bluuebunny/crossref_metadata_2025 huggingface dataset:
Low turn-on voltage AlGaN/GaN Schottky barrier diode with a low work function anode and high work function field plate
Authors: Shi Yuhao , Li Guoxin , He Yuhao , Guo Zhonghong , Shang Jianbo , Li Xiaohang , Gao Fangliang , Li Shuti
Published: September 2024

AlGaN/GaN Schottky barrier diodes (SBDs) with a low work function W anode and a high work function Ni field plate on sapphire substrates are investigated in this Letter. The low work function metal W leads to the low turn-on voltage, while the high work function metal Ni maintains the leakage current and increases the breakdown voltage. An ultralow turn-on voltage of 0.23 V determined by the positive fixed charge at the AlGaN/Si3N4 interface is achieved in this W/Ni SBD. More importantly, benefitting from the dual-metal anode/field plate structure, the on-resistance decreases from 7.99 to 5.53 Ω mm, and the breakdown voltage increases from 493 to 1219 V. In addition, the turn-on voltage decreases less than 57%, and the on-resistance increases less than 186% at a high temperature up to 120 °C. The W/Ni SBD with a cathode–anode length of 18 μm and a field plate length of 4 μm shows a low turn-on voltage of 0.23 V, a low on-resistance of 5.53 Ω mm, a leakage current of 0.65 mA/mm, and a high breakdown voltage of 1.21 kV, indicating a great potential for power electronic applications.
Mixing and ignition characteristics of laser-induced solid fuel pyrolysis under wide-range variation of crossflow
Authors: Xia Hanqing , Wang Ningfei , Pang Jiantao , Yan Chunhui , Wu Yi
Published: September 2024

A theoretical model has been developed to elucidate the thermal initiation laser ignition process of solid fuel. This model comprehensively explores both the heating process of solid fuel and the mixing process of gas-phase pyrolysis gases with crossflow conditions. A two-dimensional transient numerical model has been established and validated through experimental investigations across a spectrum of crossflow fluxes (ranging from 20 to 150 kg/m2/s) and pressures (ranging from 0.15 to 1.83 MPa). The study involves a quantitative analysis of the influence of key macroscopic parameters, including laser energy levels, combustion pressure, and flow rates, on essential mixing characteristics. The solid fuel heating process is segmented into two distinct phases: a preheating phase and a pyrolysis phase, with the latter exhibiting considerably higher heating rates. Notably, a direct linear relationship is observed between the laser energy levels and the rate of heating. It reveals that the dynamics of pyrolysis product mixing are primarily determined by the solid fuel pyrolysis rate and the prevailing crossflow conditions. The dimensionless penetration depth, which measures the extent of pyrolysis product mixing with crossflow, demonstrates an exponential positive correlation with pyrolysis rates and oxidizer flow rates while displaying a negative correlation with combustion pressure. This analysis includes the quantitative determination of proportionality constants and power exponents within the correlations. Finally, the study delves into the intricate interplay between crossflow conditions and the criteria for laser ignition, specifically ignition temperature and the flammable lower limit.
Computing linear optical spectra in the presence of nonadiabatic effects on graphics processing units using molecular dynamics and tensor-network approaches
Authors: Lambertson Evan , Bashirova Dayana , Hunter Kye E. , Hansen Benhardt , Zuehlsdorff Tim J.
Published: September 2024

We compare two recently developed strategies, implemented in open source software packages, for computing linear optical spectra in condensed phase environments in the presence of nonadiabatic effects. Both approaches rely on computing excitation energy and transition dipole fluctuations along molecular dynamics (MD) trajectories, treating molecular and environmental degrees of freedom on the same footing. Spectra are then generated in two ways: in the recently developed Gaussian non-Condon theory, the linear response functions are computed in terms of independent adiabatic excited states, with non-Condon effects described through spectral densities of transition dipole fluctuations. For strongly coupled excited states, we instead parameterize a linear vibronic coupling Hamiltonian directly from spectral densities of energy fluctuations and diabatic couplings computed along the MD trajectory. The optical spectrum is then calculated using powerful, numerically exact tensor-network approaches. Both the electronic structure calculations to sample system fluctuations and the quantum dynamics simulations using tensor-network methods are carried out on graphics processing units, enabling rapid calculations on complex condensed phase systems. We assess the performance of the approaches using model systems in the presence of a conical intersection and the pyrazine molecule in different solvent environments.
Observation of the enhanced dual-split photonic spin Hall effect in wavelength domain via a helical fiber grating
Authors: Meng Zhang , Zhao Hua , Seo Yuhei , Oiwa Shiryu , Wang Peng , Li Hongpu
Published: September 2024

To date, the photonic spin Hall effect (PSHE) has been studied and observed only in the space and momentum domains. Direct observation of the PSHE in the wavelength domain remains unexplored. In this work, we demonstrate both theoretically and experimentally the enhanced PSHE in the wavelength domain via a helical long-period fiber grating (HLPG), where the spin-dependent dual-split in the transmission spectrum of the utilized HLPG has been observed. This is unlike the PSHEs reported thus far, where a mono-splitting of the light is observed in either the space or the momentum domains. The proposed method provides an additional degree of freedom to observe the PSHE, which paves the way for exploiting all fiber-based HLPGs in chiral photonics, chiral sensors, and fine precise measurements.
Barrier-crossing transition-path times for non-Markovian systems
Authors: Lavacchi L. , Netz R. R.
Published: September 2024

