bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring torsional conformer space with physical prior mean function-driven meta-Gaussian processes
Authors: Teng Chong , Huang Daniel , Donahue Elizabeth , Bao Junwei Lucas
Published: December 2023

We present a novel approach for systematically exploring the conformational space of small molecules with multiple internal torsions. Identifying unique conformers through a systematic conformational search is important for obtaining accurate thermodynamic functions (e.g., free energy), encompassing contributions from the ensemble of all local minima. Traditional geometry optimizers focus on one structure at a time, lacking transferability from the local potential-energy surface (PES) around a specific minimum to optimize other conformers. In this work, we introduce a physics-driven meta-Gaussian processes (meta-GPs) method that not only enables efficient exploration of target PES for locating local minima but, critically, incorporates physical surrogates that can be applied universally across the optimization of all conformers of the same molecule. Meta-GPs construct surrogate PESs based on the optimization history of prior conformers, dynamically selecting the most suitable prior mean function (representing prior knowledge in Bayesian learning) as a function of the optimization progress. We systematically benchmarked the performance of multiple GP variants for brute-force conformational search of amino acids. Our findings highlight the superior performance of meta-GPs in terms of efficiency, comprehensiveness of conformer discovery, and the distribution of conformers compared to conventional non-surrogate optimizers and other non-meta-GPs. Furthermore, we demonstrate that by concurrently optimizing, training GPs on the fly, and learning PESs, meta-GPs exhibit the capacity to generate high-quality PESs in the torsional space without extensive training data. This represents a promising avenue for physics-based transfer learning via meta-GPs with adaptive priors in exploring torsional conformer space.
Improving performances of ultra-small size (1–20
μ
m) InGaN red micro-LEDs by growing on freestanding GaN substrates
Authors: Yu Luming , Hao Zhibiao , Luo Yi , Sun Changzheng , Xiong Bing , Han Yanjun , Wang Jian , Li Hongtao , Gan Lin , Jiang Yang , Chen Hong , Wang Lai
Published: December 2023

The ultra-small size InGaN red micro-LED has attracted a lot of research interest for AR micro-display applications. However, it still faces the challenge of maintaining the emission wavelength and efficiency that meet the needs of micro-display in small size and high current density. Here, we demonstrate 1–20 μm InGaN red micro-LEDs based on freestanding GaN substrates, showing enhanced indium incorporation compared with those grown on traditional sapphire substrates. For the 1 μm devices, an external quantum efficiency (on-wafer) of 0.86% and a wavelength of 613.6 nm are achieved at a current density of 50 A/cm2. In addition, the emission uniformity of 1 μm array grown on GaN substrates is significantly superior to that grown on sapphire substrates. These results indicate that freestanding GaN substrates are benefits for improving performance of red InGaN micro-LEDs.
Constructions of the soliton solutions to coupled nonlinear Schrödinger equation with advanced mathematical techniques
Authors: Alharbi Taghread Ghannam , Alharbi Abdulghani
Published: December 2023

In our research paper, we explore the application of mathematical techniques, both analytical and numerical, to solve the coupled nonlinear Schrödinger equation. To obtain accurate solutions, we use the improved, modified, extended tanh-function method. By breaking down the Schrödinger equation into real and imaginary components, we derive four interconnected equations. We analyze these equations using the generalized tanh method to find precise solutions. This set of equations is of great importance in quantum mechanics and helps us understand the behavior of quantum systems. We provide an analytical and numerical solution using the implicit finite difference. Our method is second-order in both space and time, and we have verified its stability through von Neumann’s stability analysis.
Features of laminar separation bubble subjected to varying adverse pressure gradients
Authors: Kumar Ravi , Sarkar S.
Published: December 2023

This article describes the spatial development of a laminar separation bubble (LSB), its transition, and eventual breakdown under the influence of adverse pressure gradients (APGs) similar to those experienced by low-pressure turbine blades. The investigation combines a comprehensive experimental approach with a well-resolved large eddy simulation (LES). The streamwise pressure gradients were varied by manipulating the upper wall within the test section. The Reynolds number (Re), based on the plate length and inlet velocity, was 0.2 × 106 with a freestream turbulence intensity of 1.02%. The particle image velocimetry (PIV) and hotwire data were used to illustrate the vortex dynamics, growth of perturbations, and intermittency. The onset and end of transition progressively shift upstream, resulting in a reduction of the laminar shear layer length and bubble length with increasing APG. Interestingly, the flow features exhibit self-similarity in velocity profiles and the growth rate of velocity fluctuations when normalized against the bubble length. The formation of two-dimensional Kelvin–Helmholtz (K–H) rolls is apparent in the beginning, resulting in the selective amplification of frequency and exponential growth of fluctuations. Linear stability theory explains the most amplified frequency and phase speed of convective vortices, apart from the growth of disturbances. Analysis of LES data reveals intricate inviscid–viscous interactions that trigger shear layer breakdown. In brief, evolving perturbations within the braid region of vortices in the latter half interact with the advecting K–H rolls, culminating in the breakdown and the onset of turbulent flow downstream.
How the dynamics of attachment to the substrate influence stress in metal halide perovskites
Authors: McAndrews Gabriel R. , Guo Boyu , Morales Daniel A. , Amassian Aram , McGehee Michael D.
Published: December 2023

