Browse Articles

Anti‐Scattering Perovskite Scintillator Arrays for High‐Resolution Computed Tomography Imaging

Abstract Computed tomography (CT) imaging has emerge as an effective medical diagnostic technique due to its rapid and 3D imaging capabilities, often employing indirect imaging methods through scintillator materials. Arraying scintillators that can confine light scattering to enable high‐resolution CT imaging remains an area of ongoing exploration for emerging perovskite scintillators. Here an anti‐scattering cesium lead bromide (CsPbBr 3 ) scintillator array embedded within a polyurethane acrylate matrix for CT imaging using a cost‐effective solution‐processed method is reported. Due to the large refractive index contrast between the scintillator and matrix, photon propagation can be well confined within the CsPbBr 3 scintillator array to significantly suppress the light scattering and enhance the light collection efficiency by nearly two times compared to the monolithic film. Furthermore, the scintillator array exhibits low‐dosage and high‐resolution CT imaging capability by reconstructing a 3D tooth image with a good spatial resolution of 20.1 lp cm −1 at a low effective dose of 0.22 mSv. This work highlights that the CsPbBr 3 scintillator array is a highly promising candidate for CT imaging.

Assessment of the crystalline orientation of nanoscale semiconductor structures via atom probe tomography

We demonstrate the application of atom probe tomography for assessing the crystalline orientation of nanoscale semiconductor structures via the analysis of charge state ratio maps in the detector space. The experimental realization is carried out in the context of adventitious cone-shaped domains present in AlGaN quantum dot superlattices. The cone-shaped domains, which emerge from shallow pits generated in AlN and propagate through the superlattices, are shown to exhibit small misorientation angles of their crystalline 〈0001〉 poles. The results of the atom probe tomography analysis are confirmed by convergent beam electron diffraction measurements. The use of this methodology adds another layer to the application of this technique to semiconductor nanoscale systems, providing not only compositional maps but also information on the crystallographic orientation.

Optimized UNet framework with a joint loss function for underwater image enhancement

Polarization Boost and Ferroelectricity Down to One Unit Cell in Layered Carpy‐Galy La₂Ti₂O₇ Thin Films

AbstractLayered perovskite‐based compounds offer a range of unconventional properties enabled by their naturally anisotropic structure. Among these, the Carpy‐Galy phases (AnBnO3n+2), characterized by (110)‐oriented perovskite planes interleaved with additional oxygen layers, stand out for robust in‐plane polarization. However, the challenges associated with the synthesis of ultrathin Carpy‐Galy films and understanding the impact of strain on their properties limit their integration into devices. Here, La2Ti2O7 (n = 4) films grown on substrates imposing tensile, compressive, or negligible epitaxial strains are investigated. Surprisingly, a 3% tensile strain from DyScO3 (100) substrates facilitates layer‐by‐layer growth mode, whereas compressive (LaAlO3‐Sr2TaAlO6 (110)) or negligible (SrTiO3 (110)) epitaxial strains require post‐deposition annealing to reach comparable crystallinity. Using density‐functional theory calculations, scanning probe microscopy, X‐ray diffraction, scanning transmission electron microscopy, and polarization switching experiments, it is confirmed that these films possess exceptional ferroelectric properties, including a polarization of 18 µCcm−2 – more than three times higher than previously reported – as well as persistence of ferroelectricity down to a single‐unit‐cell thickness. This study not only advances the understanding of Carpy‐Galy phases as epitaxial thin films but also lays a foundation for their integration into advanced ferroelectric device architectures.

Electrocatalytic Biomass Oxidation via Acid‐Induced In Situ Surface Reconstruction of Multivalent State Coexistence in Metal Foams

Abstract Electrocatalytic biomass conversion offers a sustainable route for producing organic chemicals, with electrode design being critical to determining reaction rate and selectivity. Herein, a prediction‐synthesis‐validation approach is developed to obtain electrodes for precise biomass conversion, where the coexistence of multiple metal valence states leads to excellent electrocatalytic performance due to the activated redox cycle. This promising integrated foam electrode is developed via acid‐induced surface reconstruction to in situ generate highly active metal (oxy)hydroxide or oxide (MO x H y or MO x ) species on inert foam electrodes, facilitating the electrooxidation of 5‐hydroxymethylfurfural (5‐HMF) to 2,5‐furandicarboxylic acid (FDCA). Taking nickel foam electrode as an example, the resulting NiO x H y /Ni catalyst, featuring the coexistence of multivalent states of Ni, exhibits remarkable activity and stability with a FDCA yields over 95% and a Faradaic efficiency of 99%. In situ Raman spectroscopy and theoretical analysis reveal an Ni(OH) 2 /NiOOH‐mediated indirect pathway, with the chemical oxidation of 5‐HMF as the rate‐limiting step. Furthermore, this in situ surface reconstruction approach can be extended to various metal foams (Fe, Cu, FeNi, and NiMo), offering a mild, scalable, and cost‐effective method for preparing potent foam catalysts. This approach promotes a circular economy by enabling more efficient biomass conversion processes, providing a versatile and impactful tool in the field of sustainable catalysis.

