bluuebunny/crossref_metadata_2025 huggingface dataset:
Perspective on imaging antiferromagnetic domains in thin films with the magneto-optical birefringence effect
Authors: Zhou Chao , Xu Jia , Wu Tong , Wu Yizheng
Published: August 2023

Antiferromagnets are considered to be a promising host material for the next generation of magnetic storage due to their high stability and stray-field-free property. However, the absence of net magnetization in antiferromagnets renders conventional magnetometry ineffective, posing a great challenge in investigating microscopic antiferromagnetic (AFM) properties under magnetic or electric fields. In this Perspective, we provide an overview of various AFM domain imaging techniques and discuss the most promising optical imaging method based on the magneto-optical birefringence (MOB) effect. Additionally, we highlight recent advances in imaging AFM domains utilizing the MOB technique. This Perspective aims to provide a comprehensive review of the current research and potential future directions based on the MOB imaging technique, which could pave the way for the development of more efficient and reliable magnetic storage devices based on antiferromagnets.
Numerical investigation on expansion–deflection nozzle flow during an ascending–descending trajectory
Authors: Wang Ge , Zhou Bocheng , Guan Ben , Yang Haiwei
Published: August 2023

The flow characteristics of an annular expansion–deflection (ED) nozzle are investigated numerically during an ascending–descending trajectory over a large nozzle pressure ratio span. The shock pattern evolution, nozzle operation mode transition, nozzle flow hysteresis, and thrust variation during this trajectory are examined, and the interactions between them are discussed. A new criterion for distinguishing the open and closed wake modes of the ED nozzle is proposed based on a perturbation front in combination with sonic lines. Using this criterion, an exact boundary between the open and closed wake modes can be readily drawn. The present study shows that the interaction between the shock pattern transition and nozzle operation mode transition is indirect. During the ascent, the open-to-closed wake mode transition lays the foundation of the downstream shock pattern variation. During the descent, however, the stretching of the dominating Mach stem delays the nozzle closed-to-open wake mode transition. The different flow mechanisms during the ascent and descent result in an overall hysteresis of nozzle operation mode transition. The nozzle thrust undergoes dropping-rising developments (the thrust troughs) in the ascent and descent. These thrust troughs are also found to be the results of two very different flow mechanisms, namely, the forward–backward movement of shock separation point on nozzle shroud and the pressure rise on pintle base after closed-to-open mode transition.
A robust phase-locking strategy for optimal applications of various optical feedback cavity-enhanced spectroscopies in harsh environments
Authors: Ge Hu , Hu Jin , Wang Rui , zhao Gang , Ma Weiguang , Chen Weigen , Wan Fu
Published: August 2023

In various optical feedback cavity-enhanced spectroscopies (OF-CESs) based on absorption or scattering, conventional phase-locking methods are constrained by their ability to handle only minor phase deviations. This limitation is due to the source of an error signal for phase adjustment. This paper introduces a robust approach for phase-locking, which combines the shape and intensity of cavity transmission profiles to identify phase deviations. The advantage of this combination is that it can always generate a suitable error signal, irrespective of the phase's position in the entire 2π period. The outstanding performance of the corresponding servo loop under severe airflow shocks demonstrates that our approach significantly increases the feasibility of applying various OF-CES setups for real-time, in situ gas detection in harsh environments.
Smoothed particle hydrodynamics with κ-ε closure for simulating wall-bounded turbulent flows at medium and high Reynolds numbers
Authors: Bao Tingting , Hu Jun , Huang Can , Yu Yong
Published: August 2023

In this study, an improved SPH (smoothed particle hydrodynamics) method coupling the κ-ε turbulence model and the wall function is proposed to simulate wall-bounded turbulent flows at medium and high Reynolds numbers. The second-order partial derivative term of the composite function containing the turbulent viscosity coefficient is decomposed into the sum of two terms, which helps SPH to avoid numerical errors and difficulties in dealing with boundary conditions in the nested approximation of first-order partial derivatives. Particle shifting technique, δ-SPH method, and graphics processing unit parallel technology are used in the simulations to ensure uniform particles, smooth pressure field, and high computational efficiency, respectively. The SPH method with the κ-ε turbulence model and the wall function is tested and validated by simulating four classical wall-bounded turbulent flows at medium and high Reynolds numbers, which are the turbulent flat plate boundary layer at Re = 4.2 × 106 and Re = 107, backward step separation flow at ReH = 3025, the flow around the airfoil at Re = 3 × 106, and the flow around the pitching airfoil at Re = 1.35 × 105, respectively. The simulation results are consistent with the references, validating the suitability of the current SPH method for simulating wall-bounded turbulent flows at medium and high Reynolds numbers. Finally, the airfoil motion combining the pitching and deforming at Re = 3 × 106 is investigated by the current SPH method. The results show that the deformation of the airfoil's relative thickness affects the lift coefficients of the pitching airfoil. Furthermore, the increase in the relative thickness increment reduces the amplitude of the lift coefficient, while the increase in the deformation period has little effect on the amplitude of the lift coefficient.
Active dual-control terahertz electromagnetically induced transparency analog in VO2 metasurface
Authors: Wang Hong , Zhang Yuting , Hu Fangrong , Jiang Mingzhu , Zhang Longhui , Zhang Wentao , Han Jiaguang
Published: August 2023