By simulation and asymptotic theory, we investigate the transition-path time of a one-dimensional finite-mass reaction coordinate crossing a double-well potential in the presence of non-Markovian friction. First, we consider single-exponential memory kernels and demonstrate that memory accelerates transition paths compared to the Markovian case, especially in the low-mass/high-friction limit. Then, we generalize to multi-exponential kernels and construct an asymptotic formula for the transition-path time that compares well with simulation data.
Blue shift of the absorption onset and bandgap bowing in rutile GexSn1−xO2
Authors: Kluth Elias , Nagashima Yo , Osawa Shohei , Hirose Yasushi , Bläsing Jürgen , Strittmatter André , Goldhahn Rüdiger , Feneberg Martin
Published: September 2024

The ordinary dielectric functions (DFs) of rutile GexSn1−xO2 thin films grown by pulsed laser deposition have been obtained by spectroscopic ellipsometry from the near infrared to the ultraviolet range. Additionally, the Ge content x and the lattice parameters were determined by energy dispersive x-ray spectroscopy and x-ray diffraction, respectively. The lattice parameter deviates partly from Vegard's law due to epitaxial strain. In the DFs, a blue shift of the onset of absorption with increasing Ge content is observed. Evaluation of the DFs yields the characteristic transition energies at the absorption onset, and the corresponding bowing parameter of the dipole allowed direct bandgap of b=(0.70± 0.09) eV.
Experimental and numerical study on dynamics of viscoelastic liquid cone in flow focusing
Authors: Wang Ming , Mu Kai , Zhao Chengxi , Wu Yanfeng , Xu Wenshuai , He Xiuli , Si Ting
Published: September 2024

The effects of viscoelasticity on the stability and morphology of the liquid cone in liquid–liquid flow focusing are investigated experimentally and numerically. The particle tracers are utilized in experiments to visualize the flow fields, and the Oldroyd-B model is applied in numerical simulations to describe the viscoelastic characteristics of the liquid cone. Based on the quantitative analyses on the elastic stresses and forces inside the cone, the influence of viscoelasticity on the startup process of the liquid cone is first investigated. The stretching and shrinking stages of the viscoelastic cone are identified, and the startup process of the Newtonian cone is also studied for comparison. By considering the force balance at local jet position, a scaling analysis is proposed to give the criterion for the establishment of the stable cone, which indicates that the axial elastic stress can promote the cone stability. Upon a stable liquid cone, the influences of viscoelasticity on the interface profile and flow field of the cone are further analyzed, indicating that an increase in viscoelasticity leads to more shrinkage of the cone interface. The shrinkage of cone leads to the acceleration of focused liquid and thus the decrease in the recirculation flow size. This fundamental work provides scientific guidance for understanding the influences of viscoelasticity in flow focusing process, contributing to the industrial applications of microdroplets production.
Theory of high-temperature superfluorescence in hybrid perovskite thin films
Authors: Fainberg B. D. , Osipov V. Al.
Published: September 2024

The recent discovery of high-temperature superfluorescence in hybrid perovskite thin films has opened new possibilities for harnessing macroscopic quantum phenomena in nanotechnology. This study aimed to elucidate the mechanism that enables high-temperature superfluorescence in these systems. The proposed model describes a quasi-2D Wannier exciton in a thin film that interacts with phonons via the longitudinal optical phonon–exciton Fröhlich interaction. We show that the super-radiant properties of the coherent state in hybrid perovskites are stable against perturbations caused by the longitudinal optical phonon–exciton Fröhlich interaction. Using the multiconfiguration Hartree approach, we derive semiclassical equations of motion for a single-exciton wavefunction, where the vibrational degrees of freedom interact with the Wannier exciton through a mean-field Hartree term. Super-radiance is effectively described by a non-Hermitian term in the Hamiltonian. The analysis was then extended to multiple excited states using the semiclassical Hamiltonian as the basic model. We demonstrate that the ground state of the model exciton Hamiltonian with long-range interactions is a symmetric Dicke super-radiant state, where the Fröhlich interaction is nullified. The additional density matrix-based consideration draws an analogy between this system and stable systems, where the conservation laws determine the nullification of the constant (momentum-independent) decay rate part. In the exciton–phonon system, nullification is associated with the absence of a momentum-independent component in the Wannier exciton–phonon interaction coupling function.
The best whistler: A cavitating tip vortex
Authors: Qian Zhaohui , Ye Weixiang , Zeng Yongshun , Peng Xiaoxing , Luo Xianwu
Published: September 2024

The discrete tone radiated from a cavitating tip vortex, known as “vortex singing,” was first recognized in 1989, but its sound generation mechanism has remained a mystery for over 30 years. In this Letter, by means of the correction for the cavitation bubble dynamics and the dispersion relation of cavity interfacial waves, we found that after the far-end disturbances propagate upstream, the whistling vortex should be triggered by near-end sound sources, the breathing mode waves. Further utilizing the theoretical solutions for singing lines and the potential singing cavitation number with frequency, we accurately identified all available tests for seeking the vortex singing over the past three decades, which not only demonstrates that the vortex singing frequency is only determined by the measurable mean cavity radius (rc), cavitation number (σ), and desinent cavitation number (σd) in experiments, but also responses to a long-standing perplexity: why such a best whistler is able to appear only within a narrow range of the cavitation number.
Layered heterogeneous structures integrated device for multiplication, division arithmetic unit and multiple-physical sensing
Authors: Xu Jie , Zhang Ming-Zhe , Tang Zhao , Zhang Hai-Feng
Published: September 2024

