Optical skyrmions are topological textures of electromagnetic fields with promising applications in information processing, transport, and storage. Exquisitely tailoring the optical fields of diverse physical quantities has expanded the family of skyrmions, yet such skyrmions only exhibit a single-quantity texture in free space. Herein, dual skyrmionic textures concurrently portraying spin and Poynting vectors are unveiled in the tight focus of an annular second-order circularly polarized vortex beam. The focal electric and magnetic fields exhibit an elongated and identical spatial distribution but a phase difference of π/2, leading to dual skyrmionic textures with vector orientations that are either opposite or identical, depending on the handedness of the incident beam. Unlike conventional optical skyrmions that are exclusively regarded as quasiparticles distributed in a two-dimensional plane, a skyrmionic tube structure that extends over a longitudinal depth approaching 10λ while preserving its topology is demonstrated. Our Letter enhances the comprehensiveness of optical skyrmions and paves the way toward their practical applications by bolstering skyrmion-matter interactions.

Exploring new ways to introduce the ferroelectricity into well-known non-ferroelectric materials can greatly promote the development of ferroelectric materials and devices. Here we demonstrate an unusual room-temperature ferroelectricity induced by nanotwins in a rutile TiO2 (R-TiO2) thin film, which has an extremely high density of nanotwins with typical twin width < 2 nm. The coercive field are measured to be similar to 50 kV/cm. Aberration-corrected transmission electron microscopy observations and first-principles calculations reveal that the TiO6 octohedra at the {011} R-TiO2 twin boundaries are non-centrosymmetric and the Ti4+ ions deviate significantly from the centers of octohedra, thereby resulting in the ferroelectricity of nanotwinned R-TiO2 thin film. Photocatalytic water-splitting measurements reveal that the H-2 production efficiency of the ferroelectric nanotwinned R-TiO2 thin film is about 10 times that of the R-TiO2 single crystal. The strategy of introducing the ferroelectricity by nanotwins should be in principle applicable in other oxides with low twin formation energy, opening an avenue toward grain-boundary-induced ferroelectricity.

With the rapid advances of optical information technology, numerous optical systems in both scientific and industrial fields are pursuing a resolution that surpasses the classical diffraction limit. Super-resolving pupil filters, whose transmittance or phase can be spatially modulated, have attracted intense interest for squeezing the focal spot of optical systems through wavefront manipulation, and have also been implemented in the fields of optical microscopy, optical storage, telescopes, etc. However, all the previously reported super-resolving pupil filters are tailored exclusively to specific optical systems with fixed focal lengths, rendering them incompatible with zoom or variable-focus optical platforms. In this work, we introduce a multi-adaptive super-resolving pupil filter that retains sub-diffraction-limited performance across a range of variable focal lengths. Such a pupil filter is composed of concentric annular belts in a binary phase configuration, designed via a two-step optimization algorithm and fabricated by using the ultraviolet optical lithography technique. Both numerical simulation and experimental results demonstrate that the sub-diffraction-limited focal spot can be consistently yielded at the designed wavelength of 633 nm when the super-resolving pupil filter is paired with plano-convex lenses of 50 mm,75 mm,100 mm, and 150 mm focal lengths, respectively. As a proof-of-concept demonstration, we integrate the filter into an optical imaging system and experimentally verify its resolution enhancement performance over the full focal-length range. Owing to its planar geometric structure and negligible insertion loss, the proposed multi-adaptive super-resolving pupil filter offers a practical way for the development of super-resolution zoom microscopy and zoom telescopes.

A supercritical lens(SCL)can achieve far-field sub-diffraction-limited focusing by elaborately manipulating the interference effect in the focal region,which makes it strongly dependent on the wavelength of the illuminating light.In addition to the strong chromatic aberrations it suffers,the micrometer-scale clear aperture of reported SCL represents another compelling challenge that excludes their practical imaging applications demand.In this work,we proposed and experimentally demonstrated an achromatic supercritical lens(ASCL)with a centimeter-scale clear aperture.The ASCL was designed by a two-step optimization algorithm and constructed in a multilevel phase configuration which consists of 1251 concentric polymer rings with 52 phase levels.By utilizing the gray-scale laser lithography technique,we successfully fabricated an ASCL with a diameter of 10 mm.Such a centi-meter-scale ASCL showcases a distinguished performance with full visible working bandwidth covering from 400 nm to 700 nm and simultaneous achromatic sub-diffraction-limited focusing of 0.88 times of the Airy spot.The demonstrations of white light microscopic imaging further validate our design and show decent performance.Our work paves the way for practical applications of SCL in high-density optical data storage,super-resolving optical telescope,and high-precision optical trapping.

