bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of thermal radiatively Jeffrey fluid through an annulus region between two flexible tubes with entropy generation
Authors: Fayyaz A , Abbas Z , Rafiq M Y
Published: September 2024

Endoscope is a very important tool for medical diagnosis and they have many clinical applications. The endoscope now is a very important tool used for determining real reasons responsible for many problems in the human organs in which the fluid is transported by peristaltic pumping such as the stomach, small intestine, etc Therefore, this paper discusses the influence of an endoscope on the peristaltic flow of a Jeffery fluid in an annulus by considering the entropy generation. The inner tube which is uniform and rigid fulfilled the slip conditions, while the outer tube having a sinusoidal wall has a no-slip condition. The impacts of thermal radiation and viscous dissipation are also considered in the energy equation. The flow analysis has been developed for low Reynolds number and long wavelength approximation. The analytical solution for velocity, pressure gradient, temperature, streamlines, entropy generation, and Bejan number is obtained using the perturbation method, and then the obtained results are plotted to see the influence of different physical parameters. The major outcomes disclosed that the velocity profile decreases near the region of the inner tube due to the slip parameter and the inner tube radius. However, it increases due to the inner tube velocity and amplitude ratio. The temperature distribution rises with the Brinkman number. On the other hand, it declined for the radiation parameter. Furthermore, the entropy generation increases for the Brinkman number, but the Bejan number decreases for the Brinkman number. The present study has application in endoscopes, which is important to diagnose problems in internal organs. Also, the variation of pressure gradient helps to maintain the flow rate which is essential during the insertion of the catheter into the artery.
Luminescence and dielectric investigations of crystalline niobate nanoceramics prepared through aqueous chemical process
Authors: Sarkar Kakali , Kumar Vivek
Published: September 2024

The present study reflects the synthesis of MgNb2O6 using hydrofluoric acid via a wet chemical approach, followed by characterizations involving XRD, electron microscopy, Raman spectroscopy, optical analyses, and impedance spectroscopy. The crystallite size of the synthesized material was determined to be 44 nm through XRD analysis. The lattice parameters of MgNb2O6 a, b, and c, were found to be 14.1998 Å, 5.6844 Å, and 4.9813 Å, respectively. Raman spectroscopy identified molecular bonds ranging from 253 to 1011 cm−1, mainly indicating the presence of metal oxide bonds. EDX spectra confirmed the presence of Mg, Nb, and O atoms in the prepared ceramics, indicating phase purity. FESEM analysis revealed a grain size of approximately 48 nm, with the presence of agglomerated grains. Bright spots in the SAED pattern observed by HRTEM confirmed the crystallinity of the prepared niobate materials, with the HRTEM microstructure showing a particle size near 49 nm. The crystallite size by XRD, grain size by FESEM, and particle size by HRTEM are in accordance with each other. The direct band gap was determined to be approximately 2.76 eV using UV-Visible spectroscopy. Additionally, MgNb2O6 materials exhibited a broad and strong photoluminescence emission near 445 nm with excitation at 270 nm, possibly indicating the presence of radiative defects in the crystalline nanostructure. Furthermore, impedance studies conducted between 40 and 110 MHz demonstrated a decrease in the dielectric constant at higher frequencies, reaching 21.06 at 110 MHz. A low dielectric loss was also observed at 110 MHz. The moderate band gap and strong room-temperature photoluminescence in the visible range make magnesium niobates suitable for possible applications in optical devices. This investigation shows that a dielectric constant near 21 and low dielectric loss can be achieved in the high-frequency range around 110 MHz.
Phase-space representation of coherent states generated through SUSY QM for tilted anisotropic Dirac materials
Authors: O-Campa Daniel , Díaz-Bautista Erik
Published: September 2024

In this paper, we examine the electron interaction within tilted anisotropic Dirac materials when subjected to external electric and magnetic fields possessing translational symmetry. Specifically, we focus on a distinct non-zero electric field magnitude, enabling the decoupling of the differential equation system inherent in the eigenvalue problem. Subsequently, employing supersymmetric quantum mechanics facilitates the determination of eigenstates and eigenvalues corresponding to the Hamiltonian operator. To delve into a semi-classical analysis of the system, we identify a set of coherent states. Finally, we assess the characteristics of these states using fidelity and the phase-space representation through the Wigner function.
Controlled single step synthesis, structural and electrode response of honeycomb layered Li3Co2SbO6
Authors: Singh Arvind , Chakrabarti Shamik , Nair Manjula G , Thakur A K
Published: September 2024