In this paper, an active dual-control electromagnetically induced transparency (EIT) analog is realized by using vanadium dioxide (VO2) metasurface on a sapphire substrate. The unit cell of the metasurface is a composite-split-ring-resonator (CSRR) composed of two resonators, one of which containing gold pattern and VO2 is named as VSRR and the other containing two T-type resonators is called TTR. The resonant frequency of VSRR and that of TTR are located at 0.43 and 0.75 THz, respectively. While, the CSRR have two resonant frequencies at 0.39 and 0.72 THz, and an EIT-like band has a central frequency at 0.56 THz. When the metasurface is electrically stimulated, the insulator-to-metal-transition (IMT) of VO2 can result in the reconstruction of the metasurface. Therefore, the EIT resonance can be controlled by bias voltages. At central frequency of 0.56 THz, a modulation depth of 87.7% and a group delay of 2.7 ps are obtained. The EIT mechanism is further explained by using a coupled Lorentz model, and theoretical calculation and simulation show good agreement with the experiment. Moreover, by mechanically adjusting the incidence angle, the adjustable EIT-like phenomenon is also observed and the modulation depth achieves 73%. This work paves a way for the development of THz modulators, switches, and slow light devices.
Highly efficient and stable near-infrared photo sensor based on multilayer MoS2/p-Si integrated with plasmonic gold nanoparticles
Authors: Abdullah Ripain A. H. , Zulkifli N. A. A. , Tan C. L. , Abd Majid W. H. , Zakaria R.
Published: August 2023

The exceptional characteristics of two-dimensional materials make them highly efficient and stable for electronic and optoelectronic applications. These materials exhibit a range of beneficial properties, such as ultrafast carrier dynamics, layer-dependent energy bandgap, tunable optical properties, low power dissipation, high mobility, transparency, flexibility, simple fabrication, and ability to confine electromagnetic energy within extremely small volumes. In this work, infrared light (980 nm) photo sensors are fabricated based on a MoS2/p-Si substrate utilizing the plasmonic phenomenon of gold nanoparticles (AuNPs) to enrich the optoelectronic properties and to enhance the photoresponse. The infrared light response for (Au NPs MoS2) comes from the strong interlayer coupling, which narrow the energy gap in the heterojunction area, thus rendering heterostructures to longer wavelength detection ability. Considering the low light absorption due to indirect bandgap essence of multilayer MoS2, its infrared responsivity further enhanced by 100.21% with a response rate of 42.39/95.44 μs (1 kHz) at a bias of 3 V, a repeatability responsivity of up to 0.59 A/W, and a detectivity of 4.5 × 1010 Jones with a maximum of 9.57 mW/cm2 light intensity, which is maintained through surface plasmon resonance (SPR). The plasmon-assisted photo sensors can be seamlessly integrated into the semiconductor industry to boost the optoelectronic performance in practical applications.
Stability and Bautin bifurcation of four-wheel-steering vehicle system with driver steering control
Authors: Miao Pengcheng , Li Denghui , Yue Yuan , Grebogi Celso
Published: August 2023

In this paper, the stability and Bautin bifurcation of a four-wheel-steering (4WS) vehicle system, by considering driver steering control, are investigated. By using the central manifold theory and projection method, the first and second Lyapunov coefficients are calculated to predict the type of Hopf bifurcation of the vehicle system. The topological structure of Bautin bifurcation, a degenerate Hopf bifurcation of the 4WS vehicle system, is presented in parameter space, and it reveals the dynamics of the vehicle system of different choices of control parameters. The influences of system parameters on critical values of the bifurcation parameter are also analyzed. It is shown that with the increase in the frontal visibility distance of the driver control strategy coefficient and the cornering stiffness coefficients of rear wheels, the critical speed increases. Nevertheless, the critical speed decreases with the increase in the distance from the center of gravity of the vehicle to the front axles, Driver’s perceptual time delay, and cornering stiffness coefficients of the front wheels.
Gate-modulated reflectance spectroscopy for detecting excitonic states in two-dimensional semiconductors
Authors: Xue Mengsong , Watanabe Kenji , Taniguchi Takashi , Kitaura Ryo
Published: August 2023

We have developed a microspectroscopy technique for measuring gate-modulated reflectance to probe excitonic states in two-dimensional transition metal dichalcogenides. Through the use of gate-modulated spectroscopy, we were able to detect excited states of excitons and trions, which would typically have weak optical signals in traditional reflectance spectroscopy. Using a transfer matrix method for spectral analysis, the binding energy of trion 2s was determined to be 26 meV. As observing the Rydberg series of excitonic states provides fruitful information on the strong Coulomb interaction in two-dimensional systems, gate-modulated spectroscopy can be a versatile tool for understanding underlying many-body physics as well as designing next-generation quantum optoelectronics based on two-dimensional materials.
Comment on “Transverse vibration analysis of single-layered graphene sheet under magneto-thermal environment based on non-local plate theory [J. Appl. Phys. 116(16), 164303 (2014)]” and “Nonlocal elasticity based magnetic field affected vibration response of double single-walled carbon nanotube systems [J. Appl. Phys. 111(11), 113511 (2012)]”
Authors: Sinha Rakesh , Mishra Ankit
Published: August 2023

