bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterizing and predicting the partial slip subjected to variable gradients of velocity and pressure in eccentric micro-scale Taylor–Couette flows
Authors: Sun Yi-jian , Lyu Yuan-wei , Zhang Jing-yang , Zhao Qijun , Zhao Dan
Published: October 2024

In the context of eccentric micro-scale Taylor–Couette flow, variations in localized flow scales result in a non-uniform fluid–solid interface slip state, distinct from the typically studied uniform slip velocity distribution. This study introduces a boundary condition definition method aimed at characterizing partial slip states, complemented by a coupled iterative analysis system tailored to address this complexity. Key contributions include the development of a method for calculating the limiting shear stress, which considers local velocity gradients and pressures. Validation demonstrates that the locally derived slip state aligns more closely with Knudsen number distributions of local flow scales compared to traditional uniform slip models, and exhibits greater consistency with experimentally measured pressure distributions. Additionally, the study reveals that eccentric Taylor–Couette flow, characterized by significant variations in local flow scales and strong self-induced pressure effects, leads to complex distributions of local pressure, velocity gradients, and differences in local slip velocities. Specifically, the non-uniform distribution of local pressure gradients due to eccentricity results in partial slip occurring predominantly on the rotor in regions with positive pressure gradients, and on the stator in regions with negative pressure gradients. Furthermore, the variation in gap height exerts a greater influence on local slip compared to rotational speed and eccentricity ratio. Under certain conditions influenced by pressure gradients, the slip velocity on the rotor may exceed its tangential speed.
Development of a space-compatible packaging system for an integrated monolithic ultra-stable optical reference
Authors: Zhan Zhenhai , Luo Yingxin , Yeh Hsien-Chi , Li Hongyin , Chen Weilu , Ren Chongzhi , Zeng Bingcheng
Published: October 2024

We report the development of a space-compatible packaging system for an integrated monolithic ultra-stable optical reference toward China’s next-generation geodesy mission with low orbit satellite-to-satellite tracking. Building on our previous work, we optimized the mounting structure and thermal insulation mechanism using the finite element method. The comprehensive simulation results demonstrated the robustness of the entire packaging system with enough margins to withstand severe launch loads and maintain an ultra-high geometric cavity length stability. A long-term prediction of the vacuum maintenance around the cavity during in-orbit operation was conducted. An engineering prototype, within which an integrated monolithic optical reference has been mounted, was built based on our optimized design, and it has successfully passed typical aerospace environmental tests, including sinusoidal vibration (∼10 g, 10–100 Hz), random vibration (∼0.045 g2/Hz, 10–2000 Hz), and thermal cycling (0–45, 3 °C/min, lasting for 90 h). The experimental thermal time constant of the prototype exceeded 9.5 × 104 s, enabling a temperature stability of 1.1 × 10−6 K/Hz1/2 at 10 mHz on the optical cavity, with external active temperature control. The design is also suitable and useful for laboratory and terrestrial applications.
In-plane orientational motions of the functional groups of molecules at the air/water interface by time-resolved vibrational sum frequency generation
Authors: Huang-Fu Zhi-Chao , Zhang Tong , Brown Jesse B. , Qian Yuqin , Fisher Haley , Rao Yi
Published: October 2024

The movements of molecules at interfaces and surfaces are restricted by their asymmetric environments, leading to anisotropic orientational motions. In this work, in-plane orientational motions of the –C=O and –CF3 groups of coumarin 153 (C153) at the air/water interface were measured using time-resolved (TR) vibrational sum frequency generation (SFG). The in-plane orientational time constants of the –C=O and –CF3 groups of C153 are found to be 41.5 ± 8.2 and 36.0 ± 4.5 ps. These values are over five-times faster than that of 198 ± 15 ps for the permanent dipole of the whole C153 molecule at the interface, which may indicate that the two groups experience different interfacial friction in the plane. These differences could also be the result of the permanent dipole of C153 being almost five times those of the –C=O and –CF3 groups. The difference in orientational motions reveals the microscopic heterogeneous environment that molecules experience at the interface. While the interfacial dynamics of the two functional groups are similar, our TR-SFG experiments allowed the quantification of the in-plane dynamics of individual functional groups for the first time. Our experimental findings about the interfacial molecular motion have implications for molecular rotations, energy transfer, and charge transfer at material interfaces, photocatalysis interfaces, and biological cell/membrane aqueous interfaces.
Application of a non-intrusive reduced order modeling approach to magnetohydrodynamics
Authors: Lo Verso M. , Riva S. , Introini C. , Cervi E. , Giacobbo F. , Savoldi L. , Di Prinzio M. , Caramello M. , Barucca L. , Cammi A.
Published: October 2024