We report, for the first time, a single step synthesis process of Li3Co2SbO6 in air medium using the solid state reaction route. The structural analysis confirmed single phase layered crystal structure comprising 2D diffusion path along a-axis and b-axis. The Rietveld refinement of Li3Co2SbO6 yielded monoclinic crystal structure with C2/m space group having cell parameters, a = 5.216 A°, b = 8.989 A° and c = 5.171 A° with Li/Co mixed occupancy. The TEM analysis corroborated the layered structure which is consistent with x-ray analysis. Raman and FTIR analysis confirmed the presence of -CoO6 and -SbO6 octahedra in Li3Co2SbO6 with edge shared arrangement to form a layered stack comprising tunnel type pathway for Li+ ion transport. The estimated electrical conductivity of Li3Co2SbO6 is found to be ∼6.9 × 10−8 Scm−1 with a band gap ∼ 3.5 eV that suggests poor electronic transport for storage cells. This was observed in the electrochemical response of the Li || LiPF6(EC/EMC) || Li3Co2SbO6 cell. The 1st discharge capacity of Li3Co2SbO6 has been found to be a meagre 45 mAhg−1. Despite lower reversible capacity due to poor electrical transport, stable coulombic efficency observed up to 100 cycles suggest the feasibility of improvements in the electrical and charge transport properties.
The constancy of the speed of the light comes from the causality principle
Authors: Kim Do-Hyung
Published: September 2024

It is well-known that Einstein's relativity theory begins with a principle, the constancy of the speed of the light. However, the principle does not meet our usual, Galilean perspectives. Then, we can ask : What is the origin of the principle? What makes the speed of the light constant to everyone? In this work, it is argued that, in mathematically rigorous terms, the principle is almost equivalent to the local causality principle and this can be interpreted as ‘Even if time machine exists, it depends not on the local structure but on the global structure, or equivalently, on the topology of our universe.’ In mathematical terms, we show that any diffeomorphism between spacetimes is conformal if the diffeomorphism preserves pointwise harmonicity of functions.
High-sensitive MXene and GST-based tunable refractive index sensor for the infrared and visible spectrum from multipurpose sensing applications
Authors: Sbeah Zen A , Sorathiya Vishal , Alwabli Abdullah , Jaffar Amar Y , Aldosari Fahd M , Faragallah Osama S
Published: September 2024

In this paper, a sensor with a multi-layered structure based on MXene and chalcogenide which is based on germanium (Ge)-antimony (Sb) telluride (Te) (GST) as an active plasmonic material is designed. The design is simulated in 2D. The design is a general sensor to detect refractive index from 1 to 1.15. Here, the design structure is arranged by placing the analyte on top. The middle metal layer is considered Ag/Au/Al/Cu to identify the effect of the metal layer on overall absorption and reflector. The GST layer is modeled with two distinct states: aGST and cGST, allowing for the analysis of the structure's tunable behavior based on the varying properties of these states. Optimisation and validation for parameters like height, width, and other metals, such as Ag/Au/Cu/Al processes, were conducted to ensure optimal device performance. The proposed refractive index sensor offers a high sensitivity variation ranging from 80 deg RIU−1 to 770 deg/RIU. The bandwidth and resonant area show significant variation between the two states of GST material. In other words, the proposed refractive index sensor can be used as a lab-on-chip biosensor. This proposed sensor provides potential application in the research of biomolecular detection and chemical testing.
Tuning the IcRn value of YBCO step edge Josephson junction through Ar+ ion irradiation
Authors: Kumar Sandeep , Khare Neeraj
Published: September 2024

YBCO Step edge Josephson junctions are fabricated on single crystal MgO (100) substrates, and the effect of Ar+ ion irradiation on the critical current (Ic) and normal state resistance (Rn) is studied. It is shown that on the appropriate exposure of the YBCO step edge junction to Ar+ ion irradiation, the IcRn product of the junction can be enhanced up to 0.66 mV at 77 K, which is sufficiently good for many applications. With the increase in the exposure time of Ar+ ion irradiation, the value of Ic decreases, and the Rn value increases. After irradiating for 4 min, Ic as low as 70 μA and Rn as high as ∼9.4 Ω have been obtained at 77 K. It is found that for higher exposure time, the junction behavior tends to SIS-type junctions. The mechanism responsible for the decrease in Ic and increase in Rn seems to be associated with the vacancies as well as displacement of oxygen atoms caused by the ion irradiation, which causes the suppression of superconducting parameters as the superconducting properties critically depend on the concentration of the oxygen atoms in the Cu-O planes.
Spectral prediction of all dielectric nanopore metasurface based on DBO-DNN model
Authors: Chen Ying , Li Weiqiang , Wang Qinghui , Zhao Guoting , Shi Moqing
Published: September 2024

Based on the optical properties of symmetric structures independent of each other in the orthogonal direction, a class of all-dielectric nanohole array metasurfaces symmetrical along the diagonal is designed. By adding nanopores of different shapes to break the symmetry of the periodic unit structure, the double Fano resonance is excited. The spectral characteristics of metasurfaces with the same structure type are studied by finitedifference timedomain (FDTD) method. The deep neural network (DNN) is used to establish the nonlinear mapping relationship between the input structural parameters and the transmission spectrum. The number of hidden layers in the DNN and the number of neurons in each layer are optimized by the dung beetle optimization (DBO) algorithm. Therefore, the number of hidden layers of the model is determined to be 5, and the number of neurons in each layer is 120, 30, 150, 60, 90, respectively. The mean square error (MSE) is used to evaluate the training effect of DNN after optimization search. After 35,000 epochs of training, MSE is reduced to 0.0003926. The influence of different gradient descent optimization algorithms on the prediction results is explored respectively, and it is found that Adamax is the most effective. The results show that the prediction model can predict the spectrum within 1 s. Compared with the traditional simulation method, the simulation time is effectively saved. Meet the requirements of efficient and rapid design of ultra-thin lenses. For the same type of metasurface structure, the transmission spectrum can be accurately predicted without multiple data sets.
Graphene-based hybrid metasurfaces with quasi-bound states in the continuum for manipulating terahertz absorption
Authors: Wang Baoku , Wang Feng , Tian Fengjun , Li Li
Published: September 2024

