approach that has been rebuffed by many farmers, farming communities, and some pastoralists. Policy inconsistencies have created tensions and a dynamic struggle across spatial scales, with each actor coalition employing diverse strategies to influence agropastoral policies to accommodate their preferences and expectations. The outcome of each policy cycle became an input for further contestation in a resource-depleting process that failed to produce equitable outcomes. Achieving a sustainable negotiated solution requires moving beyond the current segmentation towards well-structured and inclusive multi-stakeholder dialogue that allows for proper consideration of all actors’ concerns.
Improved RNA stability estimation through Bayesian modeling reveals most
Salmonella
transcripts have subminute half-lives
Authors: Jenniches Laura , Michaux Charlotte , Popella Linda , Reichardt Sarah , Vogel Jörg , Westermann Alexander J. , Barquist Lars
Published: March 2024

RNA decay is a crucial mechanism for regulating gene expression in response to environmental stresses. In bacteria, RNA-binding proteins (RBPs) are known to be involved in posttranscriptional regulation, but their global impact on RNA half-lives has not been extensively studied. To shed light on the role of the major RBPs ProQ and CspC/E in maintaining RNA stability, we performed RNA sequencing of
Salmonella enterica
over a time course following treatment with the transcription initiation inhibitor rifampicin (RIF-seq) in the presence and absence of these RBPs. We developed a hierarchical Bayesian model that corrects for confounding factors in rifampicin RNA stability assays and enables us to identify differentially decaying transcripts transcriptome-wide. Our analysis revealed that the median RNA half-life in
Salmonella
in early stationary phase is less than 1 min, a third of previous estimates. We found that over half of the 500 most long-lived transcripts are bound by at least one major RBP, suggesting a general role for RBPs in shaping the transcriptome. Integrating differential stability estimates with cross-linking and immunoprecipitation followed by RNA sequencing (CLIP-seq) revealed that approximately 30% of transcripts with ProQ binding sites and more than 40% with CspC/E binding sites in coding or 3′ untranslated regions decay differentially in the absence of the respective RBP. Analysis of differentially destabilized transcripts identified a role for ProQ in the oxidative stress response. Our findings provide insights into posttranscriptional regulation by ProQ and CspC/E, and the importance of RBPs in regulating gene expression.
Biodiversity and productivity in eastern US forests
Authors: Liu Yunpeng , Hogan J. Aaron , Lichstein Jeremy W. , Guralnick Robert P. , Soltis Douglas E. , Soltis Pamela S. , Scheiner Samuel M.
Published: March 2024

Despite experimental and observational studies demonstrating that biodiversity enhances primary productivity, the best metric for predicting productivity at broad geographic extents—functional trait diversity, phylogenetic diversity, or species richness—remains unknown. Using >1.8 million tree measurements from across eastern US forests, we quantified relationships among functional trait diversity, phylogenetic diversity, species richness, and productivity. Surprisingly, functional trait and phylogenetic diversity explained little variation in productivity that could not be explained by tree species richness. This result was consistent across the entire eastern United States, within ecoprovinces, and within data subsets that controlled for biomass or stand age. Metrics of functional trait and phylogenetic diversity that were independent of species richness were negatively correlated with productivity. This last result suggests that processes that determine species sorting and packing are likely important for the relationships between productivity and biodiversity. This result also demonstrates the potential confusion that can arise when interdependencies among different diversity metrics are ignored. Our findings show the value of species richness as a predictive tool and highlight gaps in knowledge about linkages between functional diversity and ecosystem functioning.
Ligand-induced protein transition state stabilization switches the binding pathway from conformational selection to induced fit
Authors: Stenström Olof , Diehl Carl , Modig Kristofer , Akke Mikael
Published: March 2024