Elemental doping at coherent interfaces is very difficult and rarely used to improve the interfacial properties since coherent interfaces have low interfacial energies and lack open space for trapping dopant atoms. Exploring universally applicable strategies for elemental doping at coherent interfaces represents an important progress in interface science and engineering. In this study, Nb atoms are successfully doped at coherent (001) LaAlO3/ anatase-TiO2 interfaces, which enhances greatly the efficiency of photocatalytic hydrogen production from water. Transmission electron microscopy investigations reveal that both LaO- terminated and AlO2-terminated LaAlO3/anatase-TiO2 interfaces can trap two layers of Nb atoms, which accompanies with the formation of La vacancies between them. First-principles calculations suggest that Nb atoms segregate at the interfaces under the action of potential gradient, which increases significantly the strength of the built-in electric field in TiO2, thereby facilitating the separation of photogenerated carriers and improving the photocatalytic performance. The H2 production of the Nb doped coherent interface is about 4 times that of the pristine coherent interface. Since potential gradient widely exists at various interfaces including the coherent ones, elemental doping by potential gradient should be an universally applicable fabrication method for tuning the properties of interfaces and heterostructures.

Planar metalenses have distinct advantages over their traditional bulky refractive lens in terms of being lightweight and integrable. Their remarkable ability to modulate the phase and amplitudes of incident light without restrictions offers a revolutionary approach for a multitude of frontier applications. In recent years, tunability has become a prominent direction to pursue for the investigation of planar metalens. However, existing studies on tunable metalenses predominantly concentrate on adjusting the focal length to achieve zooming effects in optical imaging, while less attention has been dedicated to the tunability of the focal field itself. This aspect, if explored, could significantly broaden the scope and flexibility of their applications, particularly in multi-mode optical imaging. In this work, a flexible and stretchable metalens is proposed and theoretically demonstrated for the dynamic tuning of the focal field morphology. To fulfill the phase requirement during dynamic modulation, the diatomic coupled resonator is applied as the basic element, which possesses higher-order freedom of phase modulation capability. Through the symmetry reforming process by transverse stretching along the horizontal direction, the focal field of the metalens can be converted from a diffraction-limited airy spot into a uniform transverse optical needle. The length of the transverse optical needle can be precisely tailored according to the degree of deformation of the metalens. This research presents a method for light field modulation and holds extensive potential for applications in dual-mode laser-scanning confocal microscopy, laser processing, optical manipulation, etc.

Rutile/Anatase (R/A) biphase TiO2 has superior photocatalytic performance than its single-phase counterpart due to the effect of interface band alignment. However, two crucial issues remain unresolved: First, the controllable growth of epitaxial R/A TiO2 with unburied interfaces is extremely challenging. Second, the direction of electron flow is full of controversy since the atomic and electronic structures of the R/A interface have not been experimentally obtained. Here a controllable growth of lateral R/A biphase TiO2 superlattice on stepped LaAlO3 substrates is demonstrated. The R-TiO2 nucleates at the steps of substrate while the A-TiO2 grows on the terraces. It is revealed that the R/A interface has a built-in electric field and a reduced band gap. Photogenerated electrons flow toward A-TiO2 due to its higher electron affinity. The lateral R/A biphase TiO2 superlattice exhibits outstanding water-splitting performance and may find applications in other fields. The strategy of step-assisted growth of lateral biphase superlattice should be applicable for other compounds with polymorphs.