We present a graphene-based hybrid metasurface with quasi-bound states in the continuum (BICs) for manipulating terahertz (THz) wave absorption. By the strategic application of structural perturbations for the THz metasurface, the symmetry-protected BICs transforms into quasi-BICs. The incorporation of graphene adeptly satisfies the critical coupling condition, thereby facilitating the attainment of the theoretical maximum absorption of 0.5 for the quasi-BICs in the THz region. And the Q-factor of the quasi-BIC can be up to 2755. Moreover, the metasurface exhibits a distinctive ability for unique tuning and efficient absorption of terahertz waves by varying the asymmetry parameter and Fermi levels. This work provides promising strategies for manipulating terahertz wave absorption.
(Pseudo-)Synthetic BRST quantisation of the bosonic string and the higher quantum origin of dualities
Authors: Patrascu Andrei T
Published: September 2024

In this article I am arguing in favour of the hypothesis that the origin of gauge and string dualities in general can be found in a higher-categorical interpretation of basic quantum mechanics. It is interesting to observe that the Galilei group has a non-trivial cohomology, while the Lorentz/Poincare group has trivial cohomology. When we constructed quantum mechanics, we noticed the non-trivial cohomology structure of the Galilei group and hence, we required for a proper quantisation procedure that would be compatible with the symmetry group of our theory, to go to a central extension of the Galilei group universal covering by co-cycle. This would be the Bargmann group. However, Nature didn’t choose this path. Instead in nature, the Galilei group is not realised, while the Lorentz group is. The fact that the Galilei group has topological obstructions leads to a central charge, the mass, and a superselection rule, required to implement the Galilei symmetry, that forbids transitions between states of different mass. The topological structure of the Lorentz group however lacks such an obstruction, and hence allows for transitions between states of different mass. The connectivity structure of the Lorentz group as opposed to that of the Galilei group can be interpreted in the sense of an ER=EPR duality for the topological space associated to group cohomology. In string theory we started with the Witt algebra, and due to similar quantisation issues, we employed the central extension by co-cycle to obtain the Virasoro algebra. This is a unique extension for orientation preserving diffeomorphisms on a circle, but there is no reason to believe that, at the high energy domain in physics where this would apply, we do not have a totally different structure altogether and the degrees of freedom present there would require something vastly more general and global.
Aging characterization of dielectric materials using microstrip spiral resonator sensor: application in high frequency range, up to 18 GHz
Authors: Bensahla Naziha , Amar Hichem , Amir Mounir , Tebache Soufiane , Hedir Abdallah
Published: September 2024

This current work aims to propose a complete microwave procedure for dielectric materials aging characterization. To achieve this aim, a microstrip spiral resonator sensor, based on printed circuit board (PCB) technology, is designed to attend polyvinyl chloride (PVC) aging behavior through microwave measurements. The resonator is composed of a spiral microstrip, excited by coupling 50-Ohm transmission line on the top layer of the substrate; meanwhile a rectangular slot is etched in the bottom layer, behind the spiral shape to achieve high inductive effect. Structure optimization was conducted using high-frequency structure simulator (HFSS). The sensor is then used as a holder of the UV-aged PVC material while reflection (S11) and transmission (S21) coefficients are measured by vector network analyzer (VNA) in high frequency range, up to 18 GHz. The aging effect is finally perceived by observing the frequency shift of the resonance frequency between the empty and the aged-PVC loaded sensor, together with a variation in the S21 parameter amplitude. It is then found that for 864 h of UV-exposure is provided more than 0.45% frequency shift and about 4.67% decrease in electromagnetic energy transmission. Moreover, comparison between S11 and S21 results reveals that using S11 parameter is more practical to investigate material aging as it allows for simple visual checking of the frequency shift.
A new spline method on graded mesh for fourth-order time-dependent PDEs: application to Kuramoto-Sivashinsky and extended Fisher-Kolmogorov equations
Authors: Sharma Sachin , Sharma Naina
Published: September 2024

In this research, we introduce a two-tier non-polynomial spline approach with graded mesh discretization for addressing fourth-order time-dependent partial differential equations, which find applications in various physical scenarios like the nonlinear Kuramoto-Sivashinsky equation and extended Fisher-Kolmogorov equation. Our method involves considering three spatial points at each time step for scheme development, achieving spatial accuracy of three and temporal accuracy of two. Notably, our approach offers the advantage of directly tackling singular biharmonic problems without the need for discretizing boundary conditions or incorporating fictitious points. It demonstrates unconditional stability when tested on fourth-order problems and outperforms previous methods, as evidenced by comparative analyses. Additionally, we present 2D and 3D plots illustrating numerical solutions for different benchmark scenarios, including the depiction of the chaotic nature of the Kuramoto-Sivashinsky equation under Gaussian initial conditions at various time levels.
Statistical analysis of Cu content effects on structural properties in CuZr metallic glasses
Authors: Amigo Nicolás
Published: September 2024