Metal halide perovskites have the potential to contribute to renewable energy needs as a high efficiency, low-cost alternative for photovoltaics. Initial power conversion efficiencies are superb, but improvements to the operational stability of perovskites are needed to enable extensive deployment. Mechanical stress is an important, but often misunderstood factor impacting chemical degradation and reliability during thermal cycling of perovskites. In this manuscript, we find that a commonly used equation based on the coefficient of thermal expansion (CTE) mismatch between perovskite and substrate fails to accurately predict residual stress following solution-based film formation. For example, despite similar CTEs there is a 60 MPa stress difference between narrow bandgap “SnPb perovskite” Cs0.25FA0.75Sn0.5Pb0.5I3 and “triple cation perovskite” Cs0.05MA0.16FA0.79Pb(I0.83Br0.17)3. A combination of in situ absorbance and substrate curvature measurements are used to demonstrate that partial attachment prior to the anneal can reduce residual stress and explain wide stress variations in perovskites.
Effect of dilute nitride GaNAs quantum well thickness on spin amplification dynamics of tunnel-coupled InAs quantum dots
Authors: Sato Shino , Hiura Satoshi , Takayama Junichi , Murayama Akihiro
Published: December 2023

Electron spin dynamics of dilute nitride GaNAs quantum well (QW)-InAs quantum dots (QDs) tunnel-coupled structures having different QW thicknesses were studied via circularly polarized time-resolved photoluminescence. The rate equation fitting considering a capture of QD electron spins by the GaNAs localized states via tunnel transfer revealed that the spin amplification dynamics of the QDs depended on the QW thickness. For the QW thickness of 5 nm, although the temporal amplification of QD electron spin polarization was slow owing to the weak wavefunction coupling between the QW and QD, the long duration of high electron spin polarization was observed because of the suppressed capture of QD majority spins relative to the efficient removal of QD minority spins. When the QW thickness increased from 5 to 20 nm, the strong spin filtering in GaNAs and strong wavefunction coupling led to the fast amplification of QD electron spin polarization with high initial spin polarization. However, the spin polarization rapidly decays after the amplification owing to the removal of both QD majority and minority spins, originating from many effective localized states. These results indicate that the time-dependent QD electron spin polarization and the resultant spin amplification can be widely tuned by changing the thickness of the tunnel-coupled GaNAs QW.
Light antiproton one-electron quasi-molecular ions within the relativistic A-DKB method
Authors: Anikin A. , Danilov A. , Glazov D. , Kotov A. , Solovyev D.
Published: December 2023

In the present work, two quasi-molecular compounds each involving one antiproton and one electron (p̄), He+−p̄ and H−p̄, are investigated. Using completely relativistic calculations within the finite-basis method adapted to systems with axial symmetry, the adiabatic potential curves are constructed by numerically solving the two-center Dirac equation. The binding energies of electron are obtained as a function of the inter-nuclear distance and compared with the corresponding nonrelativistic values and relativistic leading-order corrections calculated in the framework of other approaches. A semantic analysis of antiproton quasi-molecular ions with compounds containing a proton (p) instead of an antiproton is given. The advantages of the A-DKB method are demonstrated.
Cross-plane thermal transport in layered materials
Authors: Gokhale Amey G. , Jain Ankit
Published: December 2023

The cross-plane (across-layers) phonon thermal transport of five diverse, layered semiconductors is investigated by accounting for higher-order four-phonon scattering, phonon renormalization, and multi-channel thermal transport. For materials having relatively large cross-plane thermal conductivity (AlB6, MoS2, and MoSi2N4), phonons contributing to cross-plane conductivity have an order of magnitude larger mean free path than that for the basal-plane thermal transport, whereas the opposite effect is observed for materials with low thermal conductivity (MoO3 and KCuSe). The contribution from the wave-like coherent transport channel is less than 5% in all considered materials. Our work unravels the contrasting role of nanostructuring on the basal- vs cross-plane thermal conductivity of low and high thermal conductivity layered materials.
Applications of fluid dynamics and mechanics of continua in forensics
Authors: Yarin Alexander L.
Published: December 2023

Here, an overview is given of a collection of works published by Physics of Fluids under an umbrella-title Flow and Forensics. These works span the two fields, which currently coexist without too much interaction, namely, fluid mechanics and forensic science. Nevertheless, both fields reveal mutual interest for quite some time. The present work demonstrates that not only a tangential interaction, but a wide mutual polymer-like reptation might be beneficial for both fields. The present set of works already demonstrates that sub-fields of fluid mechanics, such as multi-phase flows, gas dynamics, and rheology, fluid mechanical topics, such as drops and vortices, and tools, such as de Laval nozzle, are not alien at all to forensic science subjects and could be beneficial for them. In its turn, forensic science can enrich fluid mechanics by such subjects as blood pattern analysis, blood and brain spatter analysis, prediction of the blood spatter origin, and delineation of a staged suicide (a homicide) from a real one.
The TLR2/TLR6 ligand FSL-1 mitigates radiation-induced hematopoietic injury in mice and nonhuman primates
Authors: Brickey W. June , Caudell David L. , Macintyre Andrew N. , Olson John D. , Dai Yanwan , Li Sirui , Dugan Gregory O. , Bourland J. Daniel , O’Donnell Lisa M. , Tooze Janet A. , Huang Guannan , Yang Shuangshuang , Guo Hao , French Matthew N. , Schorzman Allison N. , Zamboni William C. , Sempowski Gregory D. , Li Zhiguo , Owzar Kouros , Chao Nelson J. , Cline J. Mark , Ting Jenny P. Y.
Published: December 2023