Magnetohydrodynamics (MHD) investigates the intricate relationship between electromagnetism and fluid dynamics, offering a complete insight into the behavior of conducting fluids under the influence of magnetic fields. This theory plays a pivotal role in the framework of magnetic confinement fusion, where it can be applied to describe both thermonuclear plasmas confined inside the vacuum vessel and operating fluids, such as liquid metals and molten salts, flowing within the blanket of future tokamaks. Currently, the state-of-the-art numerical modeling of MHD scenarios employs a multi-physics framework to examine the interplay between magnetic fields and thermal hydraulics; however, due to the complexity of the involved physics, detailed models are required, resulting in a significant computational burden. In this regard, reduced order modeling (ROM) techniques may represent a promising solution, as they enable approximating complex systems with lower-dimensional models. Indeed, ROM methodologies can significantly reduce the required computational time while maintaining accuracy in capturing the convoluted physics involved in fusion reactors, especially in the contexts of sensitivity analysis, uncertainty quantification, and control. Despite their potential, ROM methods are relatively under-explored within the MHD framework; this study applies ROM techniques to MHD scenarios, focusing on their capabilities and possible limitations. To this aim, the backward-facing step, which is well suited for exploring the effects of different magnetic fields on turbulent dynamics, is adopted as case study. In particular, this work evaluates the potentialities of the ROM approach in enhancing computational efficiency within the MHD domain. Each of the methods evaluated was effective in precisely reconstructing flow dynamics at any given time and across the full range of magnetic field values tested while significantly reducing computational costs compared to full-order simulations. Practically, this study demonstrates the feasibility to create simplified models that accurately represent the magnetohydrodynamic flows of fluids within the blanket.
Field-free spin–orbit torque magnetization switching in Pt/CoTb devices grown on flexible substrates for neuromorphic computing
Authors: Wang Wei , Feng Chuanwei , Wang Yiheng , Huang Qikun , Wang Dong , Fan Yibo , Han Xiang , Bai Lihui , Chen Yanxue , Tian Yufeng , Yan Shishen
Published: October 2024

Flexible spintronic devices based on spin–orbit torque (SOT)-induced perpendicular magnetization switching (PMS) have attracted increasing attention due to their high storage intensity and good programming capability. However, to achieve deterministic PMS, an in-plane auxiliary magnetic field is required, which greatly limits its application. Here, we show that “robust” magnetic field-free SOT-driven PMS is realized in the oblique sputtered Pt/CoTb multilayers grown on a flexible polyimide substrate. “Robust” means the magnetic field-free SOT switching is highly repeatable and stable after 100 bending cycles under various bending conditions. Additionally, the fabricated flexible multilayers exhibit nearly linear and nonvolatile multistate plasticity as synapses and a nonlinear sigmoid activation function when acting as neurons. We construct a fully connected neural network for handwritten digit recognition, achieving an over 96.27% recognition rate. Our findings may spur further investigations on the SOT-based flexible spintronic devices for wearable artificial intelligence applications.
Perspectives on local thermal non-equilibrium (LTNE) Darcy–Bénard convection: Variable permeability and viscosity effects
Authors: Latha N. , Shankar B. M. , Naveen Kumar S. B. , Shivakumara I. S.
Published: October 2024

The interplay between variations in permeability and viscosity on the onset of local thermal non-equilibrium in Darcy–Bénard convection has been investigated. Specifically, permeability is modeled as decreasing linearly with depth, while viscosity decreases exponentially. The validity of the principle of exchange of stabilities is confirmed. A linear instability analysis of the quiescent state is conducted through normal mode decomposition of disturbances, with threshold values for instability onset computed numerically using the Galerkin method. The individual and combined effects of increasing the variable permeability and viscosity parameters on the instability characteristics of the system are examined in detail, highlighting both commonalities and distinctions. It is observed that increasing each parameter individually hastens the onset of convection. However, their combined influence produces both stabilizing and destabilizing effects under certain parametric conditions. In all scenarios, an increase in the scaled interphase heat transfer coefficient consistently delays the onset of convection, whereas a higher ratio of porosity-modified conductivities has the opposite effect. Furthermore, the size of the convection cells remains unchanged at the extreme values of the scaled interphase heat transfer coefficient.
An analytical heat transfer model for transient Raman thermometry analysis
Authors: Yu Taocheng , Fu Yilu , Fu Chenguang , Zhu Tiejun , Ong Wee-Liat
Published: October 2024

Transient Raman thermometry improves on its steady-state counterpart by eliminating the error-prone steps of temperature calibration and laser absorption measurement. However, the accompanying complex heat transfer process often requires numerical analysis, such as the finite element method, to decipher the measured data. This step can be time-consuming, inconvenient, and difficult to derive a physical understanding of the heat transfer process involved. In this work, the finite element method is replaced by fitting the measured data to an analytical three-dimensional heat transfer model. This process can be completed in a few seconds. Using this approach, the in-plane thermal conductivity of two bulk layered materials and the interfacial thermal conductance between two-dimensional materials and quartz have been successfully measured. Based on our model, we performed an analytical quantitative sensitivity analysis for transient Raman thermometry to discover new physical insights. The sensitivity of the in-plane thermal conductivity of bulk layered materials is dictated by the ratio between the spot radius and heat spreading distance. The sensitivity of the interfacial thermal conductance between two-dimensional materials and quartz is determined by its conductance value. In addition, the uncertainty of the measured value contributed by the uncertainty of the input parameters can be efficiently estimated using our model. Our model provides an efficient data and sensitivity analysis method for the transient Raman thermometry technique to enable high throughput measurements, facilitate designing experiments, and derive physical interpretations of the heat transfer process.
Thermal diffusivity measurement of polymer microfibers while eliminating the effect of heat radiation
Authors: Hamasaki Hiromu , Mochizuki Takumi , Shibata Ryosuke , Suzuki Hayate , Ikeda Hiroya
Published: October 2024