Achieving high-efficiency photocatalytic overall water splitting with earth-abundant materials like TiO2 under ambient conditions is a compelling renewable energy solution. However, this remains challenging due to both the presence of rich deep-level defects and lack of strong driving force in particulate photocatalysts, limiting the separation of photogenerated charges. Here, we developed a scandium (Sc)-doped rutile TiO2 with fully passivated detrimental Ti3+ defects and very strong built-in electric field arising from engineered (101)/(110) facet junctions. The Sc3+ doping enables a much lower exciton binding energy of 8.2 meV (28.6 meV for undoping) than room-temperature thermal fluctuation energy, indicating spontaneous exciton dissociation. These features enable the photogenerated electrons and holes to selectively transfer to the (110) and (101) facets, respectively. The resulting Sc-doped TiO2 with cocatalyst delivers photocatalytic overall water splitting with an apparent quantum yield of 30.3% at 360 nm and a solar-to-hydrogen conversion efficiency of 0.34%, representing the highest values reported for TiO2-based photocatalysts under ambient conditions.

Biphase TiO2 outperforms its single-crystal polymorphs in the field of photocatalysis because of the homojunction effect. However, most studies of biphase TiO2 focused on nanoparticles or powders. Growth of biphase TiO2 thin films remains a substantial challenge. In this study, biphase TiO2 thin films were epitaxially grown on SrTiO3 (111) substrates by using pulsed laser deposition. Transmission electron microscopy observations revealed that the R-TiO2 grains possessed six variants with a rotation angle of 60 degrees since the Sr-O and Ti-terminated surfaces had three epitaxial relationships with the R-TiO2 phase, respectively. The A-TiO2 grains nucleated at the steps of the substrate and formed three variants with a rotation angle of 120 degrees. Charge transfer measurements revealed that the biphase TiO2 film was superior to the single-crystal A-TiO2 film. These results suggest that the epitaxial biphase TiO2 film can be directly grown on a SrTiO3 (111) substrate, which will be beneficial for its real applications.

Organic magnetic semiconductors have aroused much attention for spintronic applications. However, it remains challenging to achieve organic semiconductors with strong room-temperature ferromagnetism. Here, we report a two-dimensional (2D) tetragonal organic-inorganic ferrimagnetic (FIM) semiconductor of Fe14Se16(peha)0.7 (peha = pentaethylenehexamine) with excellent thermal stability and a Curie temperature (TC) higher than 519 K. Magnetic and M & ouml;ssbauer measurements reveal a long-range magnetic ordering in single crystalline Fe14Se16(peha)0.7 nanosheets. The saturation magnetization and coercivity are 5.9 emu g-1 and 0.42 kOe at 5 K, which slightly reduces to 4.6 emu g-1 and similar to 0 Oe at 300 K. A direct optical bandgap of 2.22 eV is obtained by tuning electronic structure of beta-Fe3Se4 host layers through spacer layers consisting of Fe3+ and peha. Electrical and Seebeck coefficient data indicate that the n-type semiconductor follows the thermally-activated conduction mechanism (ln rho proportional to T-1) in a range of 130-300 K with an activation energy ( Ea ) of 62.69 meV. Thermal conductivity is 2.5 W m-1 K-1 at 300 K, while the Wiedemann-Franz law is strongly violated according to electrical-thermal transport data due to weak incorporation of organic spacer layers and host layers. This study sets the stage for exploiting new room-temperature organic magnetic semiconductor systems for spintronic materials. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Multiplexing information in light’s fundamental attributes to create supplementary orthogonal data channels has been well heralded as an effective means for optical data storage with greatly enhanced capacities. However, robust decoding methods against inevitable crosstalks associated with experimental noise and writing imperfections as the increase of multiplexing dimensions represent a major hurdle preventing the effective practice of multi-dimensional optical recording. Here, we propose a deep-learning-based retrieval approach for robust decoding multiplexed information. An artificial neural network is trained to learn the crosstalks from multiplexed recording in disordered gold nanorod aggregates with loosened orthogonality constraints. The acquired raw readout images are analyzed by the trained neural network, which allows quick, high-fidelity, and reliable information retrieval from polarization-, wavelength-, and 3D spatially multiplexed data. The smart decoding protocol paves the way toward the mass-production ready and wide-spread application of high-capacity multi-dimensional optical storage.