This study examines the effects of casting conditions on the structural properties of CuZr metallic glasses (MGs) using molecular dynamics simulations. The influence of Cu content on various structural properties was explored, finding significant power-law relationships that indicate increased Cu promotes the formation of icosahedra-like structures and enhances the population of solid-like polyhedra. In contrast, the clustering coefficient, reflecting solid-like connectivity, showed a linear relationship with Cu content, revealing that while Cu increases solid-like structures, their connectivity does not scale proportionally. No significant correlations were found for sample volume, cooling rate, or temperature within the studied ranges. This study highlights the utility of statistical analysis in elucidating material property relationships, contrasting with the less interpretable nature of machine learning models. The findings provide valuable insights into the role of Cu content in MGs and demonstrate the importance of traditional statistical approaches for material characterization.
Achieving beyond 30% efficiency for hole-transport-layer-free CsSnI3 perovskite solar cell: a comprehensive simulation study
Authors: Ullah Saad , ul Ain Qurat , Qamar Samina , Khan Firoz , Khan Mohd Taukeer
Published: September 2024

In recent years, the growing significance of lead-free CsSnI3 perovskite can be credited to its outstanding optoelectronic properties and environmentally friendly nature. Nevertheless, the photovoltaic potential of CsSnI3 is limited due to challenges in achieving defect-free device structures. The current study thoroughly analyzed the performance of CsSnI3-based perovskite solar cells (PSCs) using the SCAPS-1D software. An in-depth investigation was performed on multiple physical parameters, including the thickness of perovskites layer, acceptor density (NA), operating temperature, defect densities, shunt resistance (RSh) and series resistance (RS). This comprehensive study aimed to identify the optimal device configuration that yields the highest power conversion efficiency (PCE) for the hole-transport-layer (HTL)-free CsSnI3-based PSCs. The obtained results confirmed that it is crucial to decrease the number of defects (Nt) at the perovskites/electron transport layer (ETL) interface to improve the efficiency of CsSnI3-based PSCs. The optimized device demonstrated exceptional performance, achieving an open-circuit voltage (VOC) of 1.12 V, a fill factor (FF) of 85.08%, a short-circuit current density (JSC) of 33.29 mA cm−2 and an efficiency of 31.87%. This high efficiency simulated result provide valuable insights into the design of high-performance CsSnI3-based PSCs, paving the way for potential breakthroughs in cost-effective and eco-friendly solar energy technologies.
Millimeter wave frequency generation based on variations in coupling coefficients of a silicon add-drop microring resonator
Authors: Katti Rohan , Prince Shanthi
Published: September 2024

A microwave photonic system with silicon add-drop microring resonator as the core photonic device is analyzed for microwave/millimeter wave frequency generation. The primary concept of the proposed study relies on varying the coupling coefficients of the silicon add-drop microring resonator. Unequal coupling coefficients between the ring cavity and bus waveguides are one of the parameters which are responsible for generating second, third order sidebands in the radio frequency spectrum generated at the photodetector. Another parameter of interest is the phase difference between the two radio frequency signals which are fed to the Mach–Zehnder modulators of the proposed system. A 1 GHz sinusoidal signal with 1V peak-to-peak amplitude results in a third order sideband generation whose frequency corresponds to 3 GHz. The coupling coefficients in this case are 0.2 and 0.8, between ring cavity, top and bottom waveguides respectively. It is also observed that, phase difference of 90◦ between the input radio frequency signals results in highest power of the third order sideband generated in the output radio frequency spectrum whose frequency corresponds to the multiple of input radio frequency.
Axion dark matter with explicit Peccei-Quinn symmetry breaking in the axiverse
Authors: Li Hai-Jun
Published: September 2024

It was shown that the required high quality of the Peccei-Quinn (PQ) symmetry can be a natural outcome of the multiple QCD axions model.
In the axiverse, a hypothetical mass mixing between the QCD axions and axion-like particles (ALPs) can occur, which leads to an interesting phenomenon called the level crossing.
In this paper, we investigate this mass mixing between one QCD axion and one ALP with the explicit PQ symmetry breaking in the early Universe.
The dynamics of the axions and their cosmological evolutions when the level crossing occurs in this scenario are studied in detail.
We show the evolution of the mass eigenvalues and the mass mixing angle.
Then we check the condition for energy adiabatic transition with the corresponding parameter set.
Finally, we estimate the relic density of the QCD axion and ALP dark matter through the misalignment mechanism.
We find that, the QCD axion relic density can be suppressed, while the ALP relic density can be enhanced.
The level crossing in our scenario may have some cosmological implications, such as the axion domain walls formation, the nano-Hertz gravitational waves emission, and also the primordial black holes formation.
Group frames via magic states with applications to SIC-POVMs and MUBs
Authors: Feng Lingxuan , Luo Shunlong
Published: September 2024