The thermal transport properties of polymer fibers are important for heat dissipation in apparel, matrix of wearable devices, and so on. However, it is difficult to precisely determine the thermal properties of a single polymer fiber because of non-negligible thermal radiation due to its relatively low thermal conductivity and high surface-area-to-volume ratio. Here, we developed a system in which the apparent thermal diffusivity and size of microfibers can be measured to estimate their intrinsic thermal diffusivity. We determined the thermal diffusivities of three fibrous materials: silk, spider silk, and cellulose microfibers to be 4.2 (±0.8)×10−7, 1.8 (±0.7)×10−7, and 4.7 (±0.5)×10−7, respectively. For all fibers, the apparent thermal diffusivity strongly depended on the fiber size, indicating that eliminating the radiation effect is indispensable for determining the thermal transport properties of polymer microfibers.
SnotWatch: data collaboration informing disease impact
Authors: Buttery Jim P. , Weinman Aaron L. , Sawires Rana , Zhao Eric , Quan Nguyen Tu , Clothier Hazel J. ,   on behalf of the SnotWatch Collaboration Group
Published: October 2024

The spectrum of health conditions associated with the circulation of respiratory viruses remains poorly quantified. The SnotWatch platform has established a databank containing test results for respiratory polymerase chain reaction tests conducted by eight major Victorian pathology laboratories and has obtained access to major healthcare presentation databases, such as the Victorian Admitted Episodes Dataset, Victorian Emergency Minimum Dataset and POLAR GP. By establishing a statistical approach to describe the associations between healthcare presentations and circulating viruses in space and time at a population level, SnotWatch is uncovering the health conditions associated with virus circulation. SnotWatch’s methods have been validated by demonstrating the capacity to describe well-known associations, but have also uncovered novel associations. Methods used have also been able to incorporate environmental exposures. By elucidating the associations between viruses and health conditions, SnotWatch allows clinicians to make better informed diagnoses, anticipate healthcare presentations and outcomes, optimises resource management by healthcare providers and allows the benefits of vaccination to be more fully appreciated. SnotWatch’s future includes establishing methods for attributable burden, developing models for nowcasting and deepening our understanding of the economic impact of viruses.
Open ocean convection drives enhanced eastern pathway of the glacial Atlantic Meridional Overturning Circulation
Authors: Gu Sifan , Liu Zhengyu , Ng Hong Chin , Lynch-Stieglitz Jean , McManus Jerry F. , Spall Michael , Jahn Alexandra , He Chengfei , Li Lingwei , Yan Mi , Wu Lixin
Published: October 2024

Abundant proxy records suggest a profound reorganization of the Atlantic Meridional Overturning Circulation (AMOC) during the Last Glacial Maximum (LGM, ~21,000 y ago), with the North Atlantic Deep Water (NADW) shoaling significantly relative to the present-day (PD) and forming Glacial North Atlantic Intermediate Water (GNAIW). However, almost all previous observational and modeling studies have focused on the zonal mean two-dimensional AMOC feature, while recent progress in the understanding of modern AMOC reveals a more complicated three-dimensional structure, with NADW penetrating from the subpolar North Atlantic to lower latitude through different pathways. Here, combining
231
Pa/
230
Th reconstructions and model simulations, we uncover a significant change in the three-dimensional structure of the glacial AMOC. Specifically, the mid-latitude eastern pathway (EP), located east of the Mid-Atlantic Ridge and transporting about half of the PD NADW from the subpolar gyre to the subtropical gyre, experienced substantial intensification during the LGM. A greater portion of the GNAIW was transported in the eastern basin during the LGM compared to NADW at the PD, resulting in opposite
231
Pa/
230
Th changes between eastern and western basins during the LGM. Furthermore, in contrast to the wind-steering mechanism of EP at PD, the intensified LGM EP was caused primarily by the rim current forced by the basin-scale open-ocean convection over the subpolar North Atlantic. Our results underscore the importance of accounting for three-dimensional oceanographic changes to achieve more accurate reconstructions of past AMOC.
A novel
N
4,
N
4-dimethylcytidine in the archaeal ribosome enhances hyperthermophily
Authors: Fluke Kristin A. , Dai Nan , Wolf Eric J. , Fuchs Ryan T. , Ho P. Shing , Talbott Victoria , Elkins Liam , Tsai Yueh-Lin , Schiltz Jackson , Febvre Hallie P. , Czarny Ryan , Robb G. Brett , Corrêa Ivan R. , Santangelo Thomas J.
Published: October 2024

Ribosome structure and activity are challenged at high temperatures, often demanding modifications to ribosomal RNAs (rRNAs) to retain translation fidelity. LC-MS/MS, bisulfite-sequencing, and high-resolution cryo-EM structures of the archaeal ribosome identified an RNA modification,
N
4,
N
4-dimethylcytidine (m
4
2
C), at the universally conserved C918 in the 16S rRNA helix 31 loop. Here, we characterize and structurally resolve a class of RNA methyltransferase that generates m
4
2
C whose function is critical for hyperthermophilic growth. m
4
2
C is synthesized by the activity of a unique family of RNA methyltransferase containing a Rossman-fold that targets only intact ribosomes. The phylogenetic distribution of the newly identified m
4
2
C synthase family implies that m
4
2
C is biologically relevant in each domain. Resistance of m
4
2
C to bisulfite-driven deamination suggests that efforts to capture m
5
C profiles via bisulfite sequencing are also capturing m
4
2
C.
Reverse development in the ctenophore
Mnemiopsis leidyi
Authors: Soto-Angel Joan J. , Burkhardt Pawel
Published: October 2024