Thrombocytopenia, hemorrhage, anemia, and infection are life-threatening issues following accidental or intentional radiation exposure. Since few therapeutics are available, safe and efficacious small molecules to mitigate radiation-induced injury need to be developed. Our previous study showed the synthetic TLR2/TLR6 ligand fibroblast stimulating lipopeptide (FSL-1) prolonged survival and provided MyD88-dependent mitigation of hematopoietic acute radiation syndrome (H-ARS) in mice. Although mice and humans differ in TLR number, expression, and function, nonhuman primate (NHP) TLRs are like those of humans; therefore, studying both animal models is critical for drug development. The objectives of this study were to determine the efficacy of FSL-1 on hematopoietic recovery in small and large animal models subjected to sublethal total body irradiation and investigate its mechanism of action. In mice, we demonstrate a lack of adverse effects, an easy route of delivery (subcutaneous) and efficacy in promoting hematopoietic progenitor cell proliferation by FSL-1. NHP given radiation, followed a day later with a single subcutaneous administration of FSL-1, displayed no adversity but showed elevated hematopoietic cells. Our analyses revealed that FSL-1 promoted red blood cell development and induced soluble effectors following radiation exposure. Cytologic analysis of bone marrow aspirates revealed a striking enhancement of mononuclear progenitor cells in FSL-1-treated NHP. Combining the efficacy of FSL-1 in promoting hematopoietic cell recovery with the lack of adverse effects induced by a single administration supports the application of FSL-1 as a viable countermeasure against H-ARS.
Triggered lattice-oxygen oxidation with active-site generation and self-termination of surface reconstruction during water oxidation
Authors: Wei Yicheng , Hu Yang , Da Pengfei , Weng Zheng , Xi Pinxian , Yan Chun-Hua
Published: December 2023

To master the activation law and mechanism of surface lattice oxygen for the oxygen evolution reaction (OER) is critical for the development of efficient water electrolysis. Herein, we propose a strategy for triggering lattice-oxygen oxidation and enabling non-concerted proton–electron transfers during OER conditions by substituting Al in La
0.3
Sr
0.7
CoO
3−

δ

. According to our experimental data and density functional theory calculations, the substitution of Al can have a dual effect of promoting surface reconstruction into active Co oxyhydroxides and activating deprotonation on the reconstructed oxyhydroxide, inducing negatively charged oxygen as an active site. This leads to a significant improvement in the OER activity. Additionally, Al dopants facilitate the preoxidation of active cobalt metal, which introduces great structural flexibility due to elevated O 2
p
levels. As OER progresses, the accumulation of oxygen vacancies and lattice-oxygen oxidation on the catalyst surface leads to the termination of Al
3+
leaching, thereby preventing further reconstruction. We have demonstrated a promising approach to achieving tunable electrochemical reconstruction by optimizing the electronic structure and gained a fundamental understanding of the activation mechanism of surface oxygen sites.
Dynamic micromechanical measurement of the flexural modulus of micrometre-sized diameter single natural fibres using a vibrating microcantilever technique
Authors: Reda Ali , Dargent Thomas , Arscott Steve
Published: December 2023

The dynamic response of a structure is a manifestation of its inherent characteristics, including material density, mechanical modulus, thermo- and viscoelastic properties, and geometric properties. Together, these factors influence how the material behaves in dynamic scenarios, dictating its damping properties and behaviour under varying forces. In this study we present a novel approach to accurately determine the flexural (bending) modulus of microscopic diameter natural fibres (flax) using microcantilever vibration analysis. Traditionally, the characterisation of the mechanical properties of fibres has relied on macroscopic methods such as tensile testing, which often results in high scatter in measurement data; furthermore, tensile testing does not accurately represent microscale or dynamic conditions and can be complex in terms of sample preparation and loading. To address this, we have developed a microscale technique involving the fabrication of microcantilevers using flat polypropylene support chips, inspired by microelectromechanical systems approaches. Our method provides a refined method for accurately characterising the mechanical modulus of flax fibres, with reduced data dispersion compared to traditional macroscopic testing. Furthermore, by reducing the influence of inherent fibre defects and maintaining homogeneity along the length of the fibre, our micro-scale technique provides reliable modulus determination. This work opens avenues for improved understanding and application of natural and man-made fibres, such as glass and optical fibres, in a variety of fields.
Combining the D3 dispersion correction with the neuroevolution machine-learned potential
Authors: Ying Penghua , Fan Zheyong
Published: December 2023