The influence of contact resistance and interface layers in extraordinary magnetoresistance devices

The electrical resistance change of a device when subjected to applied magnetic fields is essential for magnetoresistive magnetometers as well as for studying fundamental transport phenomena in condensed matter. One of the largest magnetoresistances at room temperature is observed in extraordinary magnetoresistance (EMR) devices composed of high-mobility materials with metal inclusions. However, the contact resistance between the constituent materials is often detrimental to their performance. In this work, we study the influence of the interface-near region on the performance of EMR devices using a numerical model, which mimics local doping, carrier depletion, and mobility degradation by independently varying the carrier density and mobility of an interfacial layer. We show that the magnetoresistance decreases by five orders of magnitude when the specific contact resistance increases from 10−5 to 10−2Ω cm2. Our results also show that it is beneficial to increase the conductivity of the interface layer, even at the expense of degrading either its carrier density or mobility. This study paves the way for designing contacting strategies for realizing high-performing EMR devices.

Diagnostic behavior analysis of profuse data intrusions in cyber physical systems using adversarial learning techniques

Buffer‐Less Gallium Nitride High Electron Mobility Heterostructures on Silicon

Abstract Thick metamorphic buffers are considered indispensable for III‐V semiconductor heteroepitaxy on large lattice and thermal‐expansion mismatched silicon substrates. However, III‐nitride buffers in conventional GaN‐on‐Si high electron mobility transistors (HEMT) impose a substantial thermal resistance, deteriorating device efficiency and lifetime by throttling heat extraction. To circumvent this, a systematic methodology for the direct growth of GaN after the AlN nucleation layer on six‐inch silicon substrates is demonstrated using metal‐organic vapor phase epitaxy (MOVPE). Crucial growth‐stress modulation to prevent epilayer cracking is achieved even without buffers, and threading dislocation densities comparable to those in buffered structures are realized. The buffer‐less design yields a GaN‐to‐substrate thermal resistance of (11 ± 4) m 2  K GW −1 , an order of magnitude reduction over conventional GaN‐on‐Si and one of the lowest on any non‐native substrate. As‐grown AlGaN/AlN/GaN heterojunctions on this template show a high‐quality 2D electron gas (2DEG) whose room‐temperature Hall‐effect mobility exceeds 2000 cm 2  V −1  s −1 , rivaling the best‐reported values. As further validation, the low‐temperature magnetoresistance of this 2DEG shows clear Shubnikov‐de‐Haas oscillations, a quantum lifetime > 0.180 ps, and tell‐tale signatures of spin‐splitting. These results could establish a new platform for III‐nitrides, potentially enhancing the energy efficiency of power transistors and enabling fundamental investigations into electron dynamics in quasi‐2D wide‐bandgap systems.

Strong coupling between cavity and flopping-mode qubit beyond direct gate connection in a Si/SiGe triple quantum dot

Cavity coupled flopping-mode spin qubit is considered as a promising scheme for enabling long-range qubit interactions in large-scale semiconductor quantum computation. In this work, we fabricate a linear Si/SiGe triple quantum dot (TQD) array coupled with a high-impedance TiN coplanar waveguide cavity via the gate of outer quantum dot. By utilizing two adjacent dots within the TQD, we sequentially encode two flopping-mode qubits at different positions, whether with or without gate connection, which exhibit strong coupling to the cavity. Furthermore, we demonstrate the qubit manipulation with the help of dispersive readout, achieving Rabi oscillation frequencies of 16.9 and 13.7 MHz at zero detuning. These results expand the spatial range of qubit coupling and readout via the cavity, enhancing the operational efficiency of cavity-quantum dot array coupled system.

Direct current galvanic vestibular stimulation modulates sound localization abilities

Abstract The vestibular system has been shown to play a role in the integration of spatial sensory information. For instance, vestibular perturbations induce significant shifts in spatial tactile tasks, but results have been contradictory regarding auditory modality. This observation may be because some of the previous vestibular stimulation methods (i.e., stochastic GVS) did not reliably induce a self-motion effect. This study aims to evaluate the importance of directional illusory motion on auditory localization mechanism, using direct current GVS. Twenty young healthy participants performed a sound localization task under earphones with 9 positions in the azimuth plane divided into three quadrants 7Left (45°;− 30°;− 20°), Center (− 10°;0°;10°), and Right (20°;30°;45)]. Participants were asked to verbally identify the exact position of the sound source under 3 conditions: (1) Without GVS (2) GVS with anode on the right mastoid (3) GVS with anode on the left mastoid. Results were analyzed using the non-parametric Friedman test and Wilcoxon rank-sum post-hoc test with a Bonferroni correction applied to account for multiple comparisons. Compared to baseline, left anodal stimulation caused a greater error ratio for sounds in all quadrants. Moreover, for sounds in the right quadrant, a significantly greater error ratio was observed for anode left compared to the anode right condition. Right anodal condition caused a greater error ratio for sounds in the left and the center quadrants compared to the baseline condition. This study demonstrates for the first time, that sound source localization can be influenced by direct current GVS and is modulated according to the anode position.