Reverse development, or the ability to rejuvenate by morphological reorganization into the preceding life cycle stage is thought to be restricted to a few species within Cnidaria. To date,
Turritopsis dohrnii
is the only known species capable of undergoing reverse development after the onset of sexual reproduction. Here, we demonstrate that the ctenophore
Mnemiopsis leidyi
is capable of reversal from mature lobate to early cydippid when fed following a period of stress. Our findings illuminate central aspects of ctenophore development, ecology, and evolution and show the high potential of
M. leidyi
as a unique model system to study reverse development and rejuvenation. Besides shedding light on the plasticity of developmental programs, these results raise fundamental questions about early animal development, body plans, and life cycles.
Phylogenetic evidence supporting the nonenveloped nature of hepadnavirus ancestors
Authors: Buigues Jaime , Viñals Adrià , Martínez-Recio Raquel , Monrós Juan S. , Cuevas José M. , Sanjuán Rafael
Published: October 2024

Reverse-transcribing animal DNA viruses include the hepadnaviruses, a well-characterized family of small enveloped viruses that infect vertebrates but also a sister group of nonenveloped viruses more recently discovered in fish and termed the nackednaviruses. Here, we describe the complete sequence of a virus found in the feces of an insectivorous bat, which encodes a core protein and a reverse transcriptase but no envelope protein. A database search identified a viral sequence from a permafrost sample as its closest relative. The two viruses form a cluster that occupies a basal phylogenetic position relative to hepadnaviruses and nackednaviruses, with an estimated divergence time of 500 My. These findings may lead to the definition of a “proto-nackednavirus” family and support the hypothesis that the ancestors of hepadnaviruses were nonenveloped.
Biochemical analysis of EGFR exon20 insertion variants insASV and insSVD and their inhibitor sensitivity
Authors: Zhao Hanchen , Beyett Tyler S. , Jiang Jie , Rana Jaimin K. , Schaeffner Ilse K. , Santana Jhasmer , Jänne Pasi A. , Eck Michael J.
Published: October 2024

Somatic mutations in the epidermal growth factor receptor (EGFR) are a major cause of non–small cell lung cancer. Among these structurally diverse alterations, exon 20 insertions represent a unique subset that rarely respond to EGFR tyrosine kinase inhibitors (TKIs). Therefore, there is a significant need to develop inhibitors that are active against this class of activating mutations. Here, we conducted biochemical analysis of the two most frequent exon 20 insertion variants, V769_D770insASV (insASV) and D770_N771insSVD (insSVD) to better understand their drug sensitivity and resistance. From kinetic studies, we found that EGFR insASV and insSVD are similarly active, but have lower K
m, ATP
values compared to the L858R variant, which contributes to their lack of sensitivity to 1st-3rd generation EGFR TKIs. Biochemical, structural, and cellular studies of a diverse panel of EGFR inhibitors revealed that the more recently developed compounds BAY-568, TAS6417, and TAK-788 inhibit EGFR insASV and insSVD in a mutant-selective manner, with BAY-568 being the most potent and selective versus wild-type (WT) EGFR. Cocrystal structures with WT EGFR reveal the binding modes of each of these inhibitors and of poziotinib, a potent but not mutantselective inhibitor, and together they define interactions shared by the mutant-selective agents. Collectively, our results show that these exon20 insertion variants are not inherently inhibitor resistant, rather they differ in their drug sensitivity from WT EGFR. However, they are similar to each other, indicating that a single inhibitor should be effective for several of the diverse exon 20 insertion variants.
IMPA1-derived inositol maintains stemness in castration-resistant prostate cancer via IMPDH2 activation
Authors: Hsu Che-Chia , Wang Guihua , Li Chien-Feng , Zhang Xian , Cai Zhen , Chen Tingjin , Pan Bo-Syong , Manne Rajesh Kumar , Deep Gagan , Gu Haiwei , Wang Yuzhuo , Peng Danni , Penugurti Vasudevarao , Zhou Xiaobo , Xu Zhigang , Chen Zhongzhu , Chen Ming , Armstrong Andrew J. , Huang Jiaoti , Li Hong-Yu , Lin Hui-Kuan
Published: October 2024

Acquisition of prostate cancer stem cells (PCSCs) manifested during androgen ablation therapy (ABT) contributes to castration-resistant prostate cancer (CRPC). However, little is known about the specific metabolites critically orchestrating this process. Here, we show that IMPA1-derived inositol enriched in PCSCs is a key metabolite crucially maintaining PCSCs for CRPC progression and ABT resistance. Notably, conditional Impa1 knockout in the prostate abrogates the pool and properties of PCSCs to orchestrate CRPC progression and prolong the survival of TRAMP mice. IMPA1-derived inositol serves as a cofactor that directly binds to and activates IMPDH2, which synthesizes guanylate nucleotides for maintaining PCSCs with ARlow/− features leading to CRPC progression and ABT resistance. IMPA1/inositol/IMPDH2 axis is upregulated in human prostate cancer, and its overexpression predicts poor survival outcomes. Genetically and pharmacologically targeting the IMPA1/inositol/IMPDH2 axis abrogates CRPC and overcomes ABT resistance in various CRPC xenografts, patient-derived xenograft (PDX) tumor models, and TRAMP mouse models. Our study identifies IMPDH2 as an inositol sensor whose activation by inositol represents a key mechanism for maintaining PCSCs for CRPC and ABT resistance.
Suppression of melanoma by mice lacking MHC-II: Mechanisms and implications for cancer immunotherapy
Authors: Shi Hexin , Medler Dawson , Wang Jianhui , Browning Rachel , Liu Aijie , Schneider Sara , Duran Bojorquez Claudia , Kumar Ashwani , Li Xiaohong , Quan Jiexia , Ludwig Sara , Moresco James J. , Xing Chao , Moresco Eva Marie Y. , Beutler Bruce
Published: October 2024

