Browse Articles

Enhanced polarization-multiplexed metasurface imaging for secure information encoding

We propose an enhanced polarization-multiplexed metasurface imaging scheme integrated with a visual secret-sharing encryption strategy. Information-bearing images are encoded into a multilayer H-shaped metasurface, establishing the first physical layer of security. Subsequently, the image content is converted into a global encryption key and corresponding user-specific subkeys through pixel overlay, forming the second information layer of protection. To validate the proposed scheme, metasurface samples are fabricated, and experimental results demonstrate robust reconstruction of encrypted images with high fidelity and low crosstalk under different polarization states. This method provides a promising solution for millimeter-wave imaging, physical-layer secure communication, and intelligent encryption applications.

Characterization of sooty blotch and flyspeck fungi on mango (Mangifera indica L.) in Peninsular Malaysia

Enhancing meandering VO2 microwire bolometer sensitivity via confined electron layer

VO2 bolometers offer excellent detection sensitivity, especially when temperature biased close to the transition temperature. We show here that a tunable-sensitivity bolometer with an extended range can be achieved using VO2 thin films using a specially designed gated meander device structure. While the electric field does not influence the transition temperature of the meandering microwire, a two-dimensional confined electron layer is observed to emerge upon the application of a lateral gate field, leading to improved photosensitivity, by up to 50%, over a wide range of incidence laser powers without any external temperature bias. Our results highlight that electric field control in VO2 facilitates low-power operation, underscoring its potential for energy-efficient and long-lasting electronic applications.

Propofol and dexmedetomidine sedation share the similar functional activity but distinct functional synchronization

Fully optical switching memory based on an oxidized GQD–FeOx heterojunction with 106 negative photoconductance ratio

A fully optical control device can provide positive photoconductance memory (PPM) and negative photoconductance memory (NPM), enabling the device to execute fully optical computing. However, the NPM triggering involves complex modulation and small ratio. Here, we propose an oxidized GQD–FeOx heterojunction optoelectronic memory that integrates the PPM and NPM effects into the same cell, thus building all-in-one fully optical computing. The PPM originates from the electrons that are generated from neutral Vo sites under low resistance state while the NPM effect with an ultrahigh ratio of 106 is contributed by the increase in neutral Vo under high resistance state. The theory calculation illustrates that the NPM effect heavily relies on the geometric confinement and partial reflections of the oxidized GQDs and the localization effect of the FeOx. This work provides a significant structure design and photogenerated electron dynamic for the development of fully optical computing.

Engineering properties and microscopic mechanism of phosphogypsum-rubber composite cemented soil

Thermal interface material of carbon fiber enhanced micro-nano Cu sintering for power module thermal management

The pursuit of higher power and density in wide bandgap power modules makes thermal management a critical challenge. Thermal interface materials (TIMs) play a critical role by filling microscopic air gaps and thereby enhancing heat transfer for power electronics. Combining the recent development of nano metal sintering technology and exceptional intrinsic thermal conductivity of certain carbon allotropes, micro-nano Cu sintering with carbon fiber (CF) reinforcement was promoted as potential high performance and cost-effective TIM for power modules. In this work, a Cu/CF composite paste was synthesized and sintered by the thermal-compressing process, followed by the detailed investigation and simulation on its sintered interfacial microstructure and mechanical and thermal properties. This work demonstrated a significant improvement of thermal and mechanical properties through the optimization of CF doping ratio. The addition of 5 wt. % CF increased the average shear strength of Cu sintering joints by 65.3% to 44.8 MPa, which is attributed to enhanced interface adhesion from the nano Ni particle coating on the CF surface. Thermal conductivity rose from 77.1 to 87.4 W/(m K) and 107 W/(m K) with 5 and 10 wt. % CF doped, respectively. Furthermore, adding 10 wt. % CF increased thermal diffusivity by 27.4%, which helps alleviate transient thermal loads. This work highlights the strong potential of Cu/CF composites as future TIM for high-density power modules.