Protein–ligand complex formation is fundamental to biological function. A central question is whether proteins spontaneously adopt binding-competent conformations to which ligands bind conformational selection (CS) or whether ligands induce the binding-competent conformation induced fit (IF). Here, we resolve the CS and IF binding pathways by characterizing protein conformational dynamics over a wide range of ligand concentrations using NMR relaxation dispersion. We determined the relative flux through the two pathways using a four-state binding model that includes both CS and IF. Experiments conducted without ligand show that galectin-3 exchanges between the ground-state conformation and a high-energy conformation similar to the ligand-bound conformation, demonstrating that CS is a plausible pathway. Near-identical crystal structures of the apo and ligand-bound states suggest that the high-energy conformation in solution corresponds to the apo crystal structure. Stepwise additions of the ligand lactose induce progressive changes in the relaxation dispersions that we fit collectively to the four-state model, yielding all microscopic rate constants and binding affinities. The ligand affinity is higher for the bound-like conformation than for the ground state, as expected for CS. Nonetheless, the IF pathway contributes greater than 70% of the total flux even at low ligand concentrations. The higher flux through the IF pathway is explained by considerably higher rates of exchange between the two protein conformations in the ligand-associated state. Thus, the ligand acts to decrease the activation barrier between protein conformations in a manner reciprocal to enzymatic transition-state stabilization of reactions involving ligand transformation.
Supramolecular coordination platinum metallacycle–based multilevel wound dressing for bacteria sensing and wound healing
Authors: Li Wen-Zhen , Wang Xiao-Qiang , Liu Ling-Ran , Xiao Ju , Wang Xin-Qiong , Ye Yu-Yuan , Wang Zi-Xin , Zhu Mai-Yong , Sun Yao , Stang Peter J. , Sun Yan
Published: March 2024

The exploitation of novel wound healing methods with real-time infection sensing and high spatiotemporal precision is highly important for human health. Pt-based metal-organic cycles/cages (MOCs) have been employed as multifunctional antibacterial agents due to their superior Pt-related therapeutic efficiency, various functional subunits and specific geometries. However, how to rationally apply these nanoscale MOCs on the macroscale with controllable therapeutic output is still challenging. Here, a centimeter-scale Pt MOC film was constructed via multistage assembly and subsequently coated on a N,N′-dimethylated dipyridinium thiazolo[5,4-d]thiazole (MPT)-stained silk fabric to form a smart wound dressing for bacterial sensing and wound healing. The MPT on silk fabric could be used to monitor wound infection in real-time through the bacteria-mediated reduction of MPT to its radical form via a color change. The MPT radical also exhibited an excellent photothermal effect under 660 nm light irradiation, which could not only be applied for photothermal therapy but also induce the disassembly of the Pt MOC film suprastructure. The highly ordered Pt MOC film suprastructure exhibited high biosafety, while it also showed improved antibacterial efficiency after thermally induced disassembly. In vitro and in vivo studies revealed that the combination of the Pt MOC film and MPT-stained silk can provide real-time information on wound infection for timely treatment through noninvasive techniques. This study paves the way for bacterial sensing and wound healing with centimeter-scale metal-organic materials.
Hydroclimatic changes on multiple timescales since 7800 y BP in the winter precipitation–dominated Central Asia
Authors: Tan Liangcheng , Cheng Hai , Li Dong , Orozbaev Rustam , Li Yanzhen , Xu Hai , Edwards R. Lawrence , Song Yougui , Ma Le , Lin Fangyuan , Sinha Ashish , An Zhisheng
Published: March 2024

Central Asia (CA) is one of the world’s most significant arid regions, which is markedly impacted by global warming. A better understanding of the dynamical processes governing its Holocene climate variability is critical for a better understanding of possible future impacts of climate change in the region. To date, most of the existing CA paleoclimate records are from the summer precipitation–dominated eastern CA (ECA), with few records from the winter precipitation–dominated western CA (WCA). Here, we present a precisely dated (~6‰) and highly resolved (<4-y) record of hydroclimatic variations from the WCA covering the period between 7,774 and 656 y BP. Utilizing multiple proxies (δ
18
O, δ
13
C, and Sr/Ca) derived from a stalagmite from the Fergana Valley, Kyrgyzstan, we reveal a long-term drying trend in WCA, which is in contrast with the wetting trend in ECA. We propose that different responses of winter and summer westerly jets to seasonal solar insolation over the past 8,000 y may have resulted in an antiphased precipitation relationship between the WCA and ECA. Our data contain dominant quasiperiodicities of 1,400, 50 to 70, and 20 to 30 y, indicating close connections between the WCA climate and the North Atlantic. We further identified a series of droughts and pluvials on centennial-to-decadal timescales, which may have influenced regional societies and trans-Eurasian culture exchanges during historical and prehistorical times.
Final report, ongoing key comparison BIPM.QM-K1, ozone at ambient level, comparison with NPL, June 2022
Authors: Viallon Joële , Idrees Faraz , Moussay Philippe , Wielgosz Robert , Marval Jesus , Sweeney Bryan , Cheong Jody
Published: March 2024