Immune checkpoint inhibitors interfere with T cell exhaustion but often fail to cure or control cancer long-term in patients. Using a genetic screen in C57BL/6J mice, we discovered a mutation in host H2-Aa that caused strong immune-mediated resistance to mouse melanomas. H2-Aa encodes an MHC class II α chain, and its absence in C57BL/6J mice eliminates all MHC-II expression. H2-Aa deficiency, specifically in dendritic cells (DC), led to a quantitative increase in type 2 conventional DC (cDC2) and a decrease in cDC1. H2-Aa–deficient cDC2, but not cDC1, were essential for melanoma suppression and effectively cross-primed and recruited CD8 T cells into tumors. Lack of T regulatory cells, also observed in H2-Aa deficiency, contributed to melanoma suppression. Acute disruption of H2-Aa was therapeutic in melanoma-bearing mice, particularly when combined with checkpoint inhibition, which had no therapeutic effect by itself. Our findings suggest that inhibiting MHC-II may be an effective immunotherapeutic approach to enhance immune responses to cancer.
Characteristics of an antistatic semiconductor bridge based on micro/nano processing techniques
Authors: Wang Lei , Zhou Bin , Tao Yuren , Wang Jun
Published: October 2024

Regarded as a novel type of igniter, semiconductor bridge (SCB) prove superior in burst time and burst energy (less than 5 mJ). Nevertheless, SCB discharged by strong electrostatic discharge (ESD) inevitably leads to damage. To enhance the electrostatic safety of the SCB initiator, an antistatic semiconductor bridge (ASCB) initiator incorporating a transient suppression (TVS) diode was fabricated based on micro/nan processing techniques. Three sizes of polysilicon bridge (10440 µm2, 17 020 µm2, and 23 760 µm2) and two breakdown voltages of TVS (7.3 V and 8.6 V) were designed. Then constant discharge test and ESD test were carried out to investigate the effects of bridge area and TVS breakdown voltage on the performance of ASCB. The results showed that, the energy density of polysilicon bridge is a linear function of the ratio of the square of the current to the area of the polysilicon (ISCB
2/A). The breakdown voltage will affect the shunt of TVS. During polysilicon heat accumulation process, owing to shunt of TVS, the energy applied to the polysilicon bridge reduced. In addition, the bridge with a larger area were more difficult to reach the explosive limit. Therefore, both the breakdown voltage of the TVS and the area of the polysilicon bridge influenced the explosive characteristics of the ASCB. The antistatic performance of ASCB is obviously stronger than that of SCB, and A2 (ASCB with bridge area of 23 760 µm2 and breakdown voltage of 7.3 V) is the strongest among the three types of ASCB. Reducing the breakdown voltage of TVS and increasing the bridge area of polysilicon can effectively improve the antistatic performance of ASCB.
Aspect ratio-dependent etching in silicon using XeF2: experimental investigation and comparative analysis with dry etching methods
Authors: Baradel Baptiste , Léon Olivier , Méry Fabien , Combette Philippe , Giani Alain
Published: October 2024

Silicon machining plays a crucial role in shaping three-dimensional structures for micro-electro-mechanical systems applications. This study investigates aspect ratio dependent etching (ARDE) across various silicon etching processes, with a particular focus on Xenon Difluoride etching, in comparison to reactive ion etching (RIE) and Deep RIE . By exploring different etching parameters, the study highlights the presence of ARDE in both plasma and non-plasma etching processes. Additionally, it is demonstrated that ARDE can be modeled by a saturating exponential function through experimental adjustment of parameters, enabling the estimation of etching profiles.
Electrohydrodynamic characteristics of a needle-to-ring positive corona discharges: self-consistent modeling and turbulence effects
Authors: Tuan Dung Nguyen , Rogier François , Kourtzanidis Konstantinos
Published: October 2024

We report on the voltage–current characteristics as well as the voltage–velocity characteristics of a needle-to-ring configuration by self-consistent, 2D-axisymmetric, multi-physics plasma-fluid simulations. Parametric studies are performed to investigate the effects of background ionization level on the plasma electrical characteristics as well as turbulence parameters on the resulting flow. Our results show that the discharge and the flow exhibit an annular structure around the needle (anode) tip, with a maximum positive ion density from