In the past decade, ferroelectric materials have been intensively explored as promising photocatalysts. An intriguing ability of ferroelectrics is to directly sperate the photogenerated electrons and holes, which is believed to arise from a spontaneous polarization. Understanding how polarization affects the photocatalytic performance is vital to design high-efficiency photocatalysts. In this work, we report a size effect of ferroelectric polarization on regulating the photocatalytic overall water splitting of SrTiO3/PbTiO3 nanoplate heterostructures for the first time. This was realized hydrothermally by controlling the thickness and thus spontaneous polarization strength of single-crystal and single-domain PbTiO3 nanoplates, which served as the substrate for selective heteroepitaxial growth of SrTiO3. An enhancement of 22 times in the photocatalytic overall water splitting performance of the heterostructures has been achieved when the average thickness of the nanoplate increases from 30 to 107 nm. A combined experimental investigation revealed that the incompletely compensated depolarization filed is the dominated driving force for the photogenerated carrier separation within heterostructures, and its increase with the thickness of the nanoplates accounts for the enhancement of photocatalytic activity. Moreover, the concentration of oxygen vacancies for negative polarization compensation has been found to grow as the thickness of the nanoplates increases, which promotes oxygen evolution reaction and reduces the stoichiometric ratio of H2/O2. These findings may provide the opportunity to design and develop high-efficiency ferroelectric photocatalysts.

BackgroundExercise is recognized for its broad health benefits, influencing various physiological processes, including the behavior of adipose tissue macrophages (ATMs). While existing studies mainly associate ATM activity with obesity and metabolic syndrome, our study explores the impact of aerobic exercise on ATM microRNA expression profiling in a non-obese context, highlighting its general health-promoting mechanisms.MethodsSixty male C57BL/6 mice were randomly assigned to either a sedentary (S) or an exercise (E) group. The S group remained inactive, while the E group underwent a one-week treadmill adaptation, followed by an 8-week aerobic treadmill exercise protocol (60 min/day, 5 days/week, at 65%-75% VO2max). Post-training, glucose tolerance and the serum lipid levels were measured in mice subjected to both exercise and non-exercise conditions. ATMs harvested from visceral adipose tissues were analyzed and sorted using flow cytometer. To further investigate the effects of exercise in ATMs at the molecular level, miRNA microarray analysis was performed, followed by bioinformatic analysis.ResultsThe 8-week regimen of moderate-intensity aerobic exercise ameliorated glucolipid metabolism and fostered a dynamic shift toward an M2 macrophage phenotype in the adipose tissue, independent of obesity. A total of 62 differentially expressed miRNAs were identified in ATMs of mice post-exercise. Notably, six miRNAs (miR-212-5p, miR-511-5p, miR-7b-5p, miR-142-3p, miR-1894-3p, and miR-31-5p) as well as their target gene were consistently altered and associated with macrophage polarization and metabolic regulation.ConclusionOur findings broaden the understanding of how exercise regulates ATM functions through significant changes in microRNA profiles, emphasizing its potential to enhance health and prevent chronic conditions. This study supports the application of aerobic exercise for its preventive effects on chronic diseases and underscores the importance of microRNA profiling in understanding the immune-modulatory impacts of exercise.

Multi-focusing of light is a crucial capability for photonic devices that can be effectively achieved by precisely modulating the phase delay on the incident wavefront. However, integrating functional structures into optical fibers for remote light focusing remains challenging due to the complex device design and limited fabrication approaches. Here, we present the design and fabrication of metalens array on the end-face of a tailored single-mode step-index fiber for focusing light field into closely packed focal spot array. The metalenses are configured based on the fractional Talbot effect and benefit a modular design capability. Light passing through the optical fiber can be focused into different focal planes. With a synergistic 3D laser nanoprinting technique based on two-photon polymerization, high-quality meta-fibers are demonstrated for focusing light parallelly with a uniform numerical aperture (NA) as high as approximately 0.77. This may facilitate various applications such as optical trapping, generation of sophisticated beam profiles, and boosting light coupling efficiencies.