The impact of a time-varying external magnetic field on carbon nanotubes has been studied using Maxwell’s equations in the mentioned articles. However, the Maxwell’s equations are erroneously presented in the papers. The incorrect Maxwell’s equations, their derivatives, and the Lorentz force equations have all been examined in this work. In this article, we have endeavored to ensure that the equations are formatted correctly and have made an effort to do so. We have made an effort to intuitively correct the equations’ errors. We did not comment on the other portions of the mentioned articles; instead, we restricted ourselves to the examination of the impact of Maxwell’s equations and Lorentz force equations.
Perspectives on MXene-PZT based ferroelectric memristor in computation in memory applications
Authors: Zhang Miaocheng , Wei Yixin , Liu Cheng , Ding Zixuan , Liang Xin , Ming Sen , Wang Yu , Shao Weijing , Hu Ertao , Wang Xinpeng , Zhang Yerong , Zhang Minggao , Xu Jianguang , Tong Yi
Published: August 2023

Lead zirconate titanate (PZT) is the promising candidate in advanced ferroelectric memory application due to its excellent piezoelectricity, ferroelectricity, pyroelectricity, non-linear dielectric behavior, multiferroic properties, high ferroelectric Curie temperature, and extremely strong stability. It has gained attention in the field beyond von-Neumann computing, which inspires the development of computation in memory applications. Various structures of the ferroelectric memristive device, including ferroelectric field effect transistor, tunnel junctions, nonvolatile memory, and capacitor, based on PZT have been proposed for the realization of computation in memory application. On the other hand, unique designs realize the performance enhancement of PZT ferroelectric memristive devices, i.e., the insertion of 2D material MXene. This perspective further points out some of the challenges that MXene-PZT based ferroelectric memristive devices encounter in reality and finally give our viewpoint on possible developments toward computation in memory in a neuromorphic platform.
In situ monitor of superhydrophobic surface degradation to predict its drag reduction in turbulent flow
Authors: Zhang Linsheng , Crick Colin R. , Poole Robert J.
Published: August 2023

In situ monitoring is the most insightful technique to examine superhydrophobic surface degradation as it provides real-time information on the liquid–solid interface in a continuous, noninvasive manner. Using reflecting-pixel intensity, we introduced a simple method to characterize in situ the air-plastron over a superhydrophobic surface in a turbulent channel flow. Prior to the turbulent experiments, a no-flow hydrostatic test was carried out to determine a critical absolute pressure under which the surfaces are able to maintain the air layer for a prolonged period of time. Pressure-drop and velocity measurements were conducted in a series of turbulent flow tests. Resulting from the coupling effects of normal and shear stresses over the plastron, the air layer was progressively lost with flow time which caused the drag ratio (i.e., the friction factor ratio between superhydrophobic and smooth surfaces) to increase. Meanwhile, the average pixel intensity also increased with time and exhibited a consistent trend with the drag ratio evolution. At a fixed near-wall y/h location (within the viscous sublayer), the velocity increased with time since the shear stress increased. However, a velocity measurement at the center of the channel exhibited a decrease, consummate with an overall downward shift of the velocity profile. Both pressure-drop and velocity results were observed to be correlated with the average pixel intensities of the images captured over the surfaces, and therefore, this is a suitable proxy measure of the plastron. This technique is confirmed to be valid for monitoring the air layer and, hence, predicting the consequent loss of drag reduction.
Analysis of knock onset based on two-dimensional direct numerical simulation and theory of explosive transition of deflagration
Authors: Morii Youhi , Tsunoda Akira , Dubey Ajit Kumar , Maruta Kaoru
Published: August 2023

In this study, we analyzed data from a two-dimensional (2D) direct numerical simulation (DNS) that reproduced the knocking experiment in order to elucidate the knocking phenomenon. First, it was confirmed that the reaction front behavior in 2D DNS could be reproduced as a one-dimensional (1D) laminar premixed flame simulation at extreme conditions. Furthermore, a detailed study using a 1D laminar premixed flame revealed a strong relation between the timing of knock onset and the flame propagation limit of the 1D laminar premixed flame at elevated temperature and pressure conditions. To clarify this relation, we introduced the theory of “explosive transition of deflagration.” This theory shows that when the Lewis number is unity, the time evolution of the normalized fuel mass fraction and temperature in a 0D homogeneous ignition is equal to the temporal evolution observed in a 1D laminar premixed flame, if the spatiotemporal transformation is properly applied. Furthermore, the rate at which the normalized fuel mass fraction decreases in the preheat zone was found to depend on the Lewis number, and when the Lewis number is greater than unity, no flame structure exists above a certain threshold temperature. Finally, the mechanism of knock onset was explained by considering the theory of explosive transition of deflagration and explosive transition boundary plotted on a pressure-temporal diagram.
Suppressing the pancake bouncing induced secondary contact on superhydrophobic surfaces via jet splash
Authors: Liu Lei , Guo Chunfang , Yang Rui , Lu Jiangtao , Liu Senyun
Published: August 2023

