Browse Articles

The deubiquitylating enzyme Fat facets promotes Fat signalling and restricts tissue growth

Abstract Tissue growth is regulated by many signals, including polarity cues. The Hippo signalling pathway restricts tissue growth and receives inputs from the planar cell polarity-controlling Fat signalling pathway. The atypical cadherin Fat restricts growth via several mechanisms that ultimately control the activity of the pro-growth transcriptional co-activator Yorkie. Fat signalling activates the Yorkie inhibitory kinase Warts, and modulates the function of the FERM protein Expanded, which promotes Hippo signalling and also directly inhibits Yorkie. Although several Fat pathway activity modulators are known to be involved in ubiquitylation, the role of this post-translational modification in the pathway remains unclear. Moreover, no deubiquitylating enzymes have been described in this pathway. Here, using in vivo RNAi screening, we identify the deubiquitylating enzyme Fat facets as a positive regulator of Fat signalling with roles in tissue growth control. Fat facets interacts genetically and physically with Fat signalling components and regulates Yorkie target gene expression. Thus, we uncover a role for reversible ubiquitylation in the control of Fat signalling and tissue growth regulation.

Nonlinear response of hybrid magnons in synthetic antiferromagnets

In this study, we investigated the nonlinear response of hybrid magnons consisting of acoustic and optic magnon modes in in-plane magnetized synthetic antiferromagnets. Using the heterodyne magneto-optical Kerr effect technique, we optically measured the properties of hybrid magnons under various excitation powers. These measurements revealed that the increase in the excitation power changed the resonance spectrum and the intensity distribution of the magnon dispersion relation due to the nonlinear dynamics of propagating magnons. This study advances the understanding of the nonlinear behavior of hybrid magnons, contributing to the future development of magnonic logic circuits and quantum devices.

Identification of quantitative trait nucleotides for grain quality in bread wheat under heat stress

Enhanced AlGaN/GaN ultraviolet phototransistor: Achieving single-pixel imaging and communication

The ideal combination of high sensitivity and fast response speed is crucial for advanced photodetectors. Herein, we present a normally-off, visible-blind ultraviolet (UV) AlGaN/GaN phototransistor featuring a fluorine-ion-implanted trench gate structure. This design effectively disrupts the conductive channel of the AlGaN/GaN heterostructure, drastically reducing the dark current to the magnitude of 0.1 pA. The trench structure enhances the localized electric field in the confined gate region, significantly improving UV detection sensitivity. Additionally, the finite electric field enhancement induced from fluorine ions (F− ions) accelerates the establishment of photogenerated electron channels. Consequently, the phototransistor exhibits ultrafast response speed, with rise and decay times of 1.5 and 6.7 μs, respectively, along with an exceptional specific detectivity of 3.45 × 1016 cm·Hz1/2 W−1. The detection of weak UV light reaches as low as 76.0 nW/cm2. This remarkable detection capability allows the device to perform high-fidelity single-pixel imaging and facilitates real-time UV communication. The proposed AlGaN/GaN phototransistor, characterized by a straightforward fabrication process and excellent photoresponse performance, presents enticing prospects for multiple performance compatible optoelectronic devices.

Study on negative friction of pile foundation in homogeneous layered soil in collapsible loess area

High temperature complementary heterojunction tunnel field-effect transistors for low-power circuits

Tunnel field-effect transistor (TFET) is emerging as a promising alternative to overcome the thermionic limit of 60 mV/dec in subthreshold swing (SS) inherent to metal-oxide-semiconductor field-effect transistor through the band-to-band tunneling (BTBT) mechanism. TFET offers significant potential for applications in future industries, such as low-power sensors and wearable devices, where extreme energy efficiency is critical. Notably, due to the characteristic of the BTBT mechanism, TFET can maintain stable SS performance even at high temperature, enabling low-power operation under such condition. Although numerous theoretical predictions and simulations support this capability, experimental validation has not yet been demonstrated. As electric and autonomous vehicles advance, the demand for automotive semiconductors has increased, highlighting the importance of transistor technology that remains stable at high temperatures and consumes less power. Here, we report high temperature TFETs showing SS < 60 mV/dec through vertical heterojunction of two-dimensional semiconductors. n-TFET and p-TFET were implemented via BP-MoS2 and WSe2-ReS2 heterojunction, respectively. Both TFETs reached SSmin under 50 mV/dec at room temperature and maintained SS1dec_avg under 60 mV/dec up to 400 K. These findings pave the way for low-power circuits capable of operation in harsh environments.