Main text

As part of the ongoing key comparison BIPM.QM-K1, a comparison has been performed between the ozone national standard of United Kingdom maintained by the National Physical Laboratory (NPL) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM). The instruments have been compared over a nominal ozone amount fraction range of 0 nmol mol−1 to 500 nmol mol−1.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Exploring ion mobility mechanisms in poly indolequinone polymers: a case study on black soldier fly melanin
Authors: Ambrico M , Mostert A B , Ambrico P F , Phua J , Mattiello S , Gunnella R
Published: March 2024

Black soldier fly (BSF) melanin is a new supply of the brown-black pigment eumelanin. Given that eumelanin is a model bioelectronic material for applications such as medical devices and sensors, understanding BSF melanin’s electrical properties is important to confirm its viability as an advanced material. Presented here is a systematic, hydration dependent alternating current study of BSF melanin utilising both H2O and D2O vapours. There is a clear difference between the vapours, enabling a thorough analysis including Nyquist plots with model circuit analysis, broad band dielectric spectroscopic modelling as well as applying the Trukhan model to understand free ion concentration and mobility changes as a function of hydration. We find that BSF melanin behaves similarly to previous reports on synthetic systems, and the analysis here sheds additional light on potential charge transport changes. Significantly, a key finding is that there are two different mobility mechanisms for ion transport depending on hydration.
Antiferromagnetically ordered topological semimetals in Hubbard model with spin-orbit coupling
Authors: Goyal Garima , Singh Dheeraj Kumar
Published: March 2024

We examine the possible existence of Dirac semimetal with magnetic order in a two-dimensional system with a nonsymmorphic symmetry by using the Hartree–Fock mean-field theory within the Hubbard model. We locate the region in the second-neighbor spin–orbit coupling vs Hubbard interaction phase diagram, where such a state is stabilized. The edge states for the ribbons along two orthogonal directions concerning the orientation of in-plane magnetic moments are obtained. Finally, the effect of the in-plane magnetic field, which results in the stabilization of the Weyl semimetallic (WSM) state, and the nature of the edge states corresponding to the WSM state for ribbon geometries are also explored.
Formation of Ar2+ ions in cold argon plasmas through the ternary recombination mechanism
Authors: Nongni F T , Kalus R , Benhenni M , Gadéa F X , Yousfi M
Published: March 2024

A general scheme for calculating ternary recombination rate constants of atomic species based on a hybrid quantum–classical nonadiabatic dynamics approach is presented and applied to the specific case of the ternary recombination of atomic ions of argon in cold argon plasmas. Rate constants are reported for both fine-structure states of theAr+ion,2P3/2and2P1/2,T = 300 K, and for selected values of the reduced electric field. A thorough comparison with the literature data available forT = 300 K and a couple of close temperatures is performed with a favorable agreement achieved. It is shown that the excitedAr+(2P1/2)ions may contribute to the formation of dimer ions,Ar2+, as efficiently as the ground-state ions,Ar+(2P3/2), due to fast internal conversion of the electronic energy, which takes place in ternary collision complexes,Ar+/Ar/Ar.
Highly sensitive surface acoustic wave magnetic field sensor based on the loss mechanism
Authors: Wu Yutong , Cui Baile , Jia Yana , Zhou Zihan , Hu Wenbin , Bai Feiming , Wang Wen , Xue Xufeng , Liang Yong
Published: March 2024