Pancake bouncing of water droplets on superhydrophobic surfaces has been extensively studied, because the reduction in solid–liquid contact time shows great potential for self-cleaning, anti-icing, etc. However, the behavior of a pancake-bouncing droplet in the ambient air and its subsequent interaction with the underlying surface remain unrevealed, which is actually crucial for practical applications. In this Letter, we comprehensively investigate the overall dynamics of droplets on post-array superhydrophobic surfaces by extending the range of impact velocities. An unreported phenomenon was observed, whereby the retracting droplet undergoes vertical elongation and re-contacts the underlying surface following the pancake bouncing event. As the impact velocity increases, the submillimeter-scale posts notably influence the droplet splash, where tiny droplets are ejected from the edges of lateral liquid jets through the posts. Experimental results and scale analysis show that the critical Weber number for this jet splash phenomenon decreases with the post spacing and the post edge length over a certain range. The violent jet splash occurring at higher Weber numbers reduces the mass of the remaining droplet and, consequently, diminishes the diameter prior to retraction, thereby suppressing the secondary contact with the surface. Our findings are believed to provide valuable insight for the understanding and the application of the pancake bouncing effect.
Wet spinning is employed to produce spider silk with high elasticity
Authors: Zhang Jie , Gong Mengxin , Meng Qing
Published: August 2023

Spider silk exhibits exceptional strength and elasticity in its natural form. Over the course of several decades, researchers have been working on artificially spinning recombinant spider silk proteins (spidroin) in order to replicate the remarkable mechanical properties of natural spider silk. In this study, we utilized the wet spinning method to investigate the relationship between the concentration of the coagulation bath and fiber performance. We discovered that the concentration of methanol plays a crucial role in determining the continuity, diameter, and mechanical properties of the fibers. Lower concentrations of methanol favor the production of continuous, thinner fibers with higher strain. Additionally, secondary stretching during the spinning process contributes to the production of silk fibers with stable mechanical properties and thermal stability. By employing different concentrations of methanol and applying additional stretching, we successfully produced silk fibers with a high strain of 2.1652 ± 0.3871 mm/mm. Furthermore, these wet-spun fibers demonstrated the ability to promote the growth of Schwann cells, indicating their potential application in the field of biomedical engineering. Hence, the exceptional mechanical properties and the ability to promote cellular growth make the obtained spider silk fibers highly promising for various biomedical applications.
On the migration of a droplet driven by thermocapillary action in a wettability-confined track
Authors: Ma Cheng , Li Chunxi , Xie Xiongfei , Ye Xuemin
Published: August 2023

We report a study of the thermocapillary migration of droplets under a radial thermal gradient and in a wettability-confined track. A three-dimensional mathematical model is established based on the lubrication approximation. By considering the contact-line dynamics, a method for determining the velocity of the contact line in different directions is proposed for a three-dimensional droplet. Numerical simulations are performed to investigate the variations in the droplet profile, contact angle, and contact line. Three substrate-wettability cases are considered: uniform, temperature-dependent, and track-dependent wettability. The results show that when the substrate wettability is uniform, the droplet height initially decreases rapidly, and its center becomes concave and then gradually evolves into a ring-like morphology. Reducing the temperature sensitivity of the liquid–gas interfacial tension or increasing the temperature sensitivity of the liquid–solid interfacial tension decreases the equilibrium contact angle and accelerates thermocapillary migration. When a droplet spreads in a wettability-confined track, a wave-like peak is formed on each side of the droplet along the track direction until it finally separates into two distinct parts. As the track width is decreased, the time taken for a droplet to split into two smaller droplets advances, and the separation time presents a linear relationship with the track width.
Fine-tuning ionic transport through hybrid soft nanochannels: The role of polyelectrolyte charge density distribution
Authors: Heydari Amirhossein , Khatibi Mahdi , Ashrafizadeh Seyed Nezameddin
Published: August 2023

This study investigates a hybrid nanochannel consisting of two cylindrical and conical parts coated with a soft layer exhibiting either of four different spatial distribution functions: constant (type I), exponential (type II), sigmoidal (type III), and soft-step (type IV). The Poisson–Nernst–Planck and Navier–Stokes equations are numerically solved using the finite element method under steady-state conditions. The research focuses on the modification of behavior and enhancement of performance in nanochannels inspired by nature. Considering the spatial variation in charge density distribution and the limited understanding of ion transport mechanisms, this study highlights the importance of modeling tools in advancing this field. The findings contribute to the development of effective strategies for controlling and manipulating the behavior of charged nanochannels. The results demonstrate that changing the decay length from 0.2 to 1 at a concentration of 1 mM leads to an increase in the rectification factor for type II up to 6.129, i.e., 5.7 times. Furthermore, varying NPEL/NA from 25 to 100 mol m−3 at Vapp=+1 V results in ionic selectivity of 0.9072, 0.2009, 0.1543, and 0.9031 for functions of type I to type IV, respectively. These findings not only enhance our understanding of ion transport mechanisms in hybrid nanochannels but also suggest that manipulating the charge density of the soft layer enables the production of intelligent nanochannels with applications in separation, diagnostics, and sensing.
Multifunctional high-density ultrasonic microsensor for ranging and 2D imaging
Authors: Ruan Tao , Wang Qi , Hu Zhiyong , Xu Qingda , Xi Ye , Li Lixuan , Yang Bin , Liu Jingquan
Published: August 2023

