Browse Articles
Discover research articles across all indexed journals
Self-organized metasurface enabling negative photoconductance and memristive behavior via van der Waals interaction
Negative photoconductance (NPC) and memristive behavior have been observed simultaneously in planar, metal-oxide-based heterojunctions. Self-organized TiO2 crystalline metasurface thin films were prepared by spin coating with polymer-templated precursors, yielding a smooth, uniform, and full-coverage surface with metastructure features sizing from 1 to 3 μm. After depositing CuO crystalline thin films on a conductive substrate, two metal-oxide thin films are held together face-to-face by mechanical clips to form a heterojunction diode. Due to stacking architecture, van der Waals interactions play a crucial role at the interface. The IV characteristics of the pn heterojunctions exhibit pronounced rectification and NPC, with the current dropping by a factor of 6 as the temperature increases by 20 °C under white-light irradiation. The NPC can be attributed to increased charge-carrier recombination and lattice vibrations induced by infrared light absorption, leading to a temperature rise. The cyclic IV curves exhibit a narrow hysteresis, a characteristic of a memory-type resistor during voltage sweeping. The mechanism underlying memristive traits has been qualitatively hypothesized using a circuit model based on series and parallel connections of resistors and capacitors, reflecting the metastructure at the interface. The fabricated memdiodes may serve as alternative electronic elements for integration into photo-memory-type computing hardware.
Turn-on luminescence from molecular rotor realignment in metal-organic framework thin films
Abstract Sub-unit motion within metal-organic frameworks (MOFs) offers unique opportunities for nanoscale sensing. However, achieving controlled partial rotation of bulky linkers remains a significant challenge. In this study, a 50-fold luminescence enhancement is observed from a MOF thin film when intra-pore solvent flow orients the linker chromophores. These MOF thin films can be prepared via a facile drop-casting method on various substrates. The MOFs structure consists of zinc-coordinated layers containing rotatable chromophores, separated by pillar molecules. Grazing-incidence wide-angle X-ray scattering analysis confirms the formation of highly oriented films. The deposition of a volatile organic compound, such as ethanol, triggers a significant enhancement in luminescence as the solvent nears complete evaporation. Photophysical characterization and quartz crystal microbalance measurements reveal that this phenomenon is driven by internal stress on the MOF’s pore level generated during the final stages of evaporation. This stress can result in a realignment of the MOF chromophores at the molecular scale. Consequently, this dynamic turn-on luminescence behavior establishes a foundation for nanoscale platforms capable of indicating solvent volatilization in real time.
Investigation of dynamic evolution and emission pattern transition in an atmospheric pressure surface micro-discharge
This study investigates the dynamic evolution and emission pattern transition of atmospheric-pressure helium surface micro-discharges using optical emission spectroscopy and electrical measurements. Utilizing an asymmetric electrode configuration, multiple short-duration microdischarges are observed during the negative half-cycle, while the positive half-cycle is dominated by a single high-current streamer discharge that determines the overall emission profile. With increasing applied voltage, a periodic transition between symmetric and asymmetric discharge patterns occurs, accompanied by a non-monotonic variation in peak discharge current. This behavior is attributed to the memory effect of surface charges and the influence of the applied electric field. The transition process unfolds in three distinct stages: an initial symmetric discharge pattern with increasing current, sustained by a uniform distribution of surface charges aligned with the electric field; a transitional phase where symmetric and asymmetric patterns coexist while the current declines, reflecting a reorganization of surface charges; and a stabilized asymmetric pattern with recovering current, driven by a localized, non-uniform surface charge field. Moreover, plasma propagates asynchronously across a hexagonal mesh electrode array. Ignition starts within individual mesh units and spreads progressively to neighboring units at an estimated velocity of about 2.25 × 104 m/s. During the positive half-cycle, the propagation direction reverses compared to the last discharge event of the previous negative half-cycle, due to the electric field polarity reversal and the residual surface charge distribution. These findings provide valuable insights for the design and optimization of surface micro-discharge devices in biomedical applications.