A layered heterogeneous structure (LHS), consisting of silver, liquid crystal, and nonlinear dielectric layers, is proposed to realize functions of computing and sensing. By leveraging the optical Tamm state, the intrinsic absorption principle of liquid crystal, and nonlinear effects, the design of an integrated device capable of passive multiplication and division operations, along with high-performance multi-physical quantity sensing functionalities, is achieved. The given LHS exhibits Janus properties, with different physical functions manifested depending on the direction of electromagnetic wave (EW) propagation. During forward propagation of EWs, the LHS displays high and sharp absorptivity peaks at 774.8 and 1517.6 nm. The relationship between the two peaks approximates a frequency multiplication factor of 1.960, enabling signal multiplication. Furthermore, the two absorptivity peaks at different wavelengths facilitate the sensing of serum creatinine solution concentration and external pressure, with sensitivity (S), quality factors (Q), and figure of merit (FOM) of 266.76 μmol L−1/nm and 213.33 GPa/nm, as well as 248.76 and 348.22, 84.1 L (μmol)−1 and 49.06 GPa−1, respectively. During backward propagation of EWs, absorptivity peaks with distinct resolutions are observed at 1423 and 2809 nm, with a multiple relationship between them of 1.974, enabling frequency doubling for signal division. Additionally, the absorptivity curve facilitates temperature sensing over a wide range from 257 to 347 K. Owing to the unique temperature S of liquid crystal, different sensitivities and resolutions are observed at 257 to 297 K and 307 to 347 K, with S of 1.015 and 0.686 K/nm, and corresponding Q and FOM of 21.57 and 12.576, 0.076 K−1 and 0.003 04 K−1, respectively.
Chebyshev spectral Newton iterative analysis on unsteady oblique stagnation flow of Maxwell fluids over an oscillating-rotating disk with Cattaneo–Christov double diffusion
Authors: Xiang Junlin , Bai Yu , Zhang Yan , Liu Chunyan
Published: September 2024

Oblique stagnation flow on a rotating disk is commonly observed in processes such as spinning coating and thin film deposition techniques. The investigation of the unsteady oblique stagnation point flow for Maxwell fluid over an oscillating-rotating disk embedded in a porous medium is meticulously conducted by employing the Darcy–Maxwell framework in conjunction with Cattaneo–Christov double diffusion model. A transformation of similarity is applied to reframe the governing equations into a system of non-dimensional coupled partial differential equations, whose numerical solutions are secured by the Chebyshev Spectral Newton Iterative Scheme. The outcomes underscore that an escalation in the Darcy parameter escalates the resistance within the porous medium, consequently leading to a reduction in velocity. Both the first-order slip and the second-order slip mitigate the fluid's interaction with the disk wall, leading to a retardation in flow velocity. Additionally, the presence of augmented thermal radiation parameters is observed to enhance heat transfer efficiency, resulting in a more homogenized temperature distribution. The two-dimensional and three-dimensional streamlines provide a precise depiction of the flow characteristics at the oblique stagnation point on the oscillating-rotating disk. These findings offer a theoretical foundation that can be instrumental for forthcoming research in analogous fields.
Three-dimensional object reconstruction based on spin–orbit interaction of light
Authors: Wang Yunxia , Yang Hua , Liu Jiawei , Xu Dingyu , Yang Qiang , Shou Yichang , Luo Hailu
Published: September 2024

Three-dimensional (3D) reconstruction has received extensive attention in recent years and is of great significance to various application fields. We propose a simple method of 3D object reconstruction based on spin–orbit interactions occurring from light reflection at the air–glass interface. By rotating the object, edge images of the object in various orientations are obtained; we overlap these edge images to ultimately reconstruct the 3D object. This 3D image detection based on spin–orbit interaction of light provides a low energy consumption, low cost, and more algorithmic method compared to traditional 3D image processing. This can be used in fields such as medicine, autonomous vehicles, planetary observation, and other areas.
Optical measurement and feedback control of a ferromagnetic mechanical resonator
Authors: Qiao Hong-Yi , Xu Guan-Ting , Shen Zhen , Wang Yu , Guo Guang-Can , Hu Shui-Ming , Dong Chun-Hua
Published: September 2024

The measurement and control of mechanical resonators are critical for cavity magnomechanics, which has emerged as an important frontier for hybrid quantum systems based on magnonics. Traditional microwave-based measurements require handling high-frequency signals and cannot achieve field distribution detection. Here, we demonstrate a method for optically measuring and manipulating a ferromagnetic mechanical resonator. This technique allows for direct observation of the response and field distribution of mechanical oscillations during magnomechanically induced transparency/absorption processes, confirming that the mechanical mode S1,2 is coupled with the magnon. The optical measurement not only serves to validate the magnomechanical coupling theory but also reduces the necessity for high-frequency measurements. Furthermore, we utilize the instantaneously measured results to implement feedback control of the self-oscillating mechanical resonator to overcome the dynamical back-action limit, achieving a threefold enhancement of phonon lasing amplitude. This feedback control lays the foundation for the study of quantum cavity magnomechanics, such as the feedback cooling of a magnomechanical resonator.
The treatment gap for deep brain stimulation in Parkinson’s disease: a comparative analysis of cost and utilisation in high-income countries
Authors: Stein Athena , Higgins Nathan , Gajwani Mehul , Gericke Christian A.
Published: September 2024