Currently, the surface acoustic wave (SAW) magnetic field sensing technique utilises the SAW velocity/frequency mechanism of magnetoacoustic interaction as an indicator of the magnetic sensitivity mechanism. However, this method has low sensitivity and poor stability. To address this problem, a dynamic magnetoelastic coupling theoretical model is constructed to theoretically simulate the influence of the ΔE effect of magnetically sensitive thin films on SAW propagation attenuation. This study describes a high-sensitivity SAW magnetic field sensing mechanism based on magnetoacoustic attenuation. The simulation results show a clear relationship between the acoustic propagation loss and external magnetic field, indicating a structure-property relationship. An amorphous soft magnetic material (Fe90Co10)78Si12B10 was used as a magnetically sensitive thin film due to its high permeability, low coercivity (Hc), low hysteresis, ease of magnetisation and demagnetisation. SAW magnetosensitive device operating on a frequency of 200 MHz has been experimentally developed using a standard semiconductor photolithography process. A SiO2 layer was deposited on a 36° YX-LiTaO3 substrate as a waveguide, and a (Fe90Co10)78Si12B10 layer was on the top of the propagation area as a magnetosensitive film. The experimental results showed that the acoustic loss change due to the magnetic field variation was 4.63 dB within a magnetic field range of 0 Oe to ±10 Oe, which agreed with the theoretical results. The sensor had a sensitivity of 0.7546 dB Oe−1 within the range of 0–4 Oe and the lower detection limit of magnetic fields was 0.272 Oe, low hysteresis error of 0.54%, multiple repeatability error of 0.13%, excellent repeatability and stability were achieved in the experiments from the developed sensing device.
Fiber design and performance analyses for optical multiplexing: terahertz optical communications
Authors: Anowar Kabir Md , Paul Bikash Kumar , Hossain Md Selim , Uddin Muhammad Shahin , Morshed Monir
Published: March 2024

Multiplexing is the process of combining multiple signals at a single channel. Orbital Angular Momentum (OAM) is one of the main multiplexing techniques for optical data transmissions. This paper examines and suggests a hollow core with four layers of semilunar air-hole-shaped circular photonic crystal fiber (PCF) capable of transmitting terahertz (THz) OAM information-carrying modes. By using the full vector finite element method (FEM), OAM multiplexing is analyzed for the proposed fiber. All the THz OAM-based factors are analyzed at a frequency band ranging from 400 GHz to 800 GHz. For the first time, some important PCF factors such as effective refractive index difference (ERID), dispersion profile (DP), OAM purity, confinement loss (CL), effective mode area (ERA), and numerical aperture (NA) are quantitatively discussed with applications. The proposed design supports 50 OAM modes with ERID up to 10−3. The PCF has a CL of approximately 10–10 dB cm−1 and the lowest dispersion profile is 0.3581 ps/THz/cm. Furthermore, the OAM purity is around 97%. Nonetheless, the proposed design can be used in THz-OAM transmission and high optical fiber communications.
On stability behaviors of 5D M-theory black objects
Authors: Belhaj Adil , Bouhouch Abderrahim
Published: March 2024

Using N = 2 supergravity formalism, we investigate certain behaviors of five-dimensional black objects from the compactification of M-theory on a Calabi–Yau three-fold. The manifold has been constructed as the intersection of two homogeneous polynomials of degrees (ω + 2, 1) and (2, 1) in a product of two weighted projective spaces given by

WP

4

(
ω
,
1
,
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. First, we determine the allowed electric charge regions of the BPS and non BPS black holes obtained by wrapping M2-branes on appropriate two cycles in such a proposed Calabi–Yau three-fold. After that, we calculate the entropy of these solutions which takes a maximal value corresponding to ω = 1 defining the ordinary projective space

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. For generic values of ω, we show that the non BPS states are unstable. Then, we conduct a similar study of five-dimensional black strings. Concerning the allowed magnetic charge regions of the BPS and non BPS black stringy solutions derived from M5-branes on dual divisors, we calculate the tension taking a minimal value for

