Browse Articles

Modulating single molecular electron sources with light: Opportunities and challenges

Applying a strong, constant electric field at single-C60 molecule protrusions formed on a metallic substrate can cause electrons to be emitted from individual single molecules into a vacuum. The shapes of such single molecular electron sources reflect the shapes of the molecular orbitals from which the electrons originate. By illuminating the source with light pulses, photo-excited electrons can be emitted from different molecular orbitals, thereby modulating the electron sources at a subnanometric scale. In this context, we discuss the opportunities presented by this light-induced modulation of electron emission for developing a unique scheme to integrate ultrafast switches into a single molecule and for advancing high-resolution, ultrafast electron microscopy. We also discuss the experimental and theoretical challenges associated with this approach, such as the requirements for picoscale stability and controllability of molecular positions, as well as the need for large-scale ab initio calculations under strong constant fields.

Determination of antibacterial and antioxidant potential of organic crude extracts from Malus domestica, Cinnamomum verum and Trachyspermum ammi

Termination-acidity tailoring of molybdenum carbides for alkaline hydrogen evolution reaction

Temperature characteristics of a photoinduced blackbody in intense light fields

A “whitebody” can transform into a “blackbody” under intense light exposure, and the temperature of photoinduced blackbodies deviates significantly from Planck's law. This discovery necessitates the consideration of light excitation's impact on the radiation spectrum of a blackbody when applying Planck's formula. Under the adiabatic approximation, this paper theoretically derives the relationship between the temperature of photoinduced blackbodies and the intensity of excitation light field. The actual temperature of a photoinduced blackbody is directly proportional to the fourth root of the excitation light power. Experimental data demonstrate that this relationship can more accurately describe the temperature characteristics of a photoinduced blackbody in intense light fields. These results provide a theoretical foundation for further investigation into photoinduced blackbody radiation, contribute to an enhanced comprehension of the underlying physical mechanism behind this phenomenon, and may have significant implications for celestial temperature measurements based on Planck's law.

Mental Health and Associated Factors among Bangladeshi Migrants in Thailand: a cross-sectional study

Multi-channel learning for integrating structural hierarchies into context-dependent molecular representation

AbstractReliable molecular property prediction is essential for various scientific endeavors and industrial applications, such as drug discovery. However, the data scarcity, combined with the highly non-linear causal relationships between physicochemical and biological properties and conventional molecular featurization schemes, complicates the development of robust molecular machine learning models. Self-supervised learning (SSL) has emerged as a popular solution, utilizing large-scale, unannotated molecular data to learn a foundational representation of chemical space that might be advantageous for downstream tasks. Yet, existing molecular SSL methods largely overlook chemical knowledge, including molecular structure similarity, scaffold composition, and the context-dependent aspects of molecular properties when operating over the chemical space. They also struggle to learn the subtle variations in structure-activity relationship. This paper introduces a multi-channel pre-training framework that learns robust and generalizable chemical knowledge. It leverages the structural hierarchy within the molecule, embeds them through distinct pre-training tasks across channels, and aggregates channel information in a task-specific manner during fine-tuning. Our approach demonstrates competitive performance across various molecular property benchmarks and offers strong advantages in particularly challenging yet ubiquitous scenarios like activity cliffs.

Electrical control of exchange bias in Fe3GaTe2/Fe3GeTe2 van der Waals heterostructures

Magnetic heterojunctions with large exchange bias have promising applications in magnetic sensing and data storage. Ferromagnetic/antiferromagnetic (FM/AFM) heterojunctions are often used to generate exchange bias. However, the requirement of thermal manipulation makes controlling exchange bias in FM/AFM heterojunctions inconvenient. Herein, a Fe3GeTe2/Fe3GaTe2 FM/FM heterojunction is constructed to generate large exchange bias and reflected magnetic circular dichroism and magneto-optical Kerr effect techniques are used for the magnetic characterization of the heterojunction. The results show that strong magnetic coupling occurs at the Fe3GeTe2/Fe3GaTe2 interface when the temperature is <80 K. By fixing the spin direction of Fe3GaTe2, large exchange bias can be generated in Fe3GeTe2 because of the magnetic pinning effect. Furthermore, the strength of exchange bias can be manipulated by applying an ultralow current between Fe3GeTe2 and Fe3GaTe2 layers without changing the temperature. These results provide potential ways for generating and manipulating exchange bias in two-dimensional (2D) materials and pave the way for implementing the 2D van der Waals exchange bias effect in spintronic devices.