Routine blood tests and machine learning identify complications in high myopia
Cut-enabled anisotropic and non-reciprocal elasticity in chiral metamaterials
We introduce strategically placed cuts into chiral mechanical metamaterials to achieve strongly anisotropic and static non-reciprocal elasticity in a fully passive architecture. Under loading, the cuts switch between open states that preserve auxetic kinematics and closed contact states that trigger an abrupt stiffness increase, thereby breaking symmetry. By systematically varying the cut topology—the number, placement, and orientation of cuts—we identify regimes with sharp stiffness transitions and pronounced uniaxial and orthogonal non-reciprocity. A topological coding strategy is proposed to program these responses at the unit-cell level. These results establish cut-mediated opening and contact as a general mechanism for designing non-reciprocal mechanical metamaterials.
AcrIIA7 hijacks tracrRNA to block CRISPR-Cas system
Electronic thermal conductivity of doped Rashba–Floquet <i>d</i> -wave altermagnets
Altermagnets, a novel class of collinear magnets with momentum-dependent spin splitting and zero net magnetization, offer unique opportunities for tunable thermal transport. Here, we investigate the electronic thermal conductivity (ETC) in two-dimensional d-wave altermagnets, focusing on its anisotropy and responsiveness to external perturbations, such as electrostatic gating, circularly polarized light driving, and doping. Employing a semiclassical Boltzmann transport framework with relaxation-time approximation, we derive expressions for the ETC tensor integrated over the Floquet-renormalized quasiparticle spectrum. Our model incorporates Rashba spin–orbit coupling from perpendicular gating and Floquet engineering via high-frequency optical driving, which collectively modify the band structure, spin textures, and carrier velocities. Numerical evaluations reveal pronounced directional anisotropy in the ETC along principal crystallographic axes, with gating enhancing in-plane distortions and light driving enabling dynamic renormalization of the altermagnetic gap and Rashba parameters. These effects yield temperature-dependent thermal responses that deviate from the pristine phase of matter, positioning altermagnets as versatile platforms for thermospintronic devices and heat management without net magnetization.
Mid-infrared to ultraviolet efficient multiphoton frequency upconversion in NbOI2 crystals
Impact of carrier injector design on the threshold of interband cascade lasers
We theoretically investigate how the injector region design of interband cascade lasers (ICLs) impacts the threshold carrier and current densities. The model combines a polarization-sensitive 8-band k⋅p calculation, electrostatics, and a microscopic calculation of Auger recombination rates. The inelastic carrier–carrier scattering is included at the lowest order using quasi-equilibrium Green’s functions. Our approach captures the combined effects of charge-carrier redistribution, parasitic absorption, and bias voltage on the Auger recombination rate. We show that heavily doping the electron injector suppresses the dominant multi-hole Auger recombination by reducing the hole population of the recombination quantum wells. This agrees with the experimental observation that the heavy doping reduces threshold currents. Unlike the measurements, however, they do not increase at high doping concentrations in our model, which does not include scattering-mediated carrier escape and/or light absorption. Furthermore, by introducing indium to the conventional GaSb hole injector wells, we explain the rule of thumb from experiments that raising the hole injector levels does not outperform the doping strategy. Our model provides physical insights for optimizing ICL carrier injectors.
EPInformer: scalable and integrative prediction of gene expression from promoter-enhancer sequences with multimodal epigenomic profiles
Geometry-induced sensitivity enhancement in unconventional nano-SQUID architectures
Superconducting Quantum Interference Devices (SQUIDs) represent a cornerstone of nanoscale metrology, offering unparalleled magnetic field sensitivity across diverse scientific and technological frontiers. Since device performance is intrinsically linked to loop geometry and architecture, we employ the Ginzburg–Landau formalism to investigate the electrodynamics of an unconventional nano-SQUID integrated with a pickup loop. This study rigorously evaluates the impact of geometric scaling, focusing on the effects of minimized loop dimensions and track widths on flux noise and sensitivity. Our findings demonstrate that optimizing the device’s tilt angle and spatial configuration significantly enhances magnetic coupling and detection limits. These results provide a theoretical framework for engineering next-generation nano-SQUIDs with superior resolution for localized magnetic sensing.
Dopamine and serotonin inversely modulate D2 medium spiny neurons to regulate cocaine reward
Role of structural asymmetry in tailoring electromagnetically induced transparency and figure of merit in terahertz metamaterials
Electromagnetically induced transparency (EIT) in metamaterials, a classical analog of quantum EIT, exhibits a sharp transparency window with steep dispersion, enabling applications such as sensing and slow-light devices. Although EIT has been widely demonstrated, systematic investigations into tuning and optimizing the response through structural parameters remain limited. In this work, we present a terahertz metamaterial composed of a double split-ring resonator unit cell, where EIT is tuned by varying the structural asymmetry (α). We evaluate the figure of merit of EIT using two approaches. The first approach considers the product of the quality factor and transmission intensity, while the second is based on the product of the group delay and transmission intensity. Both methods identify intermediate values of α as optimal for achieving a strong and spectrally selective EIT response. This study demonstrates the effectiveness of structural asymmetry in tuning the EIT characteristics and provides insights into the design of adaptable terahertz photonic devices.