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. By determining the recombination factor, we show that the non-BPS black string states are stable in the allowed regions in the magnetic charge space.
Impurity leakage mechanisms in the Wendelstein 7-X island divertor under friction-dominated conditions
Authors: Winters V.R. , Reimold F. , Feng Y. , Perseo V. , Beurskens M. , Bozhenkov S. , Brunner K.J. , Fuchert G. , Koenig R. , Knauer J. , Krychowiak M. , Pasch E. , Scott E. , Zhang D. ,   the W7-X Team
Published: March 2024

The EMC3-Eirene code was used to study the main impurity leakage mechanism for the island divertor in the standard magnetic field configuration. It was found that under experimentally accessible plasma scenarios in the last experimental campaign, the majority of the island scrape-off layer was friction-force dominated. The impurity force balance was only thermal force dominated for upstream locations closed to the last closed flux surface, beyond the island X-point. No impurity neutral ionization was found in this location and hence the parallel impurity transport provides excellent impurity retention. It was found that impurities approach the confinement region nonetheless via perpendicular transport across the island O-point near the parallel flow stagnation region. This finding points out the specific role of the parallel flow stagnation region in providing lower parallel convective transport and long impurity residence times, which makes non-parallel transport channels more important or even the dominant driver of impurity leakage. In line with the relevance of the particle build-up in the flow stagnation region, different retention behavior as a function of density is seen for various species, which is shown to be due to ionization length changes as the plasma background density is increased.
Measurement of elements by portable x-ray fluorescence spectrometry for the study of adsorption processes: the case of Pb2+ adsorption on soybean straw biochar
Authors: Wannaz Eduardo D , Medina Rocío , Pardo Sheila D , Medina Gonzalo P Barbero , Blanco Andrés , Salazar María Julieta
Published: March 2024

This study evaluated the reliability of portable X-ray fluorescence (pXRF) in Pb2+ adsorption kinetics and isotherm experiments using soybean straw biochar. The research aimed to compare pXRF results with those obtained through traditional atomic absorption spectrometry (AAS). Soybean straw biochar, produced at 400 °C, was employed as the adsorbent for Pb2+. The efficiency of adsorption was assessed using Langmuir and Freundlich models. The kinetics of Pb2+ adsorption was analysed through pseudo-first-order and pseudo-second-order models. The pseudo-second-order model described the kinetics of Pb2+ adsorption on biochar better than the pseudo-first order model. Importantly, the pXRF technique demonstrated comparable results to those of AAS, making it a reliable and resource-efficient method for studying Pb2+ kinetics. The results of the isotherm analyses fit the Langmuir model, indicating a desirable and irreversible adsorption of Pb2+ on biochar. PXRF measurements on biochar allowed simultaneous observations of Pb2+ adsorption and K+ and Ca2+ desorption, highlighting ionic exchange as the primary adsorption mechanism. In conclusion, our results showcased the applicability of pXRF for Pb+2 adsorption studies in biochars, offering a valuable alternative to traditional methods. The findings contribute to the understanding of biochar as an effective adsorbent for heavy metals, emphasizing the potential of pXRF for cost-effective and efficient environmental research. In this study, we present a novel and detailed procedure that will allow other researchers to continue their studies on Pb2+ adsorption on biochar or similar matrices, significantly reducing the resources and time used and enabling the simultaneous study of the behavior of other ions participating in the process.
Investigation of evolution of γ
N phase and its effect on conductivity and corrosion resistance of plasma-nitrided 316 L stainless steel bipolar plate for proton exchange membrane fuel cell
Authors: Liu Chunpeng , Li Chuanwei , Ye Zhenhua , Suo Zhongyuan , Jiang Feng , Gu Jianfeng
Published: March 2024