Objective Parkinson’s disease (PD) is one of the most prevalent neurodegenerative disorders, globally affecting approximately 120 per 100,000 people by age 70. Deep brain stimulation (DBS) is a US Federal Drug Administration (FDA)-approved and highly effective treatment for late-stage PD. However, country-specific reimbursement regulations and health policies may affect access to PD-DBS. We aimed to evaluate the uptake rate and ‘treatment gap’ for DBS across high-income countries. Methods We reviewed previous literature to investigate the cost and utilisation of PD-DBS in high-income countries across Asia, Europe, Oceania, and North America (Australia, Canada, France, Germany, Hong Kong, Japan, Korea, the Netherlands, New Zealand, Norway, Spain, Switzerland, UK, and USA). Using previous estimates of DBS candidate eligibility rates, we calculated theoretical DBS uptake rates and treatment gaps nationally. Results PD-DBS utilisation was highest in Australia and the USA and lowest in Korea and New Zealand. The total cost of PD-DBS in the first 12 months was highest in the USA and France and lowest in the UK and Germany. The utilisation rate (i.e. uptake rate) of PD-DBS (% DBS surgeries per PD case) was highest in Australia and the USA, and lowest in New Zealand and the UK, where the treatment gap reflected these trends. Conclusions Our results highlight differences in access to DBS for PD patients among high-income countries, which we discuss in the context of health systems. Better access to effective PD treatments such as DBS is critical given the increasing prevalence of PD in an ageing world and the associated, avoidable morbidity.
Are tuna always hungry? A deep dive into stomach-fullness measures in the western and central Pacific Ocean
Authors: Machful Pauline , Portal Annie , Macdonald Jed , Allain Valerie , Scutt Phillips Joe , Potts Joanne , Nicol Simon
Published: September 2024

Context Understanding tuna diet and its drivers can provide valuable insights into the dynamics of pelagic ecosystems and their capacity to adapt to environmental and human-induced stressors. Aims To reconstruct tropical tuna dietary histories by using different metrics of stomach fullness and to assess their association with fisheries-related, environmental and biological covariates. Methods We examined stomachs from 8229 skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares) and bigeye tuna (T. obesus) captured in the western and central Pacific Ocean between 2001 and 2021, classified each on the basis of categorical and continuous fullness metrics, then built statistical models to gauge covariate effects. Key results Only models for the binary fullness metric (i.e. empty or non-empty) performed well. Tuna with empty stomachs were more likely to be caught on active gear (e.g. purse seine) and earlier in the day. Skipjack and bigeye tuna with empty stomachs were more likely to be associated with floating objects (e.g. fish-aggregating devices). Conclusions Our results add to the evidence that tropical tunas forage more effectively during the day and more actively when not associated with floating objects. At the individual level, tuna stomach fullness is highly variable. Implications Further research is needed to understand the factors governing this promising indicator of ecosystem change.
Generating interstitial water within the persisting tetrahedral H-bond network explains density increase upon compressing liquid water
Authors: Förster Mirko , Ukoji Nnanna , Sahle Christoph J. , Niskanen Johannes , Sakrowski Robin , Surmeier Göran , Weis Christopher , Irifune Tetsuo , Imoto Sho , Yavas Hasan , Huotari Simo , Marx Dominik , Sternemann Christian , Tse John S.
Published: September 2024

Despite its ubiquitous nature, the atomic structure of water in its liquid state is still controversially debated. We use a combination of X-ray Raman scattering spectroscopy in conjunction with ab initio and path integral molecular dynamics simulations to study the local atomic and electronic structure of water under high pressure conditions. Systematically increasing fingerprints of non-hydrogen-bonded H

2

O molecules in the first hydration shell are identified in the experimental and computational oxygen K-edge excitation spectra. This provides evidence for a compaction mechanism in terms of a continuous collapse of the second hydration shell with increasing pressure via generation of interstitial water within locally tetrahedral hydrogen-bonding environments.
A machine learning–based framework for mapping hydrogen at the atomic scale
Authors: Zhao Qingkun , Zhu Qi , Zhang Zhenghao , Yin Binglun , Gao Huajian , Zhou Haofei
Published: September 2024

Hydrogen, the lightest and most abundant element in the universe, plays essential roles in a variety of clean energy technologies and industrial processes. For over a century, it has been known that hydrogen can significantly degrade the mechanical properties of materials, leading to issues like hydrogen embrittlement. A major challenge that has significantly limited scientific advances in this field is that light atoms like hydrogen are difficult to image, even with state-of-the-art microscopic techniques. To address this challenge, here, we introduce Atom-H, a versatile and generalizable machine learning–based framework for imaging hydrogen atoms at the atomic scale. Using a high-resolution electron microscope image as input, Atom-H accurately captures the distribution of hydrogen atoms and local stresses at lattice defects, including dislocations, grain boundaries, cracks, and phase boundaries. This provides atomic-scale insights into hydrogen-governed mechanical behaviors in metallic materials, including pure metals like Ni, Fe, Ti and alloys like FeCr. The proposed framework has an immediate impact on current research into hydrogen embrittlement and is expected to have far-reaching implications for mapping “invisible” atoms in other scientific disciplines.
The surface interface and swimming motility influence surface-sensing responses in
Pseudomonas aeruginosa
Authors: Zheng Xuhui , Gomez-Rivas Emma J. , Lamont Sabrina I. , Daneshjoo Katayoun , Shieh Angeli , Wozniak Daniel J. , Parsek Matthew R.
Published: September 2024