Spin and valley dependent transport and tunneling magnetoresistance in irradiated ferromagnetic WSe2double barrier junctions

AbstractSpin and valley polarizations (Ps and PKK’) and tunneling magnetoresistance (TMR) are demonstrated in the ferromagnetic/barrier/normal/barrier/ferromagnetic WSe2 junction, with the gate voltage and off-resonant circularly polarized light (CPL) applied to the two barrier regions. The minimum incident energy of non-zero spin- and valley-resolved conductance has been derived, which is consistent with numerical calculations and depends on the electric potential U, CPL intensity ΔΩ, exchange field h, and magnetization configuration: parallel (P) or antiparallel (AP). For the P (AP) configuration, the energy region with PKK’ = -1 or Ps = 1 is wider (narrower) and increases with ΔΩ. As h increases, the Ps = 1 (PKK’ = -1 or Ps = 1) plateau becomes wider (narrower) for the P (AP) configuration. As U increases, the energy region with PKK’ = -1 increases first and then moves parallel to the EF-axis, and the energy region with Ps = 1 for the P configuration remains unchanged first and then decreases. The energy region for TMR = 1 increases rapidly with h, remains unchanged first and then decreases as U increases, and has little dependence on ΔΩ. When the helicity of the CPL reverses, the valley polarization will switch. This work sheds light on the design of spin-valley and TMR devices based on ferromagnetic WSe2 double-barrier junctions.

GmERF13 mediates salt inhibition of nodulation through interacting with GmLBD16a in soybean

Multihyperuniformity in high-entropy MXenes

MXenes are a large family of two-dimensional transition metal carbides and nitrides that possess excellent electrical conductivity, high volumetric capacitance, great mechanical properties, and hydrophilicity. In this work, we generalize the concept of multihyperuniformity, an exotic state that can exist in a disordered multi-component system, to MXenes. Disordered hyperuniform systems possess an isotropic local structure that lacks traditional translational and orientational order, yet they completely suppress infinite-wavelength density fluctuations as in perfect crystals and, in this sense, possess a hidden long-range order. In particular, we evaluate the static structure factor of the individual components present in the high-entropy (HE) MXene experimental sample TiVCMoCr based on high-resolution scanning electron microscope imaging data, which suggests that this HE MXene system is at least effectively multihyperuniform (MH). We then devise a packing algorithm to generate MH models of HE MXene systems. The MH HE MXenes are predicted to be energetically more stable compared to the prevailing (quasi)random models of the HE MXenes due to the hidden long-range order. Moreover, the MH structure exhibits a distinctly smaller lattice distortion, which has a vital effect on the electronic properties of HE MXenes, such as the density of states and charge distribution. This systematic study of HE MXenes strengthens our fundamental understanding of these systems and suggests possible exotic physical properties, as endowed by the multihyperuniformity.

Construction and validation of a nomogram predictive model for assessing the risk of surgical site infections following posterior lumbar fusion surgery

Rapid and quantitative functional interrogation of human enhancer variant activity in live mice

Abstract Functional analysis of non-coding variants associated with congenital disorders remains challenging due to the lack of efficient in vivo models. Here we introduce dual-enSERT, a robust Cas9-based two-color fluorescent reporter system which enables rapid, quantitative comparison of enhancer allele activities in live mice in less than two weeks. We use this technology to examine and measure the gain- and loss-of-function effects of enhancer variants previously linked to limb polydactyly, autism spectrum disorder, and craniofacial malformation. By combining dual-enSERT with single-cell transcriptomics, we characterise gene expression in cells where the enhancer is normally and ectopically active, revealing candidate pathways that may lead to enhancer misregulation. Finally, we demonstrate the widespread utility of dual-enSERT by testing the effects of fifteen previously uncharacterised rare and common non-coding variants linked to neurodevelopmental disorders. In doing so we identify variants that reproducibly alter the in vivo activity of OTX2 and MIR9-2 brain enhancers, implicating them in autism. Dual-enSERT thus allows researchers to go from identifying candidate enhancer variants to analysis of comparative enhancer activity in live embryos in under two weeks.