In this work, the evolution of γ
N phase and its effect on conductivity and corrosion resistance of plasma-nitrided 316 L stainless steel bipolar plate was investigated. The results shows that a certain thickness of uniform γ
N phase layer was formed after plasma-nitriding treatment. As the increasing in plasma-nitriding time, the thickness of γ
N phase layer and nitrogen atoms in γ
N phase layer was increased gradually. As the plasma-nitriding time was larger than 10 h, a large amount of cracks was formed in γ
N phase layer because the nitrogen atoms were diffused into γ phase to cause the serious lattice distortion. When the plasma-nitriding time was reached to 24 h, the Fe4N compound was found on the sample surface. After plasma-nitriding treatment, the conductivity and corrosion resistance of the sample was obviously enhanced compared with the untreated sample. With the increasing in the thickness of γ
N phase layer, the interfacial contact resistance (ICR) and corrosion current of the sample was gradually reduced. The ICR of the sample was reduced to 7 mΩ under 10 h condition. However, the formation of Fe4N compound and high roughness contributed to the increase of ICR of the sample under 24 h condition, its value was reached to 15 mΩ. When the plasma-nitriding time was larger than 10 h, the corrosion resistance of the sample became poor. The formation of cracks in γ
N phase layer and the high surface roughness resulted in the degradation of corrosion resistance of the sample. Under 5 h condition, the comprehensive properties of the sample were the best. The ICR and corrosion of the sample were current conductivity and corrosion resistance of the sample were 15 mΩ and 5.1 μA cm−2, which were low 4 times and 15 times compared with the untreated sample.
Multimode fiber-coupled VIPA spectrometer for high-throughput Brillouin imaging of biological samples
Authors: Bouvet Pierre , Clément Flora , Papoz Anastasia , Dehoux Thomas , Baritaux Jean-Charles
Published: March 2024

Slow acquisition time and instrument stability are the two major limitations for the application of confocal Brillouin microscopy to biological materials. Although overlooked, coupling the microscope to the spectrometer with a multimode fiber (MMF) is a simple yet viable solution to increase both the detection efficiency and the stability of the classical single-mode fiber-coupled virtually imaged phase array (VIPA) instruments. Here we implement the first successful MMF-coupled VIPA spectrometer for confocal Brillouin applications and present a dimensioning strategy to optimize its collected power. The use of an MMF brings a tremendous improvement on the stability of the spectrometer that allows performing experiments over several weeks without realignment of the device. For instance, we map the Brillouin shift and linewidth in growing ductal and acinar organoids with a spatial resolution of

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dwell time. Our results clearly reveal the formation of a lumen in these organoids. Careful examination of the data also suggests an increase in the viscosity of the cells of the assembly.
Using positional tracking to improve abdominal ultrasound machine learning classification
Authors: Lawley Alistair , Hampson Rory , Worrall Kevin , Dobie Gordon
Published: March 2024

Diagnostic abdominal ultrasound screening and monitoring protocols are based around gathering a set of standard cross sectional images that ensure the coverage of relevant anatomical structures during the collection procedure. This allows clinicians to make diagnostic decisions with the best picture available from that modality. Currently, there is very little assistance provided to sonographers to ensure adherence to collection protocols, with previous studies suggesting that traditional image only machine learning classification can provide only limited assistance in supporting this task, for example it can be difficult to differentiate between multiple liver cross sections or those of the left and right kidney from image post collection. In this proof of concept, positional tracking information was added to the image input of a neural network to provide the additional context required to recognize six otherwise difficult to identify edge cases. In this paper optical and sensor based infrared tracking (IR) was used to track the position of an ultrasound probe during the collection of clinical cross sections on an abdominal phantom. Convolutional neural networks were then trained using both image-only and image with positional data, the classification accuracy results were then compared. The addition of positional information significantly improved average classification results from ∼90% for image-only to 95% for optical IR position tracking and 93% for Sensor-based IR in common abdominal cross sections. While there is further work to be done, the addition of low-cost positional tracking to machine learning ultrasound classification will allow for significantly increased accuracy for identifying important diagnostic cross sections, with the potential to not only provide validation of adherence to protocol but also could provide navigation prompts to assist in user training and in ensuring adherence in capturing cross sections in future.