Waveguide Microactuators Self‐Rolled Around an Optical Fiber Taper

Abstract Precisely capturing and manipulating microscale objects, such as individual cells and microorganisms, is fundamental to advancements in biomedical research and microrobotics. Photoactuators based on optical fibers serving as flexible, unobstructed waveguides are well‐suited for these operations, particularly in confined locations where free‐space illumination is impractical. However, integrating optical fibers with microscale actuators poses significant challenges due to size mismatch, resulting in slow responses inadequate for handling motile micro‐objects. This study designs microactuators based on hydrogel/Au bilayer heterostructures that self‐roll around a tapered optical fiber. This self‐rolling mechanism enables the use of thin hydrogel layers only a few micrometers thick, which rapidly absorb and release water molecules during a phase transition. The resulting microactuators exhibit low bending stiffness and extremely fast responses, achieving large bending angles exceeding 800° within 0.55 s. Using this technique, this study successfully captures rapidly swimming Chlamydomonas and Paramecium, and demonstrates programmable non‐reciprocal motion for effective non‐contact manipulation of yeast cells. This approach provides a versatile platform for microscale manipulations and holds promise for advanced biomedical applications.

Stabilizing Layered Oxide Cathodes Based on Universal Surface Residual Alkali Conversion Chemistry for Rechargeable Secondary Batteries

Abstract Layered transition metal oxides (LTMOs) are attractive cathode candidates for rechargeable secondary batteries because of their high theoretical capacity. Unfortunately, LTMOs suffer from severe capacity attenuation, voltage decay, and sluggish kinetics, resulting from irreversible lattice oxygen evolution and unstable cathode‐electrolyte interface. Besides, LTMOs accumulate surface residual alkali species, like hydroxides and carbonates, during synthesis, limiting their practical application. Herein, a universal strategy is suggested to in situ convert surface residual alkali into a stable polymer coating layer for LTMOs, thus turning wastes into treasure. The formation process of polymer coating involves NH 4 F treatment to consume residual alkali, then utilizing generated fluorides to induce the ring‐opening polymerization of tetrahydrofuran. Implementing this strategy to Li‐rich Mn‐based cathode materials (LRM) results in a notable reduction in voltage hysteresis, along with enhanced kinetics and cycling stability in lithium‐ion batteries. With this layer of encapsulation, surface lattice oxygen release and layered‐to‐spinel phase transition of LRM are significantly alleviated with minimal mechanical degradation and surface parasitic reactions. Such strategy can also be applied to air‐sensitive sodium‐rich LTMOs in sodium‐ion batteries, which showcases superior universality. This work might provide a promising solution to overcome residual alkali and interfacial instability issues for LTMOs in practical application.

Monitoring thermal evolutions of 2D layered semiconductor/polymer heterostructure with ultrafast photoacoustic spectroscopy

Utilizing 2D layered semiconductor as ultrafast photoacoustic transducer, we all-optically generate and track the propagation of picosecond acoustic pulses in 2D layered semiconductor/PMMA thin-film heterostructure via femtosecond laser pump-probe. By varying the environmental temperatures and the incident direction of pump laser pulse, the acoustic velocity of PMMA thin-film has been in situ monitored. The glass transition temperature of PMMA has been measured. Our work provides an all-optical means to noninvasively evaluate thermal responses of polymer thin-films, which are important for studies of thermal interface materials and thermal management of microelectronic devices.

Bioinformatic analysis of molecular expression patterns during the development and progression of metabolic dysfunction-associated steatotic liver disease (MASLD)