Machine-learned potentials (MLPs) have become a popular approach of modeling interatomic interactions in atomistic simulations, but to keep the computational cost under control, a relatively short cutoff must be imposed, which put serious restrictions on the capability of the MLPs for modeling relatively long-ranged dispersion interactions. In this paper, we propose to combine the neuroevolution potential (NEP) with the popular D3 correction to achieve a unified NEP-D3 model that can simultaneously model relatively short-ranged bonded interactions and relatively long-ranged dispersion interactions. We show that improved descriptions of the binding and sliding energies in bilayer graphene can be obtained by the NEP-D3 approach compared to the pure NEP approach. We implement the D3 part into the gpumd package such that it can be used out of the box for many exchange-correlation functionals. As a realistic application, we show that dispersion interactions result in approximately a 10% reduction in thermal conductivity for three typical metal-organic frameworks.
Parity of polaritons in a molecular aggregate coupled to a single-mode cavity
Authors: Liu Jingyu , Liu Jiani , Yao Yao
Published: December 2023

We investigated the parity of polaritons, particularly the parity of topological polariton states resulting from light fields, in a molecular aggregate with uniform and alternating excitation transfer interaction coupled to a single-mode cavity. We find that all polariton states are with even parity, in terms of parity conservation, and the even-parity edge states of the Su–Schrieffer–Heeger model with alternating excitation transfer interaction induce even-parity topological polariton states. Thus, the odd-parity edge states are almost unaffected. The original odd-parity edge state is then affected with respect to the parity non-conservation case, i.e. the occupation number of the edge states shifts from one edge to another. This result entails the preparation of edge states from the photonic excited states through an adiabatic process.
Development and validation of BVB-UIE: an underwater image-enhancement model with two-layer deep neural network
Authors: Yao Xinyu , He Fengtao , Bai JuRong , Zhang Jianlei
Published: December 2023

Due to the absorption and scattering of light in water, underwater visual visibility is poor, and underwater images usually suffer from color distortion and feature loss, which poses a great challenge for underwater vision tasks. To handle these issues, we present an underwater image enhancement (UIE) method. A Gaussian pyramid is constructed for the degraded underwater images based on an improved visual saliency model, with the characteristics of luminance, orientation, texture, and color. By combining channel and spatial attention mechanisms, a deep asymmetric feature enhancement network is built to preserve the high-dimensional features of the image. In addition, a polynomial loss function is used for the depth hopping supervising constraints during the enhancement process, and the gating signals are employed to control the importance of the features at different spatial locations. These innovations maximize the efficiency of the feature extraction while simplifying the network complexity. Experiments on an open benchmark dataset for UIE show that our method effectively eliminates the color bias and contrast distortion problems while preserving the complex image details compared to the existing UIE algorithms. Objective metrics show a significant improvement in the algorithm, with a 15% increment in the peak signal-to-noise ratio metric compared to the closest competing algorithm.
A vibration correction system for cold atom gravimeter
Authors: Guo Meiying , Bai Jinhai , Hu Dong , Tang Zhimin , You Jianqi , Chen Runnan , Wang Yu
Published: December 2023

Cold atom gravimeters are used to measure the absolute value of the gravitational acceleration. To mitigate the influence of seismic noise on the mirror, a vibration correction system is used. A commercial seismometer CMG-3ESPC is employed to measure the mirror vibration. The transfer function between the mirror vibration and the output of the seismometer is regarded as a proportional element with a time delay. The best proportional element and the best time delay are obtained by minimizing the standard deviation of the fitting residuals of the interference fringe

α
−
P

with vibration correction. This system not only exhibits excellent environmental adaptability but also eliminates the need for rough estimation of local gravitational acceleration during the vibration correction process. The system was built on the homemade cold atom gravimeter to carry out experiments in the laboratory. Compared with the measurement results without vibration correction, the standard deviation of the gravity measurement results was reduced from

120.5
μ

Gal to

4.2
μ

Gal, resulting in a significant reduction by a factor of 28.7. Meanwhile, its sensitivity was significantly improved from 330.8

μ

Gal

Hz

−
1

to 18.0

μ

Gal

Hz

−
1

by performing vibration correction. In the future, this system is expected to carry out comprehensive verification experiments in more complex noisy environments.
Well–posedness of the three–dimensional NLS equation with sphere–concentrated nonlinearity
Authors: Finco Domenico , Tentarelli Lorenzo , Teta Alessandro
Published: December 2023

We discuss strong local and global well–posedness for the three–dimensional NLS equation with nonlinearity concentrated on

S

2

. Precisely, local well–posedness is proved for any C
2 power–nonlinearity, while global well–posedness is obtained either for small data or in the defocusing case under some growth assumptions. With respect to point–concentrated NLS models, widely studied in the literature, here the dimension of the support of the nonlinearity does not allow a direct extension of the known techniques and calls for new ideas.
Canonical curves and Kropina metrics in Lagrangian contact geometry
Authors: Ma Tianyu , Flood Keegan J , Matveev Vladimir S , Žádník Vojtěch
Published: December 2023