Thermal analysis of flat plate solar air heater system with radiation reflectors and W-shaped roughness: artificial neural network & machine learning approach

Abstract The lower thermal behavior of solar-based thermal systems limits the contribution of solar systems to meet current energy demand of industries. The Flat Plate Solar Air Heater (FPSAH) is extensively utilized in many applications requiring reasonable heat but struggles from inherent limitation in convective heat release and mediocre efficiency. In this study, the challenges are addressed with a novel means of dual mode augmented technique. This mode integrated absorber surface of the FPSAH system by introducing two radiation reflectors on either edge of the rectangular channel. Primarily these reflectors forward back the solar irradiance over the absorber plate, thus increasing the actual solar flux. Simultaneously, a W-shaped artificial rib roughness pattern is merged on the underneath (air-side) of the absorber plate. This coarseness is intended to persuade measured flow disorder inside the channel that disrupt the boundary layer development and may consequently augment convective heat transfer. Experimental testing is conducted with different combinations of roughened absorber surface and radiation reflectors. The performance enhancement is evaluated in terms of Nusselt number ( Nu ) and thermal efficiency of the FPSAH system. The maximum Nu achieved is 1.63 times higher using a set of radiation reflectors along with W-shaped roughness on the absorber surface compared to the plain configuration without radiation reflector. Finally, artificial neural network (ANN) and machine learning (ML) algorithms were used to predict Reynolds number in each set of experiments. A very good curve fitting was achieved by the Robust Regression algorithm with $$R^2 = 0.99$$ for the testing dataset and $$R^2 = 0.94$$ by the Random Forest Regression algorithm for ML.

GaN HEMT with improved electrical performance enabled by hybrid AlN nucleation layers

Herein, a 1.8-μm GaN-on-sapphire high-electron-mobility transistor (HEMT) with superior crystal quality is developed by elaborately modulating the initial nucleation stage of the hybrid AlN nucleation layers (NLs), including both a 25-nm magnetron sputtered AlN and a 60-nm metalorganic-chemical-vapor-deposition-grown AlN (MO-AlN). The hybrid AlN-NL, subjected to an additional in situ thermal annealing process in an H2 atmosphere, not only offers nucleation sites for subsequent HEMT epitaxy but also benefits dislocation annihilation in a GaN buffer with scaled-down thickness. The as-grown GaN buffer layer of the HEMT structure features the full-width-half-maximum values as low as 53 and 179 arc sec for (002) and (102) x-ray rocking curves diffractions, which are among the best crystalline qualities of the (ultra)thin-GaN-buffer structures on sapphire substrates. The as-grown 4-in. HEMT epitaxial layer exhibits a uniform sheet resistance of 309 Ω/□ across the wafer with a 2DEG concentration of 1 × 1013 cm−2 and an electron mobility exceeding 2000 cm2/(V s), serving as a promising platform for the fabrication of GaN HEMTs for power electronics applications.

Qualitative analysis of chemical components in Berberis kaschgarica Rupr. and study on the in vitro anti-inflammatory effects of its alkaloids

A single-layer color router for solid-state image sensors

We present a single-layer color router for solid-state image sensors with 0.5 μm size pixels, which is currently the state of the art in sub-micrometer pixels. Unlike other single-layer approaches, a single-layer color router separates colors directly at its output without the need for additional external propagation. Despite being a significant simplification of an ideal color router, a color router made of a single layer achieves very high optical efficiency (>0.7–0.8) for the red, green, and blue color channels while simultaneously featuring low crosstalk. These results also improve on the predicted performance of single-layer approaches that rely on an additional external propagation distance to separate colors, typically for pixels that are larger than the 0.5 μm shown here. To gain further insight, we show the importance of the non-propagating, near-field contributions for creating highly efficient color separation devices.

Retraction Note: Magnetic and pH sensitive nanocomposite microspheres for controlled temozolomide delivery in glioblastoma cells

Probing optical anisotropy and stability of NbOCl2 and NbOI2 using Mueller matrix spectroscopic ellipsometry

The niobium oxide dihalide family NbOX2 (X = Cl, Br, and I) exhibits strong in-plane anisotropy and hence polarization-dependent properties, making them great candidates for electronic, optoelectronic, and quantum photonic applications. In this work, the dielectric functions of NbOCl2 and NbOI2 nanoflakes were investigated using Mueller matrix spectroscopic ellipsometry. Despite the monoclinic symmetry of the bulk materials, we propose a biaxial orthorhombic optical model and observe an excellent match to the ellipsometry data collected at different azimuth orientations. Density functional theory (DFT) calculations reveal that the principal axes of the dielectric tensor are indistinguishably close to the c and a* axes (the layer normal). Good agreement is also observed in the principal dielectric tensor obtained from DFT calculation and ellipsometry analysis. Onset of absorptions along the principal polar b-axis occurs at higher energies compared to the non-polar c-axis, which defines the material bandgap of 1.75 eV for NbOI2 and 2.1 eV for NbOCl2 nanoflakes. The real part of the dielectric function tends to be higher for NbOI2 than for NbOCl2, in every principal direction. Remarkable linear dichroism was observed from UV to the visible spectral range. NbOCl2 remained optically stable in ambient storage, while the optical properties of NbOI2 changed dramatically over time, indicating material degradation under ambient conditions.