1.5
×

10

18

–2.7

×

10

18

 

m

−
3

and a maximum flow velocity from 10–15 

m

 

s

−
1

, for overvoltages between 4−12 

kV

and an anode–cathode distance of 20 

mm

. Good overall agreement with experimental findings is achieved, noting that background ionization level can be used as a tuning parameter to better match experimentally measured current values even with a simplified plasma-chemistry. A better agreement between simulation and experiments is achieved concerning the voltage–velocity curves. Therefore, the latter are likely to be better indicators for assessing and validating electrohydrodynamic effects of corona actuators through numerical modeling. The flow dynamics indicate that positive-corona-induced ionic winds are most likely laminar to turbulent transitional flows, with a ratio between eddy viscosity and air viscosity varying between

0
−
200

.
First-principles study of the electron and phonon transport properties in monolayer boron monosulfide
Authors: Song Hong-Yue , Guo Ying , Liu Dandan , Li Meng
Published: October 2024

Motivated by the excellent electronic properties of theoretical proposed monolayer boron monosulfides (BS) binary materials, which belong to a light-element member of the group IIIA chalcogenides family, we have investigated the electron and phonon transport properties of three monolayer phases of BS (α, β and γ) using first-principles and Boltzmann transport theory methods. The calculated electronic structures show that α- and β-BS are semiconductors with indirect bandgaps of 4.01 eV and 3.87 eV, respectively, whereas the γ-BS is a semiconductor with a direct bandgap of 2.97 eV. Additionally, due to their light carrier effective masses, superior high carrier mobilities are observed, thus bringing high Seebeck coefficients. We also find that due to the absence of imaginary phonon frequencies, the three monolayer phases of BS show dynamical stability. The phonon group velocity and relaxation time are also calculated to analyze the phonon thermal conductivity. We find that strong phonon scattering makes γ-BS monolayer possess extremely low phonon thermal conductivity (1.2 and 2.7 Wm−1K−1 along the x and y directions at 300 K, respectively), whereas α- and β-BS monolayers show a relatively high phonon thermal conductivity. Therefore, the highest predicted ZT value of 1.7 (

n

-type) at 700 K is obtained for monolayer γ-BS along the x direction. However, α- and β-BS monolayers have extremely low ZT values. Our results reveal that the γ-BS monolayer has wider promising applications in high performance thermoelectric material than α- and β-BS monolayers.
A 3D-printing metasurface-augmented half-circle Maxwell fisheye lens for millimetre-wave analogue beamforming
Authors: Alali Bader , Zelenchuk Dmitry , Ali Babar Abbasi Muhammad
Published: October 2024

This article presents a 2D metasurface-augmented half-circle Maxwell fisheye lens (HMFL) designed to move its focal axis to a targeted direction with a maximum elevation angle of 45∘, suitable for switchers and power division networks in the millimetre wave (mmWave) band. This metasurface-augmented beamformer enables consistent analogue performance across a bandwidth of 22–32 GHz. The proposed beamformer features a reflective metasurface consisting of

2
×
40

Phoenix unit cells and is integrated with a 10-dielectric zone HMFL in the diameter segment opposite the antenna source. A horn antenna feed is used for excitation in normal and oblique incidences of

ϕ
i

=
−

15
∘

and

ϕ
i

=
−

30
∘

. The designed lens prototype was fabricated with 3D-printing technology and printed metasurfaces for several particular cases of focal displacement. The measurements of the proposed HMFL beamformer are presented, demonstrating a close correlation between simulated and experimental results.
High thermoelectric performances of monolayer GeTe allotropes
Authors: Gong L J , Han Q Z , Yang J , Shi H L , Ren Y H , Zhao Y H , Yang H , Liu Q H , Jiang Z T
Published: October 2024

Aiming at finding wide-temperature-zone thermoelectric (TE) materials, five kinds of monolayer GeTe allotropes including the newly designed γ-, δ-, and ɛ-GeTe monolayers and the usual α- and β-GeTe ones are constructed. By using the density functional theory and the nonequilibrium Green’s function method, all their electronic properties and TE transport properties are comparatively investigated. It is found that the room-temperature figure of merit ZT of the γ-GeTe (ɛ-GeTe) along the armchair (zigzag) direction can amount to 4.5 (3.5), which is further increased to 7.15 (5.91) at 700 K. These ZT values are much higher than the other IV–VI compounds usually with ZT < 3, indicating that the armchair γ-GeTe and the zigzag ɛ-GeTe we designed here can be used as superior wide-temperature-zone and high-performance TE materials in the temperature range from 300 K to 700 K. Moreover, with the increase of temperature, the ZT peaks will become wider in width and move towards the position of zero chemical potential, which will make the GeTe-based TE devices work at low bias voltages more efficiently. This work should be an important reference on the way to the stage of

Z
T
⩾
4

, which will motivate more explorations into the high-performance TE materials working in a wider temperature scope.
Synergistic effect of molybdenum dioxide wrapped nitrogen doped carbon nanotubes in binder-free anodes for enhanced lithium storage properties
Authors: Zhang Hui , Tan Zhi , Xia Yuwei , Wang Chao , Pang Haili , Bai Xiaoxia , Liu Hao , Khosla Ajit
Published: October 2024