Overlap-scanning self-referencing diffractive imaging with enlarged field of view under incoherent illumination

Coherent diffractive imaging (CDI), especially the ptychography, has been widely used in quantitative phase imaging. However, in traditional diffractive imaging schemes, a highly coherent light source is required for a better-posed inverse problem. Considering that the high coherence cannot be guaranteed in all cases and to avoid the multi-mode of low-coherence light sources complicating the iterative modeling of diffractive imaging, we proposed an overlap-scanning self-referencing diffractive imaging. As a non-iterative partially coherent diffractive imaging method, self-referencing diffractive imaging was combined with the procedure of overlap-scanning ptychography. It does not require prior knowledge of light source coherence, and only a coherent inverse problem was needed to be solved in the final stitching. It has been demonstrated to be able to recover the complex amplitude of objects illuminated by various low-coherence light sources. This study presents significant potential for applications in phase imaging with a wide-field of view under incoherent illuminations.

Knockout or inhibition of DHPS suppresses ovarian tumor growth and metastasis by attenuating the TGFβ pathway

Tracing ancient solar cycles with tree rings and radiocarbon in the first millennium BCE

AbstractThe Sun drives Earth’s energy systems, influencing weather, ocean currents, and agricultural productivity. Understanding solar variability is critical, but direct observations are limited to 400 years of sunspot records. To extend this timeline, cosmic ray-produced radionuclides like 14C in tree-rings provide invaluable insights. However, few records have the resolution or temporal span required to thoroughly investigate important short-term solar phenomena, such as the 11-year solar cycle, or 14C production spikes most likely linked to solar energetic particle (SEP) events. Here we present a continuous, annually resolved atmospheric 14C record from tree-rings spanning the first millennium BCE, confirming no new SEP’s and clearly defining the 11-year solar cycle, with a mean period of 10.5 years, and amplitude of approximately 0.4‰ in 14C concentration. This dataset offers unprecedented detail on solar behavior over long timescales, providing insights for climatic research and solar hazard mitigation, while also offering enhanced radiocarbon calibration and dating accuracy.

Dynamic domain motion enhancing electro-optic performance in ferroelectric films

With the rapid advancement of information technology, there is a pressing need to develop ultracompact and energy-efficient thin-film-based electro-optic (EO) devices. A high EO coefficient in ferroelectric materials is crucial. However, substrate clamping can positively or negatively influence various physical properties, including the EO response of these films, thus complicating the development of next-generation thin-film-based devices. This study demonstrates that reversible dynamic domain motion, achieved through substrate clamping, significantly enhances the EO coefficient in epitaxial ferroelectric rhombohedral Pb(Zr, Ti)O3 thin films, where the (111) and (111¯) domains coexist with distinct optical axes. In principle, this approach can be applied to different film-substrate systems, thereby contributing to the advancement of sophisticated EO devices based on ferroelectrics.

Nanotechnology and LSTM machine learning algorithms in advanced fuel spray dynamics in CI engines with different bowl geometries

Factors governing $${\rm H}_{3}^{+}$$ formation from methyl halogens and pseudohalogens

4780 nm ultra-broadband entangled biphotons from a chirped PPLN

Ultra-broadband frequency entangled biphotons have exceptionally short temporal duration and can achieve narrow Hong–Ou–Mandel (HOM) interference patterns, making them vital for quantum metrology applications. However, the bandwidth of previously demonstrated biphotons used for HOM interference has been limited to less than 400 nm, which is not wide enough to achieve ultra-high precision in quantum metrology. In order to push the precision to its limit, we have theoretically designed a 20-mm-long chirped periodically poled lithium niobate (CPPLN) crystal with type-II phase matching. Pumped by a 405 nm laser, the down-converted signal and idler photons can cover the wavelength range from 420 to 5200 nm, approaching the transparent upper bound of the LN crystal. In the simulated Hong–Ou–Mandel (HOM) interference, the full-width at half-maximum of the interference pattern is 965 attoseconds, with a visibility of 99.44%. Following a similar approach, we also designed a type-0 CPPLN crystal to achieve higher brightness. These ultra-broadband biphoton sources can generate ultra-narrow quantum interference patterns, which have the potential for attosecond-level high-precision quantum metrology.

Seepage mode in lamina-developed shale oil reservoirs under strong heterogeneous and strong fluid–solid coupling in Jiyang depression of China