We connect magic (non-stabilizer) states, symmetric informationally complete positive operator valued measures (SIC-POVMs), and mutually unbiased bases (MUBs) in the context of group frames, and study their interplay. Magic states are quantum resources in the stabilizer formalism of quantum computation. SIC-POVMs and MUBs are fundamental structures in quantum information theory with many applications in quantum foundations, quantum state tomography, and quantum cryptography, etc. In this work, we study group frames constructed from some prominent magic states, and further investigate their applications. Our method exploits the orbit of discrete Heisenberg–Weyl group acting on an initial fiducial state. We quantify the distance of the group frames from SIC-POVMs and MUBs, respectively. As a simple corollary, we reproduce a complete family of MUBs of any prime dimensional system by introducing the concept of MUB fiducial states, analogous to the well-known SIC-POVM fiducial states. We present an intuitive and direct construction of MUB fiducial states via quantum T-gates, and demonstrate that for the qubit system, there are twelve MUB fiducial states, which coincide with the H-type magic states. We compare MUB fiducial states and SIC-POVM fiducial states from the perspective of magic resource for stabilizer quantum computation. We further pose the challenging issue of identifying all MUB fiducial states in general dimensions.
Characterization of highly radiating nitrogen-seeded H-mode plasmas in unfavorable BT at ASDEX Upgrade
Authors: Chen L. , Wolfrum E. , Pan O. , Kurzan B. , Bernert M. , Brida D. , Cavedon M. , Dux R. , Fischer R. , Griener M. , Grover O. , Plank U. , Stieglitz D. , Zito A. ,   the ASDEX Upgrade Team
Published: September 2024

The highly radiating nitrogen-seeded H-mode plasmas in unfavorable BT
has been characterized in the ASDEX Upgrade tokamak (AUG). Three levels of nitrogen puffing rates have been injected into a fully detached H-mode plasma, which is run in lower single null configuration with the ion

B
×
∇
B

drift away from the X-point. A cold (

∼

1
−
2

eV) highly radiating (

∼

13.0

MW

m

−
3

) region forms close to the X-point immediately after nitrogen seeding, as evidenced by measurements of the divertor Thomson scattering (DTS) and the two-dimensional bolometry reconstructions. In addition, the radiator moves further upwards above the X-point along the separatrix at the high-field side (HFS) with increasing nitrogen puffing rates, as evidenced by the Absolute eXtended UltraViolet (AXUV) measurements. The formation of the highly radiating regime is closely correlated to the modifications of the divertor plasma conditions. Along the line of sight of the DTS measurement, the electron temperature reduces down to a few eV, which initials near the X-point and further extends to the HFS scrape-off layer (SOL) simultaneously with the upward movement of the radiator, however, the electron temperature sustains (

∼

30
−
50

eV) at the low-field side (LFS) SOL with slightly decreased electron density. The highly radiating regime shows LFS/HFS divertor asymmetry, in contrast to that for H-mode plasmas in favorable BT
, suggesting that the drifts play an important role for the formation of the highly radiating X-point regime at AUG. The neutral particle flux increases significantly (factor of

∼

2

) in the private flux region, while it increases slightly (

<

20
%

) in the main chamber, thus suggesting an enhanced sub-divertor neutral compression with the formation of the highly radiating regime. Furthermore, a degradation of the pedestal electron density was observed with an enhancement of the electron temperature further inside the pedestal, and complete divertor detachment was achieved by nitrogen seeding with sustained plasma confinement. Finally, particle sources and flow patterns of deuterium and nitrogen ions have been analyzed by SOLPS-ITER modelling, confirming that the

E

×

B

drift plays an important role for the formation of the highly radiating regime in unfavorable BT
at AUG.
How megacities can achieve carbon peak through structural adjustments: an input–output perspective
Authors: Yang Yang , Wang Yiqi , Ji Junping , Wang Dong , Huang Qisheng , He Daojing
Published: September 2024

There is still a huge gap between the emissions pathways of megacities and the pathways to meeting the targets set by the Paris agreement. Compared with technological emission reductions, structural emission reduction can provide cities with more stable and sustainable carbon-peaking solutions. This study constructs a scenario-based input–output optimization model, adopting a novel carbon emission accounting method for purchased electricity that considers shared responsibility, and systematically evaluates the decarbonization paths of megacities and their impacts on economic growth, energy consumption, and carbon emissions. The results show that (a) through industry substitution and manufacturing restructuring, Shenzhen is projected to peak at 57.68 MtCO2 emissions in 2026, with a 10.57% energy and a 19.55% carbon reduction by 2030. (b) Shenzhen can achieve its carbon emission peak target through the energy transition while accepting a loss of 0.97%–3.23% of GDP, requiring the maximum economic concession of 16.45% from the transportation sector (S10) in the early stage of transformation, while 12.24% from the extractive industry (S2) in the later stage. (c) The comprehensive structure adjustment proved to be more effective than other mitigation approaches, capable of achieving high-quality economic growth of 6.4% during the study period while reaching a peak target of 53.55 million tons of CO2 by 2026. (d) The emission reduction effect of the power sector was the most significant among all the scenarios, with emission reduction rates between 6.26% and 35.63%, and the cumulative emission reduction potential reached 38.1–110.6 MtCO2. The priority for emission reduction in the power sector is the coal phase-out plan, which is essential for achieving these significant reductions. This study provides an important reference for megacities facing similar challenges, especially those in developing countries, to achieve a stable and sustainable carbon peak pathway through structural adjustment.
Hardening mechanism and thermal-solid coupling model of laminar plasma surface hardening of 65 Mn steel
Authors: CAO 曹 Xiuquan 修全 , WANG 王 Lin 林 , XU 徐 Haoming 浩铭 , HU 胡 Guangzhong 光忠 , LI 李 Chao 超
Published: September 2024