Molybdenum dioxide (MoO2) is regarded as a potential anode for lithium-ion batteries due to its highly theoretical specific capacity. However, its further application in lithium-ion battery is largely limited by insufficient practical discharge capacity and cyclic performance. Here, MoO2 nanoparticles are in-situ grown on three-dimensional nitrogen doped carbon nanotubes (NCNTs) on nickel foam substrate homogeneously using a simple electro-deposition method. The unique structural features are favorable for lithium ions insertion and extraction and charge transfer dynamics at electrode/electrolyte interface. As a proof of concept, the as-synthesized nanocomposites have been employed as anode for lithium-ion battery, exhibiting a reversible and significantly improved discharge capacity of ∼517 mA h g−1 at the current density of 150 mA g−1 as well as superior cycle and rate performance. The first-principle calculations based on density functional theory and electrochemical impedance spectroscopy results demonstrate a reduced energy barrier of lithium ions diffusion, improved lithium storage behavior, reduced structure collapse, and significantly enhanced charge transfer kinetics in MoO2/NCNTs nanocomposites with respect to MoO2 powder. The excellent performance makes as-prepared MoO2/NCNTs nanocomposites promising binder-free anode for high performance lithium-ion batteries. This work also provides important theoretical insights for other state-of-the-art batteries design.
The role of volume averaging effects, beam hardening, and phantom scatter in dosimetry of grid therapy
Authors: Khan Ahtesham Ullah , Sengupta Bishwambhar , Das Indra J
Published: October 2024

Objective. Current reference dosimetry methods for spatially fractionated radiation therapy (SFRT) assume a negligible beam quality change, perturbation, or volume-averaging correction factor. Therefore, the aim of this work was to investigate the impact of the grid collimators on the dosimetric characteristics of a 6 MV photon beam. A detector-specific correction factor,

k

Q

grid

,
 
 

Q

msr

 

f

grid

,

f

msr

, was proposed. Several dosimeters were evaluated for their ability to measure both reference dose and grid output factors (GOFs). Approach. A Monte Carlo model of a grid collimator was created to study the change in the depth dose characteristics with the grid collimator. The impact of the collimator on the percent depth dose (PDD), electron contamination, and average photon energy was investigated. The

k

Q

grid

,
 
 

Q

msr

 

f

grid

,

f

msr

correction factors were calculated for two reference-class micro ion chambers. The reference dose and GOFs were measured with a grid collimator using six ion chambers, two silicon diodes, and a diamond detector. Main results. The PDD in the presence of the grid was observed to be steeper compared to the open field. The average photon energy increased from 1.33 MeV to 1.74 MeV with the presence of the grid collimator. The dose contribution by scattered photons was significantly higher at deeper regions for the open field compared to the grid field. The

k

Q

grid

,
 
 

Q

msr

 

f

grid

,

f

msr

correction was calculated to be <0.5%. The reference dose for all detectors, except for the CC13 and CC04 chambers, was within 1% of each other. The CC13 under-responded up to 3.2% due to volume-averaging effects. The GOFs calculated for all detectors, except Razor and A16, were within 1% of each other. Significance. The phantom scatter dictates the change in the PDD with the presence of the grid. The micro ion chambers exhibit negligible

k

Q

grid

,
 
 

Q

msr

 

f

grid

,

f

msr

correction. All detectors, except the CC13 ion chamber, were found to be suitable for SFRT reference dosimetry.
Identification of mild cognitive impairment using multimodal 3D imaging data and graph convolutional networks
Authors: Liang Shengbin , Chen Tingting , Ma Jinfeng , Ren Shuanglong , Lu Xixi , Du Wencai
Published: October 2024

Objective. Mild cognitive impairment (MCI) is a precursor stage of dementia characterized by mild cognitive decline in one or more cognitive domains, without meeting the criteria for dementia. MCI is considered a prodromal form of Alzheimer’s disease (AD). Early identification of MCI is crucial for both intervention and prevention of AD. To accurately identify MCI, a novel multimodal 3D imaging data integration graph convolutional network (GCN) model is designed in this paper. Approach. The proposed model utilizes 3D-VGGNet to extract three-dimensional features from multimodal imaging data (such as structural magnetic resonance imaging and fluorodeoxyglucose positron emission tomography), which are then fused into feature vectors as the node features of a population graph. Non-imaging features of participants are combined with the multimodal imaging data to construct a population sparse graph. Additionally, in order to optimize the connectivity of the graph, we employed the pairwise attribute estimation （PAE） method to compute the edge weights based on non-imaging data, thereby enhancing the effectiveness of the graph structure. Subsequently, a population-based GCN integrates the structural and functional features of different modal images into the features of each participant for MCI classification. Main results. Experiments on the AD Neuroimaging Initiative demonstrated accuracies of 98.57%, 96.03%, and 96.83% for the normal controls (NC)-early MCI (EMCI), NC-late MCI (LMCI), and EMCI-LMCI classification tasks, respectively. The AUC, specificity, sensitivity, and F1-score are also superior to state-of-the-art models, demonstrating the effectiveness of the proposed model. Furthermore, the proposed model is applied to the ABIDE dataset for autism diagnosis, achieving an accuracy of 91.43% and outperforming the state-of-the-art models, indicating excellent generalization capabilities of the proposed model. Significance. This study demonstrates the proposed model’s ability to integrate multimodal imaging data and its excellent ability to recognize MCI. This will help achieve early warning for AD and intelligent diagnosis of other brain neurodegenerative diseases.
Numerical study on wave attenuation via 1D fully kinetic electromagnetic particle-in-cell simulations
Authors: Yan Yize , Du Fei , Tang Jingfeng , Yu Daren , Zhao Yinjian
Published: October 2024