Bacterial biofilms have been implicated in several chronic infections. After initial attachment, a critical first step in biofilm formation is a cell inducing a surface-sensing response. In the Gram-negative opportunistic pathogen
Pseudomonas aeruginosa
, two second messengers, cyclic diguanylate monophosphate (c-di-GMP) and cyclic adenosine monophosphate (cAMP), are produced by different surface-sensing mechanisms. However, given the disparate cellular behaviors regulated by these second messengers, how newly attached cells coordinate these pathways remains unclear. Some of the uncertainty relates to studies using different strains, experimental systems, and usually focusing on a single second messenger. In this study, we developed a tricolor reporter system to simultaneously gauge c-di-GMP and cAMP levels in single cells. Using PAO1, we show that c-di-GMP and cAMP are selectively activated in two commonly used experimental systems to study surface sensing. By further examining the conditions that differentiate a c-di-GMP or cAMP response, we demonstrate that an agarose–air interface activates cAMP signaling through type IV pili and the Pil-Chp system. However, a liquid–agarose interface favors the activation of c-di-GMP signaling. This response is dependent on flagellar motility and correlated with higher swimming speed. Collectively, this work indicates that c-di-GMP and cAMP signaling responses are dependent on the surface context.
LeviLabs: learning about sound through acoustic levitation
Authors: Johansson Andreas , Kilde-Westberg Sebastian , Enger Jonas
Published: September 2024

Sound waves are often studied as part of mechanical waves in the upper-secondary and undergraduate physics curricula. Acoustic levitation is an application of standing-wave phenomena, growing in popularity through the recent adoption of low-cost ultrasound transducers. Nevertheless, acoustic levitation has not yet been included in the standard phenomena investigated in undergraduate and upper-secondary physics courses. The objective of this Frontline is to introduce acoustic levitation in the classroom. This is done with LeviLab, a low-cost and easy-to-use experiment, accompanied by three hands-on procedures (LeviLabs): modifying the cavity length, visually representing standing waves with multiple levitated particles, and a tactile experience by moving a single particle between nodes. The first procedure yields the most accurate speed of sound measurements, while the second and third offer valuable qualitative insights into standing wave properties. This work demonstrates the educational potential of acoustic levitation to investigate sound waves. It aims to make the phenomenon accessible as a learning resource for upper-secondary and undergraduate physics laboratories by providing engaging hands-on experiences for qualitative and quantitative exploration.
Picosecond laser with Yb-doped tapered low birefringent double clad fiber
Authors: Kozlov A S , Mayzel A V , Medvedev A V , Motorin E A , Savelyev E A , Temkina V S , Filippov V N , Chamorovskiy Y K
Published: September 2024

In this study, we present results of development fiber picosecond laser by using an active ytterbium tapered double clad optical fiber with mode field diameter of 35 μm and low intrinsic birefringence (1.45 * 10−8 rad m−1). We have demonstrated 1040 nm/50 ps optical source with tunable repetition rate (within range of 1–20 MHz) and an average power of 160 W (peak power 160 kW, 8 μJ per pulse) delivering Gaussian beam with excellent quality (M
2 ∼ 1.11/1.22).
Continuous rapid fabrication of fluffy ceramic sponge with high thermomechanical properties for battery pack runaway protection
Authors: Feng Yan , Li Xinyu , Yan Jianhua
Published: September 2024

The large-scale application of power batteries has brought a huge demand for lightweight fireproof and heat insulation aerogels. However, the discontinuous processing techniques for aerogels increase synthesis costs and inhibit large-scale manufacture. Here, we propose a self-templated curl-stacking electrospinning method to directly synthesize mechanically resilient fluffy ceramic fiber sponges (FCFSs) without using polymer templates, which simultaneously have amazing thermal-mechanical and thermal insulation properties under extreme conditions. The FCFSs have a low mass density (5.49 mg/cm3). This small thermal conductivity is 0.026 W/m·K, and has a high compression stability, and therefore has good potential in battery packs’ thermal runaway protection.
A 3D photon-to-digital converter readout for low-power and large-area applications
Authors: Rossignol T. , Roy N. , Parent S. , Deslandes K. , Nolet F. , Charlebois S.A. , Pratte J.-F.
Published: September 2024