We present a Fefferman-type construction from Lagrangian contact to split-signature conformal structures and examine several related topics. In particular, we describe the canonical curves and their correspondence. We show that chains and null-chains of an integrable Lagrangian contact structure are the projections of null-geodesics of the Fefferman space. Employing the Fermat principle, we realize chains as geodesics of Kropina (pseudo-Finsler) metrics. Using recent rigidity results, we show that ‘sufficiently many’ chains determine the Lagrangian contact structure. Separately, we comment on Lagrangian contact structures induced by projective structures and the special case of dimension three.
Symmetric periodic orbits in symmetric billiards
Authors: Ferreira Geraldo César Gonçalves , Oliffson Kamphorst Sylvie , Pinto-de-Carvalho Sônia
Published: December 2023

In this text we study billiards on symmetric ovals and investigate some consequences of the symmetry of the boundary on the dynamics. As it simplifies some calculations, the symmetry helps to obtain the results. We focus on periodic orbits with the same symmetry of the boundary which always exist and prove that typically half of them are elliptic and Moser stable and the other half are hyperbolic with homo(hetero)clinic intersections.
Spectrality of random convolutions generated by finitely many Hadamard triples
Authors: Li Wenxia , Miao Jun Jie , Wang Zhiqiang
Published: December 2023

Let

{
(

N
j

,

B
j

,

L
j

)
:
1
⩽
j
⩽
m
}

be finitely many Hadamard triples in

R

. Given a sequence of positive integers

{

n
k

}

k
=
1

∞

and

ω
=
(

ω
k

)

k
=
1

∞

∈
{
1
,
2
,
…
,
m

}

N

, let

μ

ω
,
{

n
k

}

be the infinite convolution given by

μ

ω
,

n
k

=

δ

N

ω
1

−

n
1

B

ω
1

∗

δ

N

ω
1

−

n
1

N

ω
2

−

n
2

B

ω
2

∗
⋯
∗

δ

N

ω
1

−

n
1

N

ω
2

−

n
2

⋯

N

ω
k

−

n
k

B

ω
k

∗
⋯
.

In order to study the spectrality of

μ

ω
,
{

n
k

}

, we first show the spectrality of general infinite convolutions generated by Hadamard triples under the equi-positivity condition. Then by using the integral periodic zero set of Fourier transform we show that if

g
c
d

(

B
j

−

B
j

)
=
1

for

1
⩽
j
⩽
m

, then all infinite convolutions

μ

ω
,
{

n
k

}

are spectral measures. This implies that we may find a subset

Λ

ω
,
{

n
k

}

⊆

R

such that

{

e
λ

(
x
)
=

e

2
π
i
λ
x

:
λ
∈

Λ

ω
,
{

n
k

}

}

forms an orthonormal basis for

L
2

(

μ

ω
,
{

n
k

}

)

.
An in-reachability based classification of invariant synchrony patterns in weighted coupled cell networks
Authors: Sequeira P M , Hespanha J P , Aguiar A P
Published: December 2023

This paper presents an in-reachability based classification of invariant synchrony patterns in coupled cell networks (CCNs). These patterns are encoded through partitions on the set of cells, whose subsets of synchronised cells are called colours. We study the influence of the structure of the network in the qualitative behaviour of invariant synchrony sets, in particular, with respect to the different types of (cumulative) in-neighbourhoods and the in-reachability sets. This motivates the proposed approach to classify the partitions into the categories of strong, rooted and weak, according to how their colours are related with respect to the connectivity structure of the network. Furthermore, we show how this classification system acts under the partition join (

∨

) operation, which gives us the synchrony pattern that corresponds to the intersection of synchrony sets.
Discriminative fusion of moments-aligned latent representation of multimodality medical data
Authors: Xie Jincheng , Zhong Weixiong , Yang Ruimeng , Wang Linjing , Zhen Xin
Published: December 2023

Fusion of multimodal medical data provides multifaceted, disease-relevant information for diagnosis or prognosis prediction modeling. Traditional fusion strategies such as feature concatenation often fail to learn hidden complementary and discriminative manifestations from high-dimensional multimodal data. To this end, we proposed a methodology for the integration of multimodality medical data by matching their moments in a latent space, where the hidden, shared information of multimodal data is gradually learned by optimization with multiple feature collinearity and correlation constrains. We first obtained the multimodal hidden representations by learning mappings between the original domain and shared latent space. Within this shared space, we utilized several relational regularizations, including data attribute preservation, feature collinearity and feature-task correlation, to encourage learning of the underlying associations inherent in multimodal data. The fused multimodal latent features were finally fed to a logistic regression classifier for diagnostic prediction. Extensive evaluations on three independent clinical datasets have demonstrated the effectiveness of the proposed method in fusing multimodal data for medical prediction modeling.
Evaluation of monte carlo to support commissioning of the treatment planning system of new pencil beam scanning proton therapy facilities
Authors: Botnariuc D , Court S , Lourenço A , Gosling A , Royle G , Hussein M , Rompokos V , Veiga C
Published: December 2023