In the present work, the laminar plasma surface hardening method is employed to enhance the service life of metal components fabricated from 65 Mn steel. The mechanical and wear behaviors of the laminar plasma surface hardened 65 Mn steel were analyzed. The martensite transition transformation of the temperature of the laminar plasma-hardened 65 ferrite Mn steel was determined by a thermal-solid coupling model. Based on the orthogonal experimental results, the optimal hardening parameters were confirmed. The scanning velocity, quenching distance and arc current are 130 mm/min, 50 mm and 120 A, respectively. The pearlites and ferrites are transformed into martensites in the hardened zone, while the ratio of martensite in the heat-affected zone decreases with the increase in the hardening depth. Compared to the untreated 65 Mn steel, the average hardness increases from 220 HV0.2 to 920 HV0.2 in the hardened zone and the corresponding absorbed power increases from 118.7 J to 175.5 J. At the same time, the average coefficient of friction (COF) decreases from 0.763 to 0.546, and the wear rate decreases from 5.39×10−6 mm3/(N·m) to 2.95×10−6 mm3/(N·m), indicating that the wear resistance of 65 Mn steel could be significantly improved by using laminar surface hardening. With the same hardening parameters, the depth and width of the hardened zone predicted by the thermal-solid coupling model are 1.85 mm and 11.20 mm, respectively, which are in accordance with the experimental results; depth is 1.83 mm and width is 11.15 mm. In addition, the predicted hardness distributions of the simulation model are in accordance with the experimental results. These results indicate that the simulation model could effectively predict the microstructure characteristics of 65 Mn steel.
Insulating behaviour in room temperature rhombohedral LiNiO2 cathodes is driven by dynamic correlation
Authors: Banerjee H , Aichhorn M , Grey C P , Morris A J
Published: September 2024

Inspired by the experimental finding of a paramagnetic insulating state in rhombohedral LiNiO2, a lithium-ion battery cathode of great interest, we calculate the electronic, magnetic, and optical properties of LiNiO2 employing a range of single-particle and many-body methods. Within density-functional theory (DFT) using the generalized-gradient approximation (GGA), meta-GGA, and hybrid functionals, we obtain a ferromagnetic half-metallic ground state for rhombohedral LiNiO2, as has been seen previously. Self-consistent GW calculations including self-interaction corrections beyond DFT for various flavours show an electronic band gap albeit with a small quasiparticle peak at the Fermi energy. Moving beyond this, room temperature state-of-the-art dynamical mean-field theory (DMFT) calculations on rhombohedral LiNiO2 show for the first time a gap of combined Mott and charge-transfer character. The paramagnetic insulating state has a band gap of ~0.6 eV, in excellent agreement with experiments and is in sharp contrast to DFT calculations that require the presence of an extra structural symmetry breaking in the form of Jahn–Teller distortions to open a gap. We observe Ni to be in a +2 state in a d
8L configuration, with a charge-transfer ligand hole in O p, and identify the ligand hole state from the DMFT DOS. We further show that whereas DFT shows the presence of an unphysical metallic Drude peak in the optical absorption spectra, DMFT calculations capture the correct form of the optical absorption spectra, and have an excellent match with the calculated band gap as well. Our results clarify that at room temperature, it is the charge transfer gap with a Mott character that causes rhombohedral LiNiO2’s insulating nature; a structural distortion is not required.
Experimental investigation into friction stir welding of AA6061-T6 and magnesium AZ31B alloy using copper backing plate
Authors: Maniyar D G , Gadakh V S , Badheka V J , Jagtap K B , Mane S S , Dethe S M
Published: September 2024

Aluminium-magnesium alloys are lightweight and possess superior properties, making them ideal for applications in aerospace, railway, automotive, and marine structures. However, these alloys are challenging to fabricate using traditional fusion welding due to various metallurgical issues. This study investigates the feasibility of joining 3 mm thick dissimilar alloys of aluminium AA6061-T6 and magnesium AZ31B using the friction stir welding (FSW) process with copper as a backing plate. The effects of FSW process parameters, including tool rotational speed (380, 545, 765 rpm), weld speed (20, 31.5, 50 mm min−1), and tilt angle (1°, 2°, 3°), on tensile properties were examined using Taguchi-based grey relational analysis. Temperatures were recorded during the FSW process under different conditions on both sides of the joint. The highest tensile strength of 130.72 MPa, with a joint efficiency of 67.85%, was achieved at a tool rotational speed of 765 rpm, a welding speed of 50 mm min−1, and a tilt angle of 2°. Analysis of variance (ANOVA) for the grey relational grade indicated that the tilt angle had the highest percentage contribution of 43.60%. This study demonstrates the significant influence of FSW parameters on the mechanical properties of aluminium-magnesium joints and highlights the optimal conditions for achieving high joint strength and efficiency.
Equivariant tensor network potentials
Authors: Hodapp M , Shapeev A
Published: September 2024