Electromagnetic wave-plasma interaction has drawn much attention recently due to numerous important technologies and applications, taking advantage of phenomena such as electromagnetic waves being reflected or absorbed in a plasma medium. The physics of wave-plasma interaction can be complicated, when non-uniform, non-equilibrium, or anisotropic plasmas are involved, in which numerical simulations can be used to fill the gaps between theoretical solutions and experimental measurements. Among many numerical methods, the particle-in-cell method, which can solve accurately both the electromagnetic fields and particle trajectories self-consistently, would be the best choice to study wave-plasma interaction problems as long as the computational cost can be accepted. However, the applications of particle-in-cell (PIC) on wave-plasma interaction remain rare, and the numerical effects of the PIC method on accurately evaluating the wave attenuation have not been studied in depth. In this paper, a number of numerical parameters and physical parameters are tested using a 1D electromagnetic PIC method plus Monte Carlo collision model. It is found that as long the as the basic PIC criterion is met, the PIC results can be trustable, and the numerical noise due to limited number of particles has a minor effect. The physical parameters of the EM wave frequency, amplitude, the plasma temperature, thickness, and collision type are studied, and their effects on the wave attenuation are presented. In addition, strategies on establishing simulation setup and evaluating the wave attenuation in terms of power or energy are discussed.
Additive manufactured 3D re-entrant auxetic structures for enhanced impact resistance
Authors: Nam Ryan , Nam Daniel , Naguib Hani E
Published: October 2024

This study presents a novel exploration of the geometric parameters within a 3D re-entrant auxetic lattice structure, specifically focusing on their unique impact energy absorption properties, which were systematically evaluated through drop weight impactor testing. Each lattice configuration was additively manufactured using stereolithography, allowing for precise control over strut thickness (t), re-entrant angle (θ), and the aspect ratio (h/l) of unit cells during both low and high energy impact scenarios. This study found that the overall auxetic behavior is predominantly controlled by the aspect ratio of the cell ribs, while the modulus is governed by rib thickness. A finite element model was subsequently developed to simulate the experimental impact loading conditions and was used to examine a wider range of parameters that were not experimentally tested. The simulated dynamic test results displayed the deformation trends and changes to the Poisson’s ratio. Among the studied parameters, experimental results highlighted that a lattice structure with t = 1.6 mm, θ = 65°, and a h/l ratio = 1.8 exhibited the highest specific energy absorption (SEA) under uniaxial impact deformation with 5 Joules of impact energy. Conversely, when employing 20 Joules of impact energy revealed the greatest SEA at t = 1.0 mm, θ = 65°, and an h/l ratio of 2.2. The results demonstrate unique deformation mechanism of auxetic structures under impact loading and the capacity to adapt the 3D re-entrant lattice structure for applications requiring tailored impact energy absorption.
A quantum group signature scheme with reusable keys based on four-particle Cluster states
Authors: Tian Fuyao , Lu Dianjun , Wang Chengxiang , Renqian Suonan
Published: October 2024

With the continuous development of quantum technology, researchers are constantly improving the research on quantum signatures. In the public-key cryptosystem, a quantum group signature scheme based on four-particle Cluster states is proposed. In this scheme, the four-particle Cluster states are used as quantum channels. The signer randomly generates his private key according to the public key generated by the group manager, and uses the private key to sign. The verifier uses the public key to verify the signature. The features of the scheme are as follows: the public key and private key can be reused, thus reducing the number of keys that need to be saved by the communication parties; The length of the message to be signed does not need to be the same as the length of the public and private keys, which increases the flexibility of the signature; The random sequence is used in the signature process to ensure the unpredictability of the key, thus improving the security of the scheme; The scheme has unforgeability and non-repudiation.
Bosonization and correlators of the one-dimensional Hubbard model
Authors: Ovchinnikov A A
Published: October 2024

We present a simple derivation of the Luttinger liquid relation for the one-dimensional Hubbard model, considering a finite U and in the

U
=
∞

limit. We describe a simple solution of the Hubbard model in the infinite repulsion limit and use it to calculate the correlators of the model in this limit in a simple and physical way using the bosonization technique. We then calculate the asymptotics of the correlators of the model at arbitrary U through a single parameter, which can be calculated from the Bethe Ansatz solution. Our derivation of the critical exponents is simple and allows one to express different physical operators of the Hubbard model through the charge and spin Bose fields in a direct and physically transparent way.
Closed-form solutions for Bernoulli and compound Poisson branching processes in random environments*
Authors: Kutsenko Anton A
Published: October 2024

For branching processes, the generating functions for the limit distributions of the so-called ratios of probabilities of rare events satisfy Schröder-type integral–functional equations. With the exception of a few special cases, the corresponding equations cannot be solved analytically. I found a large class of Poisson-type offspring distributions for which the Schröder-type functional equations can be solved analytically. Moreover, for the asymptotics of limit distributions, the power and constant factors can be written explicitly. As a bonus, Bernoulli branching processes in random environments are treated. The beauty of this example is that the explicit formula for the generating function is unknown. Nevertheless, the closed-form expressions for the power and constant factors in the asymptotic can be written with the help of some effective techniques. The asymptotic expansion also contains oscillatory terms absent in the Poisson case. It is shown that at power three in the Bernoulli binomial kernels, short-phase discrete oscillations turn into long-phase continuous ones.