Objective. To demonstrate the potential of Monte Carlo (MC) to support the resource-intensive measurements that comprise the commissioning of the treatment planning system (TPS) of new proton therapy facilities. Approach. Beam models of a pencil beam scanning system (Varian ProBeam) were developed in GATE (v8.2), Eclipse proton convolution superposition algorithm (v16.1, Varian Medical Systems) and RayStation MC (v12.0.100.0, RaySearch Laboratories), using the beam commissioning data. All models were first benchmarked against the same commissioning data and validated on seven spread-out Bragg peak (SOBP) plans. Then, we explored the use of MC to optimise dose calculation parameters, fully understand the performance and limitations of TPS in homogeneous fields and support the development of patient-specific quality assurance (PSQA) processes. We compared the dose calculations of the TPSs against measurements (DDTPSvs.Meas.) or GATE (DDTPSvs.GATE) for an extensive set of plans of varying complexity. This included homogeneous plans with varying field-size, range, width, and range-shifters (RSs) (n = 46) and PSQA plans for different anatomical sites (n = 11). Main results. The three beam models showed good agreement against the commissioning data, and dose differences of 3.5% and 5% were found for SOBP plans without and with RSs, respectively. DDTPSvs.Meas. and DDTPSvs.GATE were correlated in most scenarios. In homogeneous fields the Pearson’s correlation coefficient was 0.92 and 0.68 for Eclipse and RayStation, respectively. The standard deviation of the differences between GATE and measurements (±0.5% for homogeneous and ±0.8% for PSQA plans) was applied as tolerance when comparing TPSs with GATE. 72% and 60% of the plans were within the GATE predicted dose difference for both TPSs, for homogeneous and PSQA cases, respectively. Significance. Developing and validating a MC beam model early on into the commissioning of new proton therapy facilities can support the validation of the TPS and facilitate comprehensive investigation of its capabilities and limitations.
Structural approach to charge density waves in low-dimensional systems: electronic instability and chemical bonding
Authors: Pouget Jean-Paul , Canadell Enric
Published: December 2023

The charge density wave (CDW) instability, usually occurring in low-dimensional metals, has been a topic of interest for longtime. However, some very fundamental aspects of the mechanism remain unclear. Recently, a plethora of new CDW materials, a substantial fraction of which is two-dimensional or even three-dimensional, has been prepared and characterised as bulk and/or single-layers. As a result, the need for revisiting the primary mechanism of the instability, based on the electron–hole instability established more than 50 years ago for quasi-one-dimensional (quasi-1D) conductors, has clearly emerged. In this work, we consider a large number of CDW materials to revisit the main concepts used in understanding the CDW instability, and emphasise the key role of the momentum dependent electron–phonon coupling in linking electronic and structural degrees of freedom. We argue that for quasi-1D systems, earlier weak coupling theories work appropriately and the energy gain due to the CDW and the concomitant periodic lattice distortion (PLD) remains primarily due to a Fermi surface nesting mechanism. However, for materials with higher dimensionality, intermediate and strong coupling regimes are generally at work and the modification of the chemical bonding network by the PLD is at the heart of the instability. We emphasise the need for a microscopic approach blending condensed matter physics concepts and state-of-the-art first-principles calculations with quite fundamental chemical bonding ideas in understanding the CDW phenomenon in these materials.
Existence of complex magnetic ground state and topological Hall effect in centrosymmetric silicide DyScSi
Authors: Yadav Kavita , P Koushik , Singh Saurabh , Hagihala Masato , Mukherjee K
Published: December 2023

Topological Hall effect (THE) originating from non-trivial spin arrangements in magnetic materials has been extensively investigated in recent years. In this context, a centrosymmetric ternary silicide, DyScSi, is explored. Here we show that, a complex magnetic ground state drives THE in a centrosymmetric system. Temperature dependent magnetisation and neutron diffraction results establish the presence of commensurate antiferromagnetic (AFM) phase around 92 K, followed by an incommensurate AFM phase below 40 K. Additionally, two cluster glass transitions near 20 and 8 K, are also noted. These observed features arise due competing AFM and FM interactions. In conjunction with this, a finite contribution of THE is also observed in the intermediate field regime (8–30 kOe), at low temperature in DyScSi. The behaviour of this silicide appears to be fascinating in terms of interplay between complex magnetic ground state and THE in centrosymmetric structure.
Excitation of wakefields in carbon nanotubes: a hydrodynamic model approach
Authors: Martín-Luna P , Bonatto A , Bontoiu C , Xia G , Resta-López J
Published: December 2023

The interactions of charged particles with carbon nanotubes (CNTs) may excite electromagnetic modes in the electron gas produced in the cylindrical graphene shell constituting the nanotube wall. This wake effect has recently been proposed as a potential novel method of short-wavelength high-gradient particle acceleration. In this work, the excitation of these wakefields is studied by means of the linearized hydrodynamic model. In this model, the electronic excitations on the nanotube surface are described treating the electron gas as a 2D plasma with additional contributions to the fluid momentum equation from specific solid-state properties of the gas. General expressions are derived for the excited longitudinal and transverse wakefields. Numerical results are obtained for a charged particle moving within a CNT, paraxially to its axis, showing how the wakefield is affected by parameters such as the particle velocity and its radial position, the nanotube radius, and a friction factor, which can be used as a phenomenological parameter to describe effects from the ionic lattice. Assuming a particle driver propagating on axis at a given velocity, optimal parameters were obtained to maximize the longitudinal wakefield amplitude.
Design of S-box multi-objective optimization algorithm based on combined chaotic system
Authors: Tong Xiaojun , Cheng Liming , Wang Zhu , Zhang Miao
Published: December 2023