Ultrasound has been implemented as a powerful tool for noninvasive imaging and non-contact ranging. However, the size and single-function of traditional ultrasonic probes have limited their adaptability to complex application scenarios in the artificial intelligence era. This paper reports a multifunctional microsensor based on a piezoelectric micromachined ultrasonic transducer (pMUT) array that can be used for ranging and 2D imaging at the same time, in air, with a small working size (2 × 0.8 mm2) and low driving voltage (10 V). A back-end circuit was also designed to optimize the performance of the pMUT array, resulting in a peak-to-peak value of 158 mV. The characterization of the multifunctional microsensor demonstrated that it is capable of performing ranging and 2D imaging simultaneously with high spatial resolution (∼1 mm in ranging and ∼0.2 × 0.2 mm2 in 2D-imaging), even in complex application scenarios. This paper describes a system that integrates micro-electro-mechanical systems device, back-end circuit, imaging algorithm, and denoising algorithm, which allow the microsensor to provide multiple functions. This makes it a promising tool for a wide range of human–machine interaction applications, such as gesture recognition, robotics, and healthcare.
A robust sparse identification method for nonlinear dynamic systems affected by non-stationary noise
Authors: Hao Zhihang , Yang Chunhua , Huang Keke
Published: August 2023

In the field of science and engineering, identifying the nonlinear dynamics of systems from data is a significant yet challenging task. In practice, the collected data are often contaminated by noise, which often severely reduce the accuracy of the identification results. To address the issue of inaccurate identification induced by non-stationary noise in data, this paper proposes a method called weighted ℓ1-regularized and insensitive loss function-based sparse identification of dynamics. Specifically, the robust identification problem is formulated using a sparse identification mathematical model that takes into account the presence of non-stationary noise in a quantitative manner. Then, a novel weighted ℓ1-regularized and insensitive loss function is proposed to account for the nature of non-stationary noise. Compared to traditional loss functions like least squares and least absolute deviation, the proposed method can mitigate the adverse effects of non-stationary noise and better promote the sparsity of results, thereby enhancing the accuracy of identification. Third, to overcome the non-smooth nature of the objective function induced by the inclusion of loss and regularization terms, a smooth approximation of the non-smooth objective function is presented, and the alternating direction multiplier method is utilized to develop an efficient optimization algorithm. Finally, the robustness of the proposed method is verified by extensive experiments under different types of nonlinear dynamical systems. Compared to some state-of-the-art methods, the proposed method achieves better identification accuracy.
HP1-driven phase separation recapitulates the thermodynamics and kinetics of heterochromatin condensate formation
Authors: Tortora Maxime M. C. , Brennan Lucy D. , Karpen Gary , Jost Daniel
Published: August 2023

The spatial segregation of pericentromeric heterochromatin (PCH) into distinct, membrane-less nuclear compartments involves the binding of Heterochromatin Protein 1 (HP1) to H3K9me2/3-rich genomic regions. While HP1 exhibits liquid–liquid phase separation properties in vitro, its mechanistic impact on the structure and dynamics of PCH condensate formation in vivo remains largely unresolved. Here, using a minimal theoretical framework, we systematically investigate the mutual coupling between self-interacting HP1-like molecules and the chromatin polymer. We reveal that the specific affinity of HP1 for H3K9me2/3 loci facilitates coacervation in nucleo and promotes the formation of stable PCH condensates at HP1 levels far below the concentration required to observe phase separation in purified protein assays in vitro. These heterotypic HP1–chromatin interactions give rise to a strong dependence of the nucleoplasmic HP1 density on HP1-H3K9me2/3 stoichiometry, consistent with the thermodynamics of multicomponent phase separation. The dynamical cross talk between HP1 and the viscoelastic chromatin scaffold also leads to anomalously slow equilibration kinetics, which strongly depend on the genomic distribution of H3K9me2/3 domains and result in the coexistence of multiple long-lived, microphase-separated PCH compartments. The morphology of these complex coacervates is further found to be governed by the dynamic establishment of the underlying H3K9me2/3 landscape, which may drive their increasingly abnormal, aspherical shapes during cell development. These findings compare favorably to 4D microscopy measurements of HP1 condensate formation in live
Drosophila
embryos and suggest a general quantitative model of PCH formation based on the interplay between HP1-based phase separation and chromatin polymer mechanics.
Silver electroceutical technology to treat sarcopenia
Authors: Kim Min Young , Shin Hyun Young , Cho Sung Chun , Yang Sohae , Intisar Aseer , Woo Hyeong Jung , Choi Youn-Suk , You Chang-Lim , Kang Jong-Sun , Lee Yun-Il , Park Sang Chul , Yea Kyungmoo , Oh Tae Gyu , Downes Michael , Evans Ronald M. , Kim Minseok S.
Published: August 2023

While the world is rapidly transforming into a superaging society, pharmaceutical approaches to treat sarcopenia have hitherto not been successful due to their insufficient efficacy and failure to specifically target skeletal muscle cells (skMCs). Although electrical stimulation (ES) is emerging as an alternative intervention, its efficacy toward treating sarcopenia remains unexplored. In this study, we demonstrate a silver electroceutical technology with the potential to treat sarcopenia. First, we developed a high-throughput ES screening platform that can simultaneously stimulate 15 independent conditions, while utilizing only a small number of human-derived primary aged/young skMCs (hAskMC/hYskMC). The in vitro screening showed that specific ES conditions induced hypertrophy and rejuvenation in hAskMCs, and the optimal ES frequency in hAskMCs was different from that in hYskMCs. When applied to aged mice in vivo, specific ES conditions improved the prevalence and thickness of Type IIA fibers, along with biomechanical attributes, toward a younger skMC phenotype. This study is expected to pave the way toward an electroceutical treatment for sarcopenia with minimal side effects and help realize personalized bioelectronic medicine.
Double stress of waterlogging and drought drives forest–savanna coexistence
Authors: Mattos Caio R. C. , Hirota Marina , Oliveira Rafael S. , Flores Bernardo M. , Miguez-Macho Gonzalo , Pokhrel Yadu , Fan Ying
Published: August 2023