Machine-learning interatomic potentials (MLIPs) have made a significant contribution to the recent progress in the fields of computational materials and chemistry due to the MLIPs’ ability of accurately approximating energy landscapes of quantum-mechanical models while being orders of magnitude more computationally efficient. However, the computational cost and number of parameters of many state-of-the-art MLIPs increases exponentially with the number of atomic features. Tensor (non-neural) networks, based on low-rank representations of high-dimensional tensors, have been a way to reduce the number of parameters in approximating multidimensional functions, however, it is often not easy to encode the model symmetries into them. In this work we develop a formalism for rank-efficient equivariant tensor networks (ETNs), i.e. tensor networks that remain invariant under actions of SO(3) upon contraction. All the key algorithms of tensor networks like orthogonalization of cores and DMRG-based algorithms carry over to our equivariant case. Moreover, we show that many elements of modern neural network architectures like message passing, pulling, or attention mechanisms, can in some form be implemented into the ETNs. Based on ETNs, we develop a new class of polynomial-based MLIPs that demonstrate superior performance over existing MLIPs for multicomponent systems.
Uncovering obscured phonon dynamics from powder inelastic neutron scattering using machine learning
Authors: Su Yaokun , Li Chen
Published: September 2024

The study of phonon dynamics is pivotal for understanding material properties, yet it faces challenges due to the irreversible information loss inherent in powder inelastic neutron scattering spectra and the limitations of traditional analysis methods. In this study, we present a machine learning framework designed to reveal obscured phonon dynamics from powder spectra. Using a variational autoencoder, we obtain a disentangled latent representation of spectra and successfully extract force constants for reconstructing phonon dispersions. Notably, our model demonstrates effective applicability to experimental data even when trained exclusively on physics-based simulations. The fine-tuning with experimental spectra further mitigates issues arising from domain shift. Analysis of latent space underscores the model’s versatility and generalizability, affirming its suitability for complex system applications. Furthermore, our framework’s two-stage design is promising for developing a universal pre-trained feature extractor. This approach has the potential to revolutionize neutron measurements of phonon dynamics, offering researchers a potent tool to decipher intricate spectra and gain valuable insights into the intrinsic physics of materials.
Qualitative analysis of hydroponic container farm adoption, use, and benefits in the U.S.
Authors: Kaminski Alexa G , Babbitt Callie W
Published: September 2024

The impacts of climate change, population growth, and resource constraints on conventional agriculture have sparked interest in controlled environment agriculture (CEA) technology. The hydroponic container farm (HCF) is a type of small-scale CEA infrastructure increasingly being adopted by cities, businesses, and nonprofits. Yet there is still significant uncertainty about HCF use, potential value to the food system, and broader sustainability benefits and tradeoffs. This research uses semi-structured interviews with farmers operating HCFs across the U.S. and grounded theory analysis to characterize HCF use, outcomes, benefits, and challenges. Results show that HCFs contribute direct benefits as food system infrastructure through food production, particularly in urban regions where conventional agriculture is infeasible, but also provide indirect benefits through education, workforce development, and broader social impact. Despite wide differences in the ways organizations use HCFs, we identified universal factors that moderate successful outcomes, including municipal zoning and permitting regulations, relationships between the HCF farmer and partners, the business model under which the HCF operates, and the design and cost of hydroponic technology. This study begins to characterize the social and economic tradeoffs that HCFs generate and provides use case data for future quantifications of environmental impact.
Coupling human dynamics with the physics of climate: a path towards Human Earth Systems Models
Authors: Tapiador Francisco J , Navarro Andrés
Published: September 2024

Climate models are fundamental tools for the study of global change. They are used not only to test scientific hypotheses about the physical processes operating in planetary atmospheres, but also to advise society about expected changes in the climate of our planet. Current Earth System Models have begun to incorporate biological, chemical and geological processes (biogeochemical cycles, water chemistry) as feedback between the surface and the atmosphere. However, due to the many challenges involved, the integration of ‘human dynamics’ remains to be fully addressed. This perspective outlines a path towards two-way feedback Human Earth Systems Models. Major challenges in the plan include how to deal with the uncertainty inherent in human behavior and our interaction with the environment, the limits of predictability, and the scale of computational resources required to model human behavior with sufficient accuracy (i.e. close to observed measurements) and precision (i.e. with low dispersion). This paper provides a roadmap towards a tool that could revolutionize Earth system modeling by fully integrating the physical and human systems.
Health impacts of excessive heat in Multnomah County, OR, 2021
Authors: Haggerty Brendon , DiLeo Kimberly , Nonnamaker Max , Thompson Jason , Walters Jaime
Published: September 2024