S-box is the only nonlinear cryptographic component that determines the security of the block cipher. The higher the security of the S-box, the higher the security of the block cipher. Therefore, this paper proposes an S-box multi-objective optimization algorithm based on the combined chaotic system. Firstly, designing an integrated chaotic system based on a fractional index and its dynamic behavior is studied; it shows incredibly high-performance stability and chaotic parameter range coverage in the entire parameter space. A novel chaotic S-box construction algorithm is proposed based on the combined chaotic system. It introduces a linear congruential pseudo-random number generator to extend the sequence period and scramble the chaotic S-box through Henon mapping to improve the nonlinearity of the s-box. Finally, introducing a teaching and learning multi-objective optimization model and the performance evaluation criteria of the S-box are incorporated into the design of the objective function; this design enables the resulting S-box to perform well under multiple performance indicators, and then the approximate optimal S-box in the population is obtained. Through the performance test of the approximate optimal S-box, the comparative analysis shows that the S-box has good cryptographic performance, can resist linear analysis and differential analysis, and has a good application prospect in lightweight cipher.
Temperature and volume dependence of pion-pion scattering lengths*
Authors: Wang 王 Qing-Wu 庆武 , Guo 郭 Hua-Zhong 华忠
Published: December 2023

The s-wave pion-pion scattering lengths

and

are studied at finite temperature and in finite spatial volume under the framework of the Nambu–Jona-Lasinio model. The behavior beyond the pseudo transition temperature is investigated using proper time regularization. The scattering length

exhibits singularity near the Mott temperature, and

is a continuous but non-monotonic function of temperature. We present the effect of finite volume on the scattering length and find that

can be negative and its singularity disappears at small volumes, which may hint at the existence of a chiral phase transition with decreasing volume.
Variable Stars in the 50BiN Open Cluster Survey. III. NGC 884
Authors: Wang Lin-Hong , Nie Qian-Heng , Wang Kun , Chen Xiao-Dian , Zhang Chun-Guang , Deng Li-Cai , Zhang Xiao-Bin , Chen Tian-Lu
Published: December 2023

Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way. Variable stars in open clusters provide a unique way to accurately probe the internal structure, temporal and dynamical evolutionary stages of individual stars and the host cluster. The most powerful tool for such studies is time-domain photometric observations. This paper follows the route of our previous work, concentrating on a photometric search for variable stars in NGC 884. The target cluster is the companion of NGC 869, forming the well-known double cluster system that is gravitationally bound. From the observation run in 2016 November, a total of 9247 B-band CCD images and 8218 V-band CCD images were obtained. We detected a total of 15 stars with variability in visual brightness, including five Be stars, three eclipsing binaries, and seven of unknown types. Two new variable stars were discovered in this work. We also compared the variable star content of NGC 884 with its companion NGC 869.
Impedance of in-air undulator vacuum chamber in HEPS
Authors: Li Jintao , Wang Na , Yue Sen , Tian Saike
Published: December 2023

Undulators with small gap have been widely used in various
light sources all over the world for the demand of high brilliance.
A large number of in-air undulators with small gap will be installed
in the storage ring of the High Energy Photon Source, and become one
of the important impedance contributors. Antechambers are adopted
for the bypass of the synchrotron radiations, as well as to reach
high vacuum in the beam pipe with small aperture. Due to the
asymmetric structure of the vacuum chamber, monopole wakefield in
the transverse planes will be excited by the beam passage. In
addition, photon absorbers will be installed in the vacuum chamber
of the in-air undulators to shield the downstream components, which
will introduce extra resonances in the transverse planes. In this
paper, a series of numerical simulations are performed to
investigate the impedance of the in-air undulator vacuum chamber.
The high order modes generated by the photon absorber and their
mitigations are also investigated.
Development of a high-voltage radio frequency power supply for quadrupole mass spectrometers with a wide dynamic measurement range
Authors: Wang Xinghui , Cheng Yongjun , Chen Lian , Dong Meng , Feng Tianyou , Zhao Lan , Zhang Ruifang
Published: December 2023

The core component of a quadrupole mass spectrometer is the
quadrupole mass filter, serving a crucial role in ion analysis. It
operates by applying two sets of high-voltage, high-frequency
signals with equal amplitude and opposing phases through the radio
frequency power supply, capitalizing on variations in the electric
field and differences in mass-to-charge ratios to separate incoming
ions. This study leverages direct digital frequency synthesis
technology and multi-stage voltage amplification techniques to
design a tailored radio frequency power supply for quadrupole mass
spectrometers with a broad mass range. Practical testing
demonstrates that this power supply generates radio frequency
high-voltage signals with a peak-to-peak voltage ranging from
2.210 V to 4.220 kV at a resonant frequency of 1.240 MHz,
facilitating the separation of ions with distinct m/z values. Furthermore, the radio frequency power supply is integrated
into a Self-developed quadrupole mass spectrometer, enabling an
assessment of the mass range, resolution, stability of the
spectrometer. The results of these assessments confirm that the
developed power supply accommodates scanning of m/z value ions in
the range of 1 to 1067 while maintaining an absolute resolution of
less than m/z = 1 units and an instrument stability of 2.00% over
four hours.and keywords.
Characteristics of population exposure to climate extremes from regional to global 1.5 °C and 2.0 °C warming in CMIP6 models
Authors: Qin Peihua , Xie Zhenghui , Jia Binghao , Sun Shuai
Published: December 2023