Forest–savanna boundaries are ecotones that support complex ecosystem functions and are sensitive to biotic/abiotic perturbations. What drives their distribution today and how it may shift in the future are open questions. Feedbacks among climate, fire, herbivory, and land use are known drivers. Here, we show that alternating seasonal drought and waterlogging stress favors the dominance of savanna-like ecosystems over forests. We track the seasonal water-table depth as an indicator of water stress when too deep and oxygen stress when too shallow and map forest/savanna occurrence within this double-stress space in the neotropics. We find that under a given annual precipitation, savannas are favored in landscape positions experiencing double stress, which is more common as the dry season strengthens (climate driver) but only found in waterlogged lowlands (terrain driver). We further show that hydrological changes at the end of the century may expose some flooded forests to savanna expansion, affecting biodiversity and soil carbon storage. Our results highlight the importance of land hydrology in understanding/predicting forest–savanna transitions in a changing world.
The liquid-to-solid transition of FUS is promoted by the condensate surface
Authors: Shen Yi , Chen Anqi , Wang Wenyun , Shen Yinan , Ruggeri Francesco Simone , Aime Stefano , Wang Zizhao , Qamar Seema , Espinosa Jorge R. , Garaizar Adiran , St George-Hyslop Peter , Collepardo-Guevara Rosana , Weitz David A. , Vigolo Daniele , Knowles Tuomas P. J.
Published: August 2023

A wide range of macromolecules can undergo phase separation, forming biomolecular condensates in living cells. These membraneless organelles are typically highly dynamic, formed reversibly, and carry out essential functions in biological systems. Crucially, however, a further liquid-to-solid transition of the condensates can lead to irreversible pathological aggregation and cellular dysfunction associated with the onset and development of neurodegenerative diseases. Despite the importance of this liquid-to-solid transition of proteins, the mechanism by which it is initiated in normally functional condensates is unknown. Here we show, by measuring the changes in structure, dynamics, and mechanics in time and space, that single-component FUS condensates do not uniformly convert to a solid gel, but rather that liquid and gel phases coexist simultaneously within the same condensate, resulting in highly inhomogeneous structures. Furthermore, our results show that this transition originates at the interface between the condensate and the dilute continuous phase, and once initiated, the gelation process propagates toward the center of the condensate. To probe such spatially inhomogeneous rheology during condensate aging, we use a combination of established micropipette aspiration experiments together with two optical techniques, spatial dynamic mapping and reflective confocal dynamic speckle microscopy. These results reveal the importance of the spatiotemporal dimension of the liquid-to-solid transition and highlight the interface of biomolecular condensates as a critical element in driving pathological protein aggregation.
Range-wide differential adaptation and genomic offset in critically endangered Asian rosewoods
Authors: Hung Tin Hang , So Thea , Thammavong Bansa , Chamchumroon Voradol , Theilade Ida , Phourin Chhang , Bouamanivong Somsanith , Hartvig Ida , Gaisberger Hannes , Jalonen Riina , Boshier David H. , MacKay John J.
Published: August 2023

In the billion-dollar global illegal wildlife trade, rosewoods have been the world’s most trafficked wild product since 2005.
Dalbergia cochinchinensis
and
Dalbergia oliveri
are the most sought-after rosewoods in the Greater Mekong Subregion. They are exposed to significant genetic risks and the lack of knowledge on their adaptability limits the effectiveness of conservation efforts. Here, we present genome assemblies and range-wide genomic scans of adaptive variation, together with predictions of genomic offset to climate change. Adaptive genomic variation was differentially associated with temperature and precipitation-related variables between the species, although their natural ranges overlap. The findings are consistent with differences in pioneering ability and in drought tolerance. We predict their genomic offsets will increase over time and with increasing carbon emission pathway but at a faster pace in
D. cochinchinensis
than in
D. oliveri
. These results and the distinct gene–environment association in the eastern coastal edge of Vietnam suggest species-specific conservation actions: germplasm representation across the range in
D. cochinchinensis
and focused on hotspots of genomic offset in
D. oliveri
. We translated our genomic models into a seed source matching application,
seedeR
, to rapidly inform restoration efforts. Our ecological genomic research uncovering contrasting selection forces acting in sympatric rosewoods is of relevance to conserving tropical trees globally and combating risks from climate change.
FAN1 removes triplet repeat extrusions via a PCNA- and RFC-dependent mechanism
Authors: Phadte Ashutosh S. , Bhatia Mayuri , Ebert Hope , Abdullah Haaris , Elrazaq Essam Abed , Komolov Konstantin E. , Pluciennik Anna
Published: August 2023