Optimizing global genomic surveillance for early detection of emerging SARS-CoV-2 variants
Voltage controlled magnetic anisotropy at iron/spinel oxide interfaces
The ability to use an applied voltage to effectively manipulate perpendicular magnetic anisotropy is critical for high density, robust magnetic random access memory devices. Using first principle simulations, we examine voltage control of perpendicular magnetic anisotropy at the interface between Fe and several different spinel oxides (MgAl2O4, MgGa2O4, and ZnAl2O4). These spinel oxides have an excellent lattice match with Fe and there is good alignment of spinel O atoms with Fe atoms at the interface. We find that all of these Fe|spinel oxide interfaces have high perpendicular magnetic anisotropy ranging from 1.87 to 1.89mJ/m2. The two Fe layers closest to the oxide interface provide significant contributions to the magnetic anisotropy. Calculations for Cu|Fe|spinel slabs under applied fields indicate VCMA coefficients in the range of (25–30 fJ V m) which are comparable to that found for Fe|MgO. Given the excellent lattice match with (001) bcc Fe for all of these spinel oxides and the demonstrated high TMR for the case of Fe|MgAl2O4, our results indicate that members of this spinel oxide family are promising candidates for tunneling barriers in future voltage controlled MRAM devices.
Experimental mechanician for plate lattice metamaterial discovery
Radiation tolerance of Ga2O3 for harsh environment applications: Neutron irradiation and defect studies
Gallium oxide (Ga2O3) has emerged as a promising material for high-power and radiation-tolerant electronics due to its ultra-wide bandgap and excellent thermal stability. In this study, single-crystal β-Ga2O3 was exposed to neutron irradiation for periods up to 300 h to investigate its structural, chemical, electronic, and mechanical response. Post-irradiation examination revealed that the material maintained its monoclinic crystal structure, with no evidence of phase transformation, elemental segregation, or significant bandgap alteration. Atom probe tomography and energy-dispersive spectroscopy confirmed uniform elemental distributions of Ga, O, and Fe, while high-resolution electron energy-loss spectroscopy indicated negligible changes in the electronic structure. Nanoindentation measurements showed an increase in hardness after irradiation, suggesting the formation of irradiation-induced defects and associated radiation-hardening. These findings demonstrate that β-Ga2O3 can withstand low-dose neutron irradiation while preserving its microstructural, chemical, and electronic integrity, highlighting its potential for robust, high-performance devices in extreme radiation environments.
Pyruvate metabolism enzyme Dlat induces mitochondria protein hyperacetylation to limit fatty acid oxidation in the HFpEF heart
Validity of one-dimensional evaporation model for confined microchannels
Evaporation lies at the heart of many industrial processes, ranging from power generation, thermal desalination, to advanced cooling systems. These technologies leverage the efficient mass and heat transfer that accompanies evaporation, making accurate evaluation of evaporative transport essential for optimal design. The kinetics of evaporative transport is governed by a thin non-equilibrium region near the liquid surface, known as the Knudsen layer. Within this layer, the flow deviates from the continuum, rendering computational fluid dynamics (CFD) inapplicable. To circumvent the complexity of multi-scale simulations, a one-dimensional (1D) evaporation model is conventionally employed to predict the flux from the Knudsen layer and applied to the CFD simulations as the boundary condition. This simplification minimally affects the overall mass flux when the system is much larger than the Knudsen layer. However, its accuracy becomes questionable in micro/nano devices. Here, we assess the accuracy of this approach by simulating evaporation into a microchannel using the direct simulation Monte Carlo method and comparing the results with CFD simulations coupled with the 1D model. Results confirm that the tangential velocity at the liquid surface has little impact on the accuracy of the 1D model, and that combining it with a reliable slip model allows effective prediction even under strong confinement. However, the presence of a large non-equilibrium pressure region may compromise predictions when the channel height is comparable to the mean free path. These findings provide guidance and define the applicability limits for the use of the 1D evaporation model in confined geometries.