How adaptive social robots influence cognitive, emotional, and self-regulated learning

Abstract As educational environments become more diverse, adaptive technologies like social robots hold promise for providing individual support to learners. This study investigated the role of adaptive teaching of a robot on students’ learning outcomes, emotions, and self-regulated learning (SRL). A total of 120 participants (aged 18–60 years, M age = 30.25, SD age = 10.06, 64.3% female) engaged in an interactive vocabulary learning task with varying guidance levels by the robot. Control conditions included fixed guidance, offering either simple guidance with no hints (condition 1) or enhanced guidance, constantly adding hints (condition 2). In the adaptive conditions, the robot adjusted the number of hints based on learners’ recent performance and enjoyment (condition 3) or additionally personalized hints to specific mistakes (condition 4). The results showed no direct or indirect effects of adaptive guidance on task performance or cognitive learning compared to fixed guidance. Instead, adaptive guidance significantly reduced on-task enjoyment compared to enhanced guidance, suggesting that unexpected variability in robot behavior may negatively affect emotional learning experience. However, personalized adaptive guidance increased certain SRL behaviors, indirectly benefiting learning outcomes. These findings highlight the need for further refinement of adaptive social robots to better meet individual learner needs and optimize outcomes.

Piezo-strain induced nonvolatile control of magnetic skyrmion nonlinear dynamics for artificial synapse device applications

High-performance artificial synaptic devices that emulate the functions of biological synapses are crucial for advancing energy-efficient brain-inspired computing systems. Current studies predominantly focus on memristive devices, which achieve synaptic functions through nonvolatile electric current-assisted carrier modulation. However, these methods often suffer from excessive energy consumption. Here, a type of low-energy-consumption artificial synapse based on strain-mediated electric-field control of magnetic skyrmion's radius is demonstrated, where the energy consumption is 10 fJ per state and the non-volatility is achieved by local ferroelectric domain switching under bipolar electric fields. The proposed skyrmion-based synaptic device can replicate essential synaptic behaviors, including long-term potentiation (LTP), long-term depression (LTD), paired-pulse facilitation, paired-pulse depression, and spiking-time-dependent plasticity, aligning it closely with the biological synaptic system. The synaptic weight change and non-linearity of the artificial synapse are emulated by modulating the magnetic skyrmion's radius through precisely engineering the applied electric-field pulses. Simulation using the Modified National Institute of Standards and Technology database reveals that the pattern recognition rate decreases exponentially with increasing LTP/LTD non-linearity, quantifying the effect of the LTP/LTD non-linearity on the pattern recognition rate. This work underscores the potential of strain-mediated electric-field control of single skyrmion's radius as a groundbreaking approach for developing high density and low-energy consumption artificial synaptic devices.

Stigma toward people living with HIV among healthcare providers in midwifery hospitals in Shenzhen, China from 2020 to 2023

On the dependence of internal stress on dislocation inclination pattern in HVPE-GaN substrates

Internal stress in gallium nitride (GaN) induced during epitaxy growth can degrade the performance of GaN devices. This work studied the internal stress distribution and dislocation configuration around an inclusion of ∼300 μm in GaN substrates grown by hydride vapor phase epitaxy, by means of combined Raman spectroscopy, x-ray topography, and two-photon excitation photoluminescence. The inclusion-induced internal stress decreased exponentially along the radial direction. However, the internal stress, though reduced to a small magnitude, was unexpectedly maintained and propagated over long distances. A stress localization phenomenon, which was out of the prediction of classic elasticity theory, was also observed. The inclination of threading dislocations was found to be substantially influenced by the unreported distribution of internal stress. Four characteristic dislocation inclination patterns were identified: the two-short-tooth pattern, two-long-tooth pattern, gear pattern, and sun-like pattern. The dependence of internal stress on the dislocation inclination pattern was revealed. Based on this dependence, a method to predict the stress field in crystal based on dislocation pattern without corrosion was proposed.

CFD simulation of impeller shape effect on the solid cloud volume in the solid and liquid stirred vessel

Phase transition induced inherent superhydrophobicity on Al alloys surface via femtosecond laser multi-scanning process

Fabrication of biomimetic superhydrophobic metals has attracted considerable interest because of their exceptional surface wettability. Conventional methods for achieving this property often rely on additional organic coatings to lower the surface energy; however, they are very prone to chemical decomposition and even flaking during practical usages. Here, we demonstrated that the laser-induced phase transition in hierarchical structures of metal surface can act as an effective approach to directly produce the superhydrophobic effect without any organic decorations. Through gradual increasing numbers of the femtosecond laser processing, we transfer the surface structures from the initial polycrystalline material into the super-nanometer-sized dual-phase and three-phase material that consists of nano and para-crystallinity embedded in amorphous substance, both of which contribute to lowering the surface energy. Meanwhile, the geometrical profiles of the surface structures become richer and more complicated for improving the stability of air pockets. Remarkably, it is found that both the mechanical and chemical durability of such superhydrophobic surfaces are enhanced significantly for the three-phase based material. This study describes the great value of the metal phase transition in achieving the inherent superhydrophobic properties, which provides a different route to develop high-performance coating-free superhydrophobic surfaces.