Human genome-wide association studies have identified
FAN1
and several DNA mismatch repair (MMR) genes as modifiers of Huntington’s disease age of onset. In animal models, FAN1 prevents somatic expansion of CAG triplet repeats, whereas MMR proteins promote this process. To understand the molecular basis of these opposing effects, we evaluated FAN1 nuclease function on DNA extrahelical extrusions that represent key intermediates in triplet repeat expansion. Here, we describe a strand-directed, extrusion-provoked nuclease function of FAN1 that is activated by RFC, PCNA, and ATP at physiological ionic strength. Activation of FAN1 in this manner results in DNA cleavage in the vicinity of triplet repeat extrahelical extrusions thereby leading to their removal in human cell extracts. The role of PCNA and RFC is to confer strand directionality to the FAN1 nuclease, and this reaction requires a physical interaction between PCNA and FAN1. Using cell extracts, we show that FAN1-dependent CAG extrusion removal relies on a very short patch excision-repair mechanism that competes with MutSβ-dependent MMR which is characterized by longer excision tracts. These results provide a mechanistic basis for the role of FAN1 in preventing repeat expansion and could explain the antagonistic effects of MMR and FAN1 in disease onset/progression.
A crystalline carbon nitride–based separator for high-performance lithium metal batteries
Authors: Di Shuanlong , Li Hongguan , Zhai Boyin , Zhi Xiaojuan , Niu Ping , Wang Shulan , Li Li
Published: August 2023

Lithium metal anodes with ultrahigh theoretical capacities are very attractive for assembling high-performance batteries. However, uncontrolled Li dendrite growth strongly retards their practical applications. Different from conventional separator modification strategies that are always focused on functional group tuning or mechanical barrier construction, herein, we propose a crystallinity engineering–related tactic by using the highly crystalline carbon nitride as the separator interlayer to suppress dendrite growth. Interestingly, the presence of Cl
−
intercalation and high-content pyrrolic-N from molten salt treatment along with highly crystalline structure enhanced the interactions of carbon nitride with Li
+
and homogenized lithium flux for uniform deposition, as supported by both experimental and theoretical evidences. The Li–Li cell with the modified separator therefore delivered ultrahigh stability even after 3,000 h with dendrite-free cycled electrodes. Meanwhile, the assembled Li–LiFePO
4
full-cell also presented high-capacity retention. This work opens up opportunities for design of functional separators through crystallinity engineering and broadens the use of C
3
N
4
for advanced batteries.
Feedback regulation of ubiquitination and phase separation of HECT E3 ligases
Authors: Li Jingyu , Zhu Kang , Gu Aihong , Zhang Yiqing , Huang Shijing , Hu Ronggui , Hu Weiguo , Lei Qun-Ying , Wen Wenyu
Published: August 2023

Lipid homeostasis is essential for normal cellular functions and dysregulation of lipid metabolism is highly correlated with human diseases including neurodegenerative diseases. In the ubiquitin-dependent autophagic degradation pathway, Troyer syndrome–related protein Spartin activates and recruits HECT-type E3 Itch to lipid droplets (LDs) to regulate their turnover. In this study, we find that Spartin promotes the formation of Itch condensates independent of LDs. Spartin activates Itch through its multiple PPAY-motif platform generated by self-oligomerization, which targets the WW12 domains of Itch and releases the autoinhibition of the ligase. Spartin-induced activation and subsequent autoubiquitination of Itch lead to liquid–liquid phase separation (LLPS) of the poly-, but not oligo-, ubiquitinated Itch together with Spartin and E2 both in vitro and in living cells. LLPS-mediated condensation of the reaction components further accelerates the generation of polyubiquitin chains, thus forming a positive feedback loop. Such Itch–Spartin condensates actively promote the autophagy-dependent turnover of LDs. Moreover, we show that the catalytic HECT domain of Itch is sufficient to interact and phase separate with poly-, but not oligo-ubiquitin chains. HECT domains from other HECT E3 ligases also exhibit LLPS-mediated the promotion of ligase activity. Therefore, LLPS and ubiquitination are mutually interdependent and LLPS promotes the ligase activity of the HECT family E3 ligases.
Insight into the mechanism of H
+
-coupled nucleobase transport
Authors: Weng Jun , Zhou Xiaoming , Wiriyasermkul Pattama , Ren Zhenning , Chen Kehan , Gil-Iturbe Eva , Zhou Ming , Quick Matthias
Published: August 2023

Members of the nucleobase/ascorbic acid transporter (NAT) gene family are found in all kingdoms of life. In mammals, the concentrative uptake of ascorbic acid (vitamin C) by members of the NAT family is driven by the Na
+
gradient, while the uptake of nucleobases in bacteria is powered by the H
+
gradient. Here, we report the structure and function of PurT
Cp
, a NAT family member from
Colwellia psychrerythraea
. The structure of PurT
Cp
was determined to 2.80 Å resolution by X-ray crystallography. PurT
Cp
forms a homodimer, and each protomer has 14 transmembrane segments folded into a transport domain (core domain) and a scaffold domain (gate domain). A purine base is present in the structure and defines the location of the substrate binding site. Functional studies reveal that PurT
Cp
transports purines but not pyrimidines and that purine binding and transport is dependent on the pH. Mutation of a conserved aspartate residue close to the substrate binding site reveals the critical role of this residue in H
+
-dependent transport of purines. Comparison of the PurT
Cp
structure with transporters of the same structural fold suggests that rigid-body motions of the substrate-binding domain are central for substrate translocation across the membrane.
The Sde phosphoribosyl–linked ubiquitin transferases protect the
Legionella pneumophila
vacuole from degradation by the host
Authors: Kim Seongok , Isberg Ralph R.
Published: August 2023