A new trend in large area noble liquid experiments is to
measure the scintillation light with photodetectors and their
electronics inside the active volume. Compared to the typical
approach of using silicon photomultipliers (SiPM) with an analog
readout chain leading to an analog-to-digital converter, this paper
presents a new 3D photon-to-digital converter (PDC) readout that
takes advantage of the binary nature of the single-photon avalanche
diodes (SPAD). The readout contains 4096 pixels over 25 mm2,
each including a 3D bonding pad and a quenching circuit. The
readout features three different outputs: a fast flag to get the
timestamp of each event from an external time-to-digital converter,
a digital sum to retrieve the number of pixels triggered during an
event, and an analog monitor to generate an analog SiPM-like output.
The analog monitor is also used to validate the two former digital
outputs. The readout also includes 61 2D CMOS SPADs for validation
purpose prior to the final 3D integration with SPADs custom made
according to our design by Teledyne DALSA (Bromont, Canada). As a
first system integration toward large-area detector applications, a
mini-tile of 2 × 2 readouts has been developed to test all
the functionalities. The measured single-photon timing resolution
ranges from 72 to 93 ps FWHM across the mini-tile SPAD channels
population (i.e. 4 × 61 channels). The flag timing
resolution is below 95 ps RMS, which includes the contribution of
the optimized flag H-tree but also an additional trigger tree that
replaces the 3D SPAD array at this stage of development. Once
bonded with the 3D SPADs, the trigger tree won't be required to
measure the flag timing resolution. With the removed contribution
of the trigger tree, the estimated flag timing resolution should be
below 45 ps RMS. The extent of the benefits of the digital sum
output depend on the application, and this paper focuses on two
cases. First, a low-power coincidence scheme such as required by
the nEXO liquid xenon experiment, leading to a power consumption as
low as 140 μW per PDC. With a finer sampling of the
scintillation light such as required for pulse shape discrimination
in liquid argon, the power consumption remains below 100 μW
per PDC. Overall, this readout is designed as a replacement for a
typical analog SiPM chain, without compromise on the performances.
ETROC1: the first full chain precision timing prototype ASIC for CMS MTD endcap timing layer upgrade
Authors: Huang X. , Sun Q. , Gong D. , Gwak P. , Kim D. , Lee J. , Liu C. , Liu T. , Liu T. , Los S. , Miryala S. , Nanda S. , Olsen J. , Sun H. , Wu J. , Ye J. , Ye Z. , Zhang L. , Zhang W.
Published: September 2024

We present the design and characterization of the first full
chain precision timing prototype ASIC, named ETL Readout Chip
version 1 (ETROC1) for the CMS MTD endcap timing layer (ETL)
upgrade. The ETL utilizes Low Gain Avalanche Diode (LGAD) sensors to
detect charged particles, with the goal to achieve a time resolution
of 40–50 ps per hit, and 30–40 ps per track with hits from two
detector layers. The ETROC1 is composed of a 5 × 5 pixel
array and peripheral circuits. The pixel array includes a
4 × 4 active pixel array with an H-tree shaped network
delivering clock and charge injection signals. Each active pixel is
composed of various components, including a bump pad, a charge
injection circuit, a pre-amplifier, a discriminator, a
digital-to-analog converter, and a time-to-digital converter. These
components play essential roles as the front-end link in processing
LGAD signals and measuring timing-related information. The
peripheral circuits provide clock signals and readout
functionalities. The size of the ETROC1 chip is
7 mm× 9 mm. ETROC1 has been fabricated in a 65 nm
CMOS process, and extensively tested under stimuli of charge
injection, infrared laser, and proton beam. The time resolution of
bump-bonded ETROC1 + LGAD chipsets reaches 42–46 ps per hit in the
beam test.
Effect of gamma-radiation on the transmission and return losses of FC/APC connectors
Authors: Gusarov A. , Dandu P. , Wuilpart M.
Published: September 2024

The Fibre Optics Current Sensor (FOCS) installed at ITER will use optical fibres to perform plasma current measurements based on the Faraday effect. A connection between the sensing fibre placed on the Vacuum Vessel and the fibre guiding the signal to the data-acquisition hardware will be required. Because of practical reasons, this link contains FC/APC connectors, which guarantee the low return loss required for normal operation of the FOCS. The connectors will be located in the port cell area and will be subject to high levels of nuclear radiation. Radiation may influence both transmission and return losses of the FC/APC connectors and, as a result, degrade the FOCS performance. To address the problem, several FC/APC connectors were exposed to Co60 gamma radiation up to a 550 kGy dose. Transmission through the connectors was monitored during irradiation. The return loss of mated FC/APC connectors was measured before and after irradiation. It was found that radiation-induced changes of both transmission and reflection parameters are acceptable for the FOCS at ITER.
Dynamic fringe field effect of the rapid ramping quadrupole magnets at a Rapid Cycling Synchrotron
Authors: Chen Jianliang , Xu Shouyan , Lu Xiaohan , Li Yong , An Yuwen , Huang Mingyang , Wang Sheng
Published: September 2024

For a DC quadrupole magnet, the normalized magnetic field
distribution along the beam trajectory is mainly determined by the
mechanical structure of the magnet and remains almost independent of
the exciting current. However, the magnetic field measurement
results of the Rapid Cycling Synchrotron (RCS) at the China
Spallation Neutron Source (CSNS) show that the normalized magnetic
field distribution along the beam trajectory varies during the
exciting current ramping process for rapid ramping
magnets. Consequently, for rapid ramping quadrupole magnets, there
are significant differences between the dynamic and static magnetic
field gradient distribution. And the changes in the distribution of
the magnetic field gradient can cause time dependent tune-shifts
during the exciting current ramping process. For RCS, the tune is
crucial, and the shifts of tune may lead to the beam approaching the
resonance line, thereby causing beam loss. The impact of the fringe
field effect of the rapid ramping quadrupole magnets on beam
dynamics at CSNS-RCS was detailly studied. A new method for
correcting the time-dependent tune shifts caused by the dynamic
field distribution, based on waveform compensation at the quadrupole
magnets, has also been proposed for the RCS of CSNS. Related
simulation and experiment have been conducted, and the simulation
results and experimental results are consistent with theoretical
study results.
Mathematical model of the spread of a pandemic like COVID-19
Authors: Sergeev A. , Khachatryan A. , Khachatryan Kh.
Published: September 2024

Using the example of the infectious disease called COVID-19, a mathematical model of the spread of a pandemic is considered. The virus that causes this disease emerged at the end of 2019 and spread to most countries around the world over the next year. A mathematical model of the emerging pandemic, called the SEIR-model (from the English words susceptible, exposed, infected, recovered), is described by a system of four ordinary dynamical equations given in §1.