The 3D structured light field manipulated by a digital-micromirror-device (DMD)-based digital hologram has demonstrated its superiority in fast-fabricating stereo nanostructures. However, this technique intrinsically suffers from defects of light intensity in generating modulated focal spots, which prevents from achieving high-precision micro/nanodevices. In this Letter, we have demonstrated a compensation approach based on adapting spatial voxel density for fabricating optical metalenses with ultrahigh precision. The modulated focal spot experiences intensity fluctuations of up to 3% by changing the spatial position, leading to a 20% variation of the structural dimension in fabrication. By altering the voxel density to improve the uniformity of the laser cumulative exposure dosage over the fabrication region, we achieved an increased dimensional uniformity from 94.4% to 97.6% in fabricated pillars. This approach enables fast fabrication of metalenses capable of sub-diffraction focusing of 0.44λ/NA with the increased mainlobe–sidelobe ratio from 1:0.34 to 1:0.14. A 6 × 5 supercritical lens array is fabricated within 2 min, paving a way for the fast fabrication of large-scale photonic devices.

Topological properties of energy flow of light are fundamentally interesting and have rich practical applications in optical manipulations. Here, skyrmion-like structures formed by Poynting vectors are unveiled in the focal region of a pair of counter-propagating cylindrical vector vortex beams in free space. A N\'eel-Bloch-N\'eel skyrmion type transformation of Poynting vectors is observed along the light propagating direction within a volume with subwavelength feature sizes. The corresponding skyrmion type can be determined by the phase singularities of the individual components of the coherently superposed electromagnetic field in the focal region. This work reveals a new family member of optical skyrmions and may introduce novel physical phenomena associated with light scattering and optical force.

Ultrafine alumina is widely used in advanced manufacturing industry, and its form, size and dispersion have important effects on its physicochemical properties and application characteristics. However, the superfine monodisperse spherical alumina is difficult to obtain in the actual synthesis process because the alumina precursor grain grows too fast and is easy to agglomerate. In this work, ammonium sulfate was added as the synthetic raw material to improve its dispersity. When the concentration reached 40 % of the aluminum source concentration, the isometric alumina precursor with a particle size of about 35 nm was obtained under the condition of rapid cooling. The influence of ammonium sulfate on the chemical structure of the precursor was determined by Fourier Transform Infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS). The effects of reactant concentration and reaction temperature on the morphology, particle size and dispersion of the precursor as well as its mechanism were discussed in detail, and the optimal synthesis method of the nano alumina precursor was obtained. Finally, two kinds of precursors were calcined at different temperatures to obtain the equiaxed gamma-Al2O3 with a particle size of 20 nm and the monodisperse spherical alpha-Al2O3 with a particle size of 133 nm, respectively. In this study, nano alumina precursors were synthesized by a simple and reliable method, and monodisperse ultra-fine alumina with different particle size morphologies were obtained, which has great application prospects in precision polishing, special ceramic manufacturing, and 3D printing.

Few-layer transition metal dichalcogenides (TMDs) and their combination as van der Waals heterostructures provide a promising platform for high-performance optoelectronic devices. However, the ultrathin thickness of TMD flakes limits efficient light trapping and absorption, which triggers the hybrid construction with optical resonant cavities for enhanced light absorption. The optical structure enriched photodetectors can also be wavelength- and polarization-sensitive but require complicated fabrication. Herein, a new-type TMD-based photodetector embedded with nanoslits is proposed to enhance light trapping. Taking ReS2 as an example, strong anisotropic Mie-type optical responses arising from the intrinsic in-plane anisotropy and nanoslit-enhanced anisotropy are discovered. Owing to the nanoslit-enhanced optical resonances and band engineering, excellent photodetection performances are demonstrated with high responsivity of 27 A W-1 and short rise/decay times of 3.7/3.7 ms. More importantly, through controlling the angle between the nanoslit orientation and the polarization direction to excite different resonant modes, polarization-sensitive photodetectors with anisotropy ratios from 5.9 to 12.6 can be achieved, representing one of the most polarization-sensitive TMD-based photodetectors. The depth and orientation of nanoslits are demonstrated crucial for optimizing the anisotropy ratio. The findings bring an effective scheme to construct high-performance and polarization-sensitive photodetectors.