Retraction Note: An assessment of physiological and health responses in Catla catla fingerlings after polystyrene microplastic exposure

Geometric quantum gates of non-closed paths under counterdiabatic driving

We propose a high-fidelity quantum control framework based on the quasi-topological number (νqua), which extends the traditional Chern number to characterize geometric responses in non-closed paths. By introducing an Adiabatic Gauge Potential that dynamically suppresses non-adiabatic transitions and reconstructs path curvature, we demonstrate that νqua—a relative homotopy invariant of compact manifolds in parameter space—quantifies the robustness of geometric phases during open-path quantum evolution. This integer invariant ensures gauge-invariant suppression of decoherence errors arising from dynamical phase coupling. Numerical simulations in the Kitaev superconducting chain and 2D transverse field Ising model confirm that our protocol achieves high quantum gate fidelity. We bridge geometric quantum control with topological protection, offering a universal approach to obtain high-fidelity and robust quantum gates.

An integrated framework for proactive deepfake mitigation via attention-driven watermarking and blockchain-based authenticity verification

Long-wave infrared narrowband multispectral filter based on the plasma decoupling mechanism

Metal plasmonic filters enable compact multispectral sensing, yet conventional designs are constrained by Ohmic losses. In this work, we designed and fabricated a narrowband long-wave infrared spectral filter based on perforated Au films and nanorings, achieving high-resolution multispectral filtering in the 7.5–14 μm range with a FWHM of only 0.26 μm, approximately one-fifth that of conventional plasmonic filters. Fabrication was accomplished using i-line stepper lithography for large-area patterning, while the self-deposition effect during ion-beam etching was ingeniously leveraged to achieve cost-effective nanoring fabrication. The transmission bandwidth of the fabricated filter was characterized using Fourier-transform infrared spectroscopy, demonstrating excellent agreement between experimental and simulation results. This work holds promise for addressing the long-standing resolution limitations of plasmonic filters.

Coordinate transformation method for beam grazing angle calculation of space-based early warning radar

Abstract With the rapid development of space technology and the increasing demand for global security early warning, space-based early warning Radar (SBR) is playing an increasingly important role in defending against potential threats. Based on the perturbed motion model of low-earth orbit satellites, this paper proposes a method for calculating the beam grazing angle of SBR using coordinate transformation techniques. The method is characterized by its clear process and simple calculation. The effectiveness of this method has been verified through simulation experiments, providing a practical method for the real-time calculation of the beam grazing angle of SBR.

Revealing trace water effect on the structural and optical evolutions of blue CsPbBr3 perovskite quantum dots

Quantum confined blue CsPbBr3 perovskite quantum dots (PeQDs) demonstrate superior spectral stability and easy tunability by particle size relative to their mixed halide counterparts. However, their practical application is hampered by their susceptibility to moisture-induced degradation. Herein, the structural and optical evolutions of blue CsPbBr3 PeQDs induced by trace water are systematically studied and their mechanism is elucidated. Experimental results show that trace water (H2O) induces red shift of spectra from blue to green, accompanying significant increase in photoluminescent quantum yield and one order lower non-radiative recombination rate. Furthermore, the H2O-treated PeQDs' size presents obvious increase from 6.3 to 8.0 nm without obvious change in crystalline pattern. By combining experimental characterizations, first-principles calculations, and verification experiments, we demonstrate that appropriate H2O exposure is responsible for substituting oleic acid ligand on PeQDs, resulting in particle growth and spectral red shift. Our work establishes that water attacks PeQDs via acid–base chemistry at surface ligand sites—a mechanistic insight critical for enhancing moisture stability in blue CsPbBr3 PeQDs.

Optimized flood scene segmentation with swin transformer-based architecture