The indicated system is reduced to a nonlinear integral equation of Hammerstein–Volterra type with an operator that does not have the property of monotonicity. In §3, we prove a theorem on the existence and uniqueness of a non-negative, bounded and summable solution of this system.

Based on real data on the COVID-19 disease in France and Italy, given in §2, numerical calculations are performed showing the absence of a second wave for the obtained solution.
On a class of degenerate hypoelliptic polynomials
Authors: Kazaryan H. , Margaryan V.
Published: September 2024

This work is devoted to finding conditions on “lower-order terms”, the addition of which does not violate the hypoellipticity of a given operator (of the characteristic polynomial of this operator). Necessary and sufficient conditions for the hypoellipticity of “two-layered polynomials” are obtained. In terms of comparing strength, power, and the upper bound of the ratio of comparable polynomials, conditions are obtained under which the added polynomials preserve the hypoellipticity of the original polynomial. Examples are given that illustrate the obtained results.
Conventional and 2-Dimensional Speckle Tracking Echocardiography in Fabry Disease
Authors: Yu Yang , Wang Chonghui , Wang Han , Yang Ying , Liu Lin , Fan Fangfang , Zhao Ya-wen , Zhang Wei , Ma Wei
Published: September 2024

OBJECTIVE

To analyze the myocardial involvement and explore the strain characteristics of the left atrium and the left ventricle in patients with Fabry disease (FD) using conventional echocardiography and 2-dimensional speckle tracking echocardiography (2D-STE).

METHODS

A retrospective study was conducted. Sixty-nine patients with FD who were treated in the Department of Cardiology, Neurology and Nephrology of Peking University First Hospital from August 2014 to February 2023 and underwent echocardiography examination in the Cardiology Department were collected (FD group). During the same time, 69 age- and sex-matched individuals who had no cardiovascular, cerebrovascular, renal, metabolic, and autoimmune diseases, and had no obvious abnormalities on echocardiography were included in the control group. The clinical data and laboratory tests were collected, and routine echocardiography and 2D-STE were performed to analyze left atrial strain and left ventricular longitudinal strain. The differences in relevant parameters between groups were compared.

RESULTS

Compared with the control group, the patients in the FD group had smaller body mass index and body surface area, slower heart rate, poorer estimated glomerular filtration rate, and significantly increased brain natriuretic peptide and cardiac troponin I (all P < 0.05). E’med in the FD group was reduced (8.4 ± 3.4 vs. 9.9 ± 2.8, P = 0.006) and E peak, E peak deceleration time, pulmonary artery systolic pressure increased, interventricular septum and left ventricular posterior wall thickened, left ventricular mass index, and early diastolic transmitral inflow velocity/septal mitral annular velocity (E/Eʹ) increased (all P < 0.05). Compared with the control group, left atrial strains [including left atrial strain during reservoir phase (LASr), left atrial strain during contraction phase (LASct), left atrial strain during conduit phase (LAScd)] and left ventricular average global longitudinal strain (GLSavg) were reduced in the FD group. In the segmental longitudinal strain of the left ventricular, the strain was significantly reduced except for the strain of the basal and middle segment of the inferior wall (P < 0.05).

CONCLUSIONS

Patients with FD usually have multisystem involvement such as kidney and heart. Echocardiography usually shows varying degrees of myocardial hypertrophy and diastolic dysfunction, while left ventricular ejection fraction is normal. Left atrial strain, left ventricular global, and segmental longitudinal strain are all decreased to varying degrees.
Using the Montgomery–Koyama–Smith equation to calculate the stomatal area per unit lamina area for 12 Magnoliaceae species
Authors: Yan Chunxiu , Shi Peijian , Yu Kexin , Guo Xuchen , Lian Meng , Miao Qinyue , Wang Lin , Yao Weihao , Zheng Yiwen , Zhu Fuyuan , Niklas Karl J
Published: September 2024

Background and Aims

The Montgomery–Koyama–Smith (MKS) equation predicts that total leaf area per shoot is proportional to the product of the sum of individual leaf widths and maximum individual leaf length, which has been validated for some herbaceous and woody plants. The equation is also predicted to be valid in describing the relationship between the total stomatal area per micrograph (AT) and the product of the sum of individual stomatal widths (denoted as LKS) and maximum individual stomatal length (denoted by WKS) in any particular micrograph.

Methods

To test the validity of the MKS equation, 69 931 stomata (from 720 stomatal micrographs from 12 Magnoliaceae species) were examined. The area of each stoma was calculated using empirical measurements of stomatal length and width multiplied by a constant. Six equations describing the relationships among AT, LKS and WKS were compared. The root mean square (RMSE) and the Akaike information criterion (AIC) were used to measure the goodness of fit and the trade-off between the goodness of fit and the structural complexity of each model, respectively.