The intensities and occurrences of heat extremes are projected to increase in a warmer climate, and relevant policies have been established to address different warming levels. However, how climate extremes change at regional warming levels is not well-known because changes in temperature vary over different regions. This study investigated climate extremes and population exposure to these extremes at regional and global 1.5 °C or 2.0 °C warming over 58 reference regions with 16 Coupled Model Intercomparison Project, 6th phase models. The years of reaching local 1.5 °C or 2.0 °C warming occurred earlier than the timing of global warming over certain land areas, with more than 30 years advance in northern high latitude land areas. Heat extremes are projected to increase in all reference regions under regional and global 1.5 °C or 2.0 °C warming. Moving from regional to global 1.5 °C or 2.0 °C warming, heat extremes were found to increase over most land areas, especially over mid- and high-latitude areas. Population exposure to climate extremes increased over more than half the land regions under regional to global 1.5 °C or 2.0 °C warming. Changes in population exposure to absolute heat extremes were mainly generated by changes in population over about 34 land regions, whereas changes in population exposure to percentile-based heat extremes over more than 40 land regions were mostly due to changes in climate extremes. These results provided references to establish relevant strategies at regional scale to address possible risks related to climate extremes.
Development and validation of synchronous spectrofluorimetric method for the simultaneous determination of duvelisib and moxifloxacin: greenness metric assessment and application to a pharmacokinetic study in rats
Authors: Othman Weam M , Al-Zoman Nourah Z , Darwish Ibrahim A , Almomen Aliyah , Farid Nehal F , Abdallah Fatma F , Saad Samah S
Published: December 2023

Duvelisib (DUV) is a potent anticancer drug whereas Moxifloxacin (MOX) is an antimicrobial drug with anti-proliferative potency against cancerous cells, which is empirically administered in cancer treatment. DUV and MOX combination is commonly prescribed to combat infections in patients while they are under chemotherapy treatment. This study describes, for the first time, the development of a simple and green synchronous spectrofluorimetric (SSF) method for the simultaneous estimation of DUV and MOX in plasma. DUV and MOX were quantified at 273 and 362 nm, respectively without interference between each other at Δλ of 120 nm. The experimental variables influencing fluorescence intensities were thoroughly investigated and the optimum conditions were established. At pH 3.5, the optimum synchronous fluorescence intensity (SFI) was achieved in water solvent by using sodium acetate buffer solution. Calibration curves for DUV and MOX, correlating the SFI with the corresponding drug concentration, were linear in the range of 50–1000 ng mL−1 for both drugs, with good correlation coefficients. The method was extremely sensitive, with limits of detection of 24 and 22 ng mL−1, and limits of quantitation of 40 and 45 ngmL−1 for DUV and MOX, respectively. The SSF method was validated according to the Food and Drug Administration (FDA) guidelines for validation of analytical procedures, and the validation parameters were acceptable. The proposed SSF method was applied to the pharmacokinetic and bioavailability studies in rats’ plasma after single concurrent oral administration of both drugs. The results of the study revealed that caution should be taken with DUV dose when concurrently administered with MOX. The greenness of SSF method was assessed by three different metric tools namely Analytical Eco-scale, Green Analytical Procedure Index, and Analytical Greenness Calculator. The results confirmed that SSF method is an eco-friendly and green analytical approach. In conclusion, the proposed SSF method is a valuable tool for pharmacokinetic/bioavailability studies and therapeutic drug monitoring of simultaneously administered DUV and MOX.
Solution-processed graphene films for electrochemical monitoring of extracellular nitric oxide released by breast cancer cells
Authors: Butler Derrick , Sankhe Chinmay S , Khamsi Pouya Soltan , Gomez Esther W , Ebrahimi Aida
Published: December 2023

Nitric oxide (NO) plays an important role in cardiovascular function, immune response, and intercellular signaling. However, due to its short lifetime, real-time detection of NO is challenging. Herein, an electrochemical sensor based on fibronectin-modified, solution-processed graphene ink for NO detection is developed using a facile fabrication method involving spin-coating and hot-plate annealing. The sensor is first electrochemically characterized with a NO donor, spermine NONOate, exhibiting a dynamic range of 10–1000 μM. The fibronectin-functionalized graphene supports the attachment and growth of MDA-MB-231 breast cancer cells, as confirmed by optical microscopy. Extracellular NO production is stimulated using the amino acid L-arginine. NO production results in morphological changes to the adhered cells, which are reversible upon the addition of the NO synthase antagonist Nω-nitro-L-arginine methyl ester. The production of NO is also confirmed using real-time amperometric measurements with the fibronectin-functionalized graphene sensors. While this work focuses on NO detection, this potentially scalable platform could be extended to other cell types with envisioned applications including the high-throughput evaluation of therapeutics and biocompatible coatings.