Human-induced climate change is leading to increased extreme weather events, such as the heat dome that occurred in Multnomah County, OR, in June 2021. Certain groups are at increased risk from excessive heat events, such as the very young and very old, persons without stable housing, and persons with certain health comorbidities. Our review of three data sources (deaths, hospitalizations, and emergency department visits) showed large increases in all three measures in the summer of 2021. Further, two-thirds of identified heat deaths occurred in or near neighborhoods that ranked among the most vulnerable to extreme heat. Despite thoughtful planning, a recently updated heat response plan, and an unprecedented mobilization of resources, we documented severe health impacts due to this heat event. We recommend that local health jurisdictions and emergency responders increase readiness for such events by interrogating existing plans and tailoring them not to events of expected severity, but to a worst case scenario that exceeds historic experiences.
FHOD-1 and profilin protect sarcomeres against contraction-induced deformation> in C. elegans
Authors: Kimmich Michael J. , Sundaramurthy Sumana , Geary Meaghan A. , Lesanpezeshki Leila , Yingling Curtis V. , Vanapalli Siva A. , Littlefield Ryan S. , Pruyne David
Published: September 2024

Formin HOmology Domain 2-containing (FHOD) proteins are a subfamily of actin-organizing formins important for striated muscle development in many animals. We showed previously that absence of the sole FHOD protein, FHOD-1, from Caenorhabditis elegans results in thin body wall muscles with misshapen dense bodies that serve as sarcomere Z-lines. We demonstrate here that mutations predicted to specifically disrupt actin polymerization by FHOD-1 similarly disrupt muscle development, and that FHOD-1 cooperates with profilin PFN-3 for dense body morphogenesis, and with profilins PFN-2 and PFN-3 to promote body wall muscle growth. We further demonstrate that dense bodies in worms lacking FHOD-1 or PFN-2/PFN-3 are less stable than in wild-type animals, having a higher proportion of dynamic protein, and becoming distorted by prolonged muscle contraction. We also observe accumulation of actin and actin depolymerization factor/cofilin homologue UNC-60B in body wall muscle of these mutants. Such accumulations may indicate targeted disassembly of thin filaments dislodged from unstable dense bodies, possibly accounting for the abnormally slow growth and reduced body wall muscle strength in fhod-1 mutants. Overall, these results implicate FHOD protein–mediated actin assembly in forming stable sarcomere Z-lines, and identify profilin as a new contributor to FHOD activity in striated muscle development.
Big1 is a newly identified autophagy regulator that is critical for a fully functional V-ATPase
Authors: Lei Yuchen , Yang Ying , Zhang Zhihai , Zhang Ruoxi , Song Xinxin , Malek Sami N. , Tang Daolin , Klionsky Daniel J.
Published: September 2024

The vacuolar-type H+-translocating ATPase (V-ATPase) is the major proton pump for intraorganellar acidification. Therefore, the integrity of the V-ATPase is closely associated with cellular homeostasis, and mutations in genes encoding V-ATPase components and assembly factors have been reported in certain types of diseases. For instance, the recurrent mutations of ATP6AP1, a gene encoding a V-ATPase accessory protein, have been associated with cancers and immunodeficiency. With the aim of studying V-ATPase–related mutations using the yeast model system, we report that Big1 is another homologue of ATP6AP1 in yeast cells, and we characterize the role of Big1 in maintaining a fully functional V-ATPase. In addition to its role in acidifying the vacuole or lysosome, our data support the concept that the V-ATPase may function as part of a signaling pathway to regulate macroautophagy/autophagy through a mechanism that is independent from Tor/MTOR.
The Fragile Ground of New England, 1638–1755
Authors: Brickhouse Anna
Published: September 2024

Puritan elites interpreted the seismic events of their moment by writing global earthquake histories that could accommodate an emerging culture of mastery and slavery sanctified by the idea of just war. Early New England earthquakes also reminded Puritans that those who had already inhabited the land long before their arrival understood earthquake in the New World in ways that they could not. Earthquake struck at the tenuously settled ground of colonial occupation and land enclosure; it emblematized the continual problem of settler security and the specific threat of Native agency. The Black and Indigenous specters who appeared during the Salem witch trials always had earthquake at their fingertips; earthquake thus required interpretive vigilance on the part of those with most power, lest other meanings take hold. This earthquake vigilance introduced a settler colonial Enlightenment: a culture of frantic knowledge production that had no confidence in the stability of the earth or in the security of settler polities and psyches.
The Undeceiving Earth
Authors: Brickhouse Anna
Published: September 2024

This chapter explores the writings of Herman Melville, whose entire oeuvre grapples with the southernizing geographies of Western theology and philosophy. Mardi is read as an allegory of global-colonial modernity that continually re-enacts the foundational Columbian narrative of La Navidad. The chapter then examines “The Town-Ho’s Story” in Moby-Dick for its self-consciously located diegesis set in Peru, the staging ground for an earthquake-whale’s assault on the colonial foundations of modern Western philosophy. Melville returned to this violent foundation in The Piazza Tales. The conclusion takes up Melville’s later writings, from The Confidence-Man to Timoleon, to show how the rending of the earth continues after the Civil War to foreground the predatory basis of optimism and the racial and geographic underpinnings of theodicy in a global-colonial world. Melville takes earthquake to be a quintessential figure for undeception, antithetical to the nineteenth-century invention of US-America as a denial of ongoing forms of conquest and coloniality in the here and now.