Legionella pneumophila
grows intracellularly within the membrane-bound
Legionella-
containing vacuole (LCV) established by proteins translocated via the bacterial type IV secretion system (T4SS). The Sde family, one such group of translocated proteins, catalyzes phosphoribosyl–ubiquitin (pR-Ub) modification of target substrates. Mutational loss of the entire Sde family results in small defects in intracellular growth, making it difficult to identify a clear role for this posttranslational modification in supporting the intracellular lifestyle. Therefore, mutations that aggravate the loss of
sde
genes and caused intracellular growth defects were identified, providing a mechanistic connection between Sde function and vacuole biogenesis. These double mutants drove the formation of LCVs that showed vacuole disintegration within 2 h of bacterial contact. Sde proteins appeared critical for blocking access of membrane-disruptive early endosomal membrane material to the vacuole, as RNAi depletion of endosomal pathway components partially restored LCV integrity. The role of Sde proteins in preventing host degradation of the LCV was limited to the earliest stages of infection. The time that Sde proteins could prevent vacuole disruption, however, was extended by deletion of
sidJ
, which encodes a translocated protein that inactivates Sde protein active sites. These results indicate that Sde proteins act as temporally regulated vacuole guards during the establishment of the replication niche, possibly by constructing a physical barrier that blocks access of disruptive host compartments during the earliest steps of LCV biogenesis.
Enumerating soil biodiversity
Authors: Anthony Mark A. , Bender S. Franz , van der Heijden Marcel G. A.
Published: August 2023

Soil is an immense habitat for diverse organisms across the tree of life, but just how many organisms live in soil is surprisingly unknown. Previous efforts to enumerate soil biodiversity consider only certain types of organisms (e.g., animals) or report values for diverse groups without partitioning species that live in soil versus other habitats. Here, we reviewed the biodiversity literature to show that soil is likely home to 59 ± 15% of the species on Earth. We therefore estimate an approximately two times greater soil biodiversity than previous estimates, and we include representatives from the simplest (microbial) to most complex (mammals) organisms. Enchytraeidae have the greatest percentage of species in soil (98.6%), followed by fungi (90%), Plantae (85.5%), and Isoptera (84.2%). Our results demonstrate that soil is the most biodiverse singular habitat. By using this estimate of soil biodiversity, we can more accurately and quantitatively advocate for soil organismal conservation and restoration as a central goal of the Anthropocene.
CD47 promotes peripheral T cell survival by preventing dendritic cell–mediated T cell necroptosis
Authors: Komori Satomi , Saito Yasuyuki , Nishimura Taichi , Respatika Datu , Endoh Hiromi , Yoshida Hiroki , Sugihara Risa , Iida-Norita Rie , Afroj Tania , Takai Tomoko , Oduori Okechi S. , Nitta Eriko , Kotani Takenori , Murata Yoji , Kaneko Yoriaki , Nitta Ryo , Ohnishi Hiroshi , Matozaki Takashi
Published: August 2023

Conventional dendritic cells (cDCs) are required for peripheral T cell homeostasis in lymphoid organs, but the molecular mechanism underlying this requirement has remained unclear. We here show that T cell–specific CD47-deficient (
Cd47
 ΔT
) mice have a markedly reduced number of T cells in peripheral tissues. Direct interaction of CD47-deficient T cells with cDCs resulted in activation of the latter cells, which in turn induced necroptosis of the former cells. The deficiency and cell death of T cells in
Cd47
  ΔT
mice required expression of its receptor signal regulatory protein α on cDCs. The development of CD4
+
T helper cell–dependent contact hypersensitivity and inhibition of tumor growth by cytotoxic CD8
+
T cells were both markedly impaired in
Cd47
 ΔT
mice. CD47 on T cells thus likely prevents their necroptotic cell death initiated by cDCs and thereby promotes T cell survival and function.
Targeting STING oligomerization with small-molecule inhibitors
Authors: Humphries Fiachra , Shmuel-Galia Liraz , Jiang Zhaozhao , Zhou Jeffrey Y. , Barasa Leonard , Mondal Santanu , Wilson Ruth , Sultana Nadia , Shaffer Scott A. , Ng Sze-Ling , Pesiridis G. Scott , Thompson Paul R. , Fitzgerald Katherine A.
Published: August 2023

Stimulator of interferon genes (STING) is an essential adaptor protein required for the inflammatory response to cytosolic DNA. dsDNA activates cGAS to generate cGAMP, which binds and activates STING triggering a conformational change, oligomerization, and the IRF3- and NFκB-dependent transcription of type I Interferons (IFNs) and inflammatory cytokines, as well as the activation of autophagy. Aberrant activation of STING is now linked to a growing number of both rare as well as common chronic inflammatory diseases. Here, we identify and characterize a potent small-molecule inhibitor of STING. This compound, BB-Cl-amidine inhibits STING signaling and production of type I IFNs, IFN-stimulated genes (ISGs) and NFκB-dependent cytokines, but not other pattern recognition receptors. In vivo, BB-Cl-amidine alleviated pathology resulting from accrual of cytosolic DNA in Trex-1 mutant mice. Mechanistically BB-Cl-amidine inhibited STING oligomerization through modification of Cys
148
. Collectively, our work uncovers an approach to inhibit STING activation and highlights the potential of this strategy for the treatment of STING-driven inflammatory diseases.