Association between METS-IR index and obstructive sleep apnea: evidence from NHANES

Plasmonic properties of gold nanoparticle arrays fabricated using a sequential dewetting process

A scalable, cost-effective technique to fabricate ordered gold nanoparticle arrays with fine control over nanoparticle size and interparticle distance is presented. The array is grown in the pores of an anodic aluminum oxide membrane by the solid-state dewetting process. Control over the nanoparticle size and spacing between particles was achieved by sequential metal deposition and annealing processes, yielding nanoparticles with diameters (D) ranging from 50 to 70 nm and corresponding interparticle distances ranging from 12 to 30 nm. The advantage of this technique is that the nanoparticle size, spherical shape, and hexagonal close-packed ordering of the array can be precisely controlled, allowing for fine tuning of the plasmonic absorption properties. The important parameters that determine the size, shape, and distribution of nanoparticles in the array are the template morphology (dimple geometry) and the thickness of the evaporated metal layer. Above a certain critical film thickness, the nanoparticles coalesce to form nano-islands. The significance of this work is that it provides a reliable technique to assemble metal nanoparticles into high density arrays, with good control over particle shape and distribution. Such arrays can be used to generate highly concentrated electromagnetic fields for plasmonic sensor applications.

Simultaneous screening of 211 pesticide residues in date fruits in Iran and health risk assessments based on Mont Carlo simulation

Boosting low-pressure reversible barocaloric effect in plastic crystal KPF6 through controlled particle size

Plastic crystals have large entropy change during first-order phase transitions due to strong molecular orientation disorder and volume changes. This feature has revived interest in plastic crystals, as they have great potential in solid-state refrigeration applications induced by external pressure. However, the reversible barocaloric effect in most plastic crystals does not compare favorably with their isothermal entropy change. Here, we demonstrate that controlling the particle size of the plastic crystal KPF6 can help achieve a compromise between the phase transition resistance at grain boundaries and the phase transition correlation within grains and induce a giant reversible barocaloric effect at low pressure. In particular, the 75–150 μm plastic crystal KPF6 displays the lowest thermal hysteresis, with a giant reversible barocaloric entropy change of 50.0 J · kg−1 · K−1 under a pressure change of 40 MPa. The reversible barocaloric effect can be more than doubled by simply optimizing the microstructures of the plastic crystal KPF6. Our work provides an effective way to enhance the reversible barocaloric effect in plastic crystal materials. We also give insight into the physical mechanism that enhances the reversible barocaloric effect through transmission electron microscopy analysis.

The intelligent fault identification method based on multi-source information fusion and deep learning

Active rheology of soft solids performed with acoustical tweezers

Single-beam acoustical tweezers are used to manipulate individual microbubbles and provide quantitative measurements of the local shear modulus of soft hydrogels. The microbubbles are directly generated by electrolysis of the hydrogel, and their displacement is detected using optical microscopy in the focal plane of a focused vortex beam. Microbubbles displaced off-axis can be pulled by a restoring radial force component that forms a stable two-dimensional trap. We also observe an off-axis tangential microbubble motion that is due to the transfer of the beam's angular momentum flux. A simple elastic model for the hydrogel deformation combined with radiation force calculations finally provides local values of the medium's shear modulus, which are found to be in good agreement with standard bulk measurements performed with a rheometer. Our results suggest that acoustical tweezers are relevant tools to characterize the local mechanical properties of complex soft materials, opening opportunities in the field of active rheology.

Cyclically symmetric radially self-similar phononic pseudocrystal isolator for broadband, ultrasonic vibration bandstop filtering

A 2D phononic pseudocrystal isolator exhibiting cyclic symmetry and radial self-similarity is measured and demonstrated to block a wide range of ultrasonic vibration. Measurements of longitudinal and shear wave blocking effects are made and compared with computational results. The use of the bandgap edge ratio is recommended for quantifying suppression in very-wide-bandgap materials. The upper-to-lower suppression edge frequency ratios of 3–4 are remarkably large for shear waves and even larger for longitudinal waves upper-to-lower suppression ratio (13 at 5 dB), such that 92.5% of frequencies in that range experience ≥ 5 dB of suppression.

Circularly polarized cavity mode emission from quantum dots in a semiconductor three-dimensional chiral photonic crystal

We experimentally demonstrated a circularly polarized cavity mode in a GaAs-based chiral photonic crystal (PhC) containing a planar defect. Low-temperature photoluminescence measurements of InAs quantum dots (QDs) embedded in the planar defect revealed a polarization bandgap for left-handed circularly polarized light in the near-infrared spectrum. Within this bandgap, where the QDs preferably emitted right-handed circularly polarized light, we observed a distinct cavity mode peak characterized by left-handed circular polarization (CP). This observation indicates that the chiral PhC modifies the optical density of states for left-handed circular polarization to be suppressed in the polarization bandgap and be largely enhanced at the cavity mode. The results obtained may not only provide photonic devices such as compact circularly polarized light sources but also promote strong coupling between circularly polarized photons and excitons in solid states or molecules, paving the way for advancements in polaritonics, spintronics, and quantum information technology.