Key Results

Analyses supported the validity of the MKS equation and the power-law equation AT ∝ (LKSWKS)α, where α is a scaling exponent. The estimated values of α at the species level and for the pooled data were all statistically smaller than unity, which did not support the hypothesis that AT ∝ LKSWKS. The power-law equation had smaller RMSE and AIC values than the MKS equation for the data from the 12 individual species and the pooled data.

Conclusions

These results indicate that AT tends to scale allometrically with LKSWKS, and that increases in AT do not keep pace with increases in LKSWKS. In addition, using LKSWKS is better than using only one of the two variables to calculate AT.
Post-selection inference in regression models for group testing data
Authors: Shen Qinyan , Gregory Karl , Huang Xianzheng
Published: September 2024

We develop a methodology for valid inference after variable selection in logistic regression when the responses are partially observed, that is, when one observes a set of error-prone testing outcomes instead of the true values of the responses. Aiming at selecting important covariates while accounting for missing information in the response data, we apply the expectation-maximization algorithm to compute maximum likelihood estimators subject to LASSO penalization. Subsequent to variable selection, we make inferences on the selected covariate effects by extending post-selection inference methodology based on the polyhedral lemma. Empirical evidence from our extensive simulation study suggests that our post-selection inference results are more reliable than those from naive inference methods that use the same data to perform variable selection and inference without adjusting for variable selection.
Biallelic PTPMT1 variants disrupt cardiolipin metabolism and lead to a neurodevelopmental syndrome
Authors: Falabella Micol , Pizzamiglio Chiara , Tabara Luis Carlos , Munro Benjamin , Abdel-Hamid Mohamed S , Sonmezler Ece , Macken William L , Lu Shanti , Tilokani Lisa , Flannery Padraig J , Patel Nina , Pope Simon A S , Heales Simon J R , Hammadi Dania B H , Alston Charlotte L , Taylor Robert W , Lochmuller Hanns , Woodward Cathy E , Labrum Robyn , Vandrovcova Jana , Houlden Henry , Chronopoulou Efstathia , Pierre Germaine , Maroofian Reza , Hanna Michael G , Taanman Jan-Willem , Hiz Semra , Oktay Yavuz , Zaki Maha S , Horvath Rita , Prudent Julien , Pitceathly Robert D S
Published: September 2024

Primary mitochondrial diseases (PMDs) are among the most common inherited neurological disorders. They are caused by pathogenic variants in mitochondrial or nuclear DNA that disrupt mitochondrial structure and/or function, leading to impaired oxidative phosphorylation (OXPHOS). One emerging subcategory of PMDs involves defective phospholipid metabolism. Cardiolipin, the signature phospholipid of mitochondria, resides primarily in the inner mitochondrial membrane, where it is biosynthesized and remodelled via multiple enzymes and is fundamental to several aspects of mitochondrial biology. Genes that contribute to cardiolipin biosynthesis have recently been linked with PMD. However, the pathophysiological mechanisms that underpin human cardiolipin-related PMDs are not fully characterized.

Here, we report six individuals, from three independent families, harbouring biallelic variants in PTPMT1, a mitochondrial tyrosine phosphatase required for de novo cardiolipin biosynthesis. All patients presented with a complex, neonatal/infantile onset neurological and neurodevelopmental syndrome comprising developmental delay, microcephaly, facial dysmorphism, epilepsy, spasticity, cerebellar ataxia and nystagmus, sensorineural hearing loss, optic atrophy and bulbar dysfunction. Brain MRI revealed a variable combination of corpus callosum thinning, cerebellar atrophy and white matter changes.

Using patient-derived fibroblasts and skeletal muscle tissue, combined with cellular rescue experiments, we characterized the molecular defects associated with mutant PTPMT1 and confirmed the downstream pathogenic effects that loss of PTPMT1 has on mitochondrial structure and function. To further characterize the functional role of PTPMT1 in cardiolipin homeostasis, we created a ptpmt1 knockout zebrafish. This model had abnormalities in body size, developmental alterations, decreased total cardiolipin levels and OXPHOS deficiency.

Together, these data indicate that loss of PTPMT1 function is associated with a new autosomal recessive PMD caused by impaired cardiolipin metabolism, highlighting the contribution of aberrant cardiolipin metabolism towards human disease and emphasizing the importance of normal cardiolipin homeostasis during neurodevelopment.
Incorporation of ESIPT into pillar[5]arene for solid-state dual emission responsive to n-hexane vapor
Authors: Kaneda Tomoya , Kato Kenichi , Ohtani Shunsuke , Ogoshi Tomoki
Published: September 2024

Pillar[5]arene is a promising macrocyclic receptor of a chemical sensor showing shape-selective encapsulation of neutral molecules into the cavity, but the poor fluorescence properties remain a challenge. Herein, we report a pillar[5]arene coupled with 2-(2-hydroxyphenyl)benzoxazole (HBO), which displays bright fluorescence in both solution and the solid state. Owing to the excited-state intramolecular proton transfer (ESIPT) in the HBO moiety, greatly improved fluorescence is observed for the pillar[5]arene derivative in CHCl3 (Φlum = 11%) and powder form (Φlum = 25%). Moreover, the emission color changes from light green to blue when the powder sample is exposed to n-hexane vapor. The color change derives from variable dual emission via ESIPT and excimer-forming pathways, as suggested by fluorescence lifetime measurements at different wavelengths. Powder x-ray diffraction indicates that increased crystallinity and a small alteration in the solid-state structure leads to visible fluorescent chromism upon vapor encapsulation.