Plasmonic Single‐Molecule Affinity Detection at 10 ⁻²⁰ Molar

Abstract DNA can be readily amplified through replication, enabling the detection of a single‐target copy. A comparable performance for proteins in immunoassays has yet to be fully assessed. Surface‐plasmon‐resonance (SPR) serves as a probe capable of performing assays at concentrations typically around 10⁻⁹ molar. In this study, plasmonic single‐molecule assays for both proteins and DNA are demonstrated, achieving limits‐of‐detections (LODs) as low as 10⁻ 2 ⁰ molar (1 ± 1 molecule in 0.1 mL), even in human serum, in 1 h. This represents an improvement in typical SPR LODs by eleven orders‐of‐magnitude. The single‐molecule SPR assay is achieved with a millimeter‐wide surface functionalized with a physisorbed biolayer comprising trillions of recognition‐elements (antibodies or protein–probe complexes) which undergo an acidic or alkaline pH‐conditioning. Potentiometric and surface‐probing imaging experiments reveal the phenomenon underlying this extraordinary performance enhancement. The data suggest an unexplored amplification process within the biomaterial, where pH‐conditioning, driving the biolayer in a metastable state, induces a self‐propagating aggregation of partially misfolded proteins, following single‐affinity binding. This process triggers an electrostatic rearrangement, resulting in the displacement of a charge equivalent to 1.5e per 10 2 recognition elements. Such findings open new opportunities for reliable SPR‐based biosensing at the physical detection limits, with promising applications in point‐of‐care plasmonic systems.

Synchrotron 3D-RSM reveals the microstructure of superconducting YBa2Cu3O7−<i>x</i> films grown on various substrates

Further unleashing the full potential of YBa2Cu3O7−x (YBCO), a premier high-temperature superconductor, for devices in advanced communication technologies hinges on the refinement of its fabrication process. In this work, a synchrotron three-dimension reciprocal space mapping (3D-RSM) technique, which offers a larger Q-space range and higher spatial resolution, was developed and used to analyze YBCO films grown on (001)-oriented LAO, STO, and MgO substrates. The 3D-RSM results reveal that epitaxial YBCO c domains dominate the films, with minor YBCO a domains in YBCO/LAO. The YBCO c domains present a consistent epitaxial relationship with the substrate STO and LAO, with the domain boundary parallel to the substrate [110] or [1¯10] axes. In contrast, YBCO/MgO films exhibit two distinct in-plane epitaxy orientations. Quantitatively measured lattice constants indicate the possible Tc-related oxygen vacancy condition therein. A 2-in. YBCO/MgO film, prepared by a homemade pulsed laser deposition system, verified the structural non-uniformity issues, suggesting room for further optimization. This study underscores the advantages of synchrotron-based 3D-RSM for microstructure analysis, which could support process improvement and performance optimization in high-frequency applications.

Impact of snowfall on emergency medical system and mortality in patients with acute coronary syndrome

Mo-doped Ni/NiO supported on oxygen-deficient NiMoO4 with carbon derived from tannic acid for hydrogen evolution and hydrogen oxidation

The widespread deployment of anion exchange membrane unitized reversible fuel cells is contingent upon the development of stable and efficient non-precious metal electrocatalysts for the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER). This study reports on the synthesis of Mo-doped Ni/NiO hetero-nanoparticles supported on oxygen-deficient NiMoO4 (NiMoOX), with tannic acid (TA) integrated as both a carbon source and stabilizing agent (Ni/NiO-Mo/C@NiMoOX). In situ Raman spectroscopy elucidates the mechanism through which TA enhances the electrocatalytic activity. The resultant catalyst demonstrates superior HOR/HER performance, featuring a current density of 2.5 mA cm−2 at 100 mV overpotential for HOR, remaining stable for 24 h, and in HER, exhibiting a remarkably low overpotential of just −12 mV at a current density of −10 mA cm−2, with stability persisting for over 300 h, outperforming the commercial Pt/C catalyst.

The phase transition characteristics of n-pentane in silica slits with different wettability by Monte Carlo method

Spin State Modulation with Oxygen Vacancy Orientates C/N Intermediates for Urea Electrosynthesis of Ultrahigh Efficiency

Abstract The co‐electrolysis of CO 2 and NO 3 − to synthesize urea has become an effective pathway to alternate the conventional Bosch‐Meiser process, while the complexity of C‐/N‐containing intermediates for C−N coupling results in the urea electrosynthesis of unsatisfactory efficiency. In this work, an electronic spin state modulation maneuver with oxygen vacancies (Ov) is unveiled to effectively meliorate the oriented generation of key intermediates * NH 2 and * CO for C−N coupling, furnishing urea in ultrahigh yield of 2175.47 µg mg −1  h −1 and Faraday efficiency of 70.1%. Mechanistic studies expound that Ov can induce the conversion of the high‐spin state Ni 2+ (t 2g 6 e g 2 ) of Ni@CeO 2−x to the low‐spin state Ni 3+ (t 2g 6 e g 1 ), which markedly enhances the hybridization degree of the Ni 3d and the N 2p orbitals of * NO, facilitating the selective formation of * NH 2 . Notably, the in situ generated * NH 2 intermediates can serve as a localized proton donor to promote the electroreduction of CO 2 on the adjacent site Ce 3+ −O to exclusively afford * CO, followed by C−N coupling of each other to efficiently synthesize urea. The strategy of tailored switching of the active site spin state provides a reliable reference to rectify the electronic structure of electrocatalysts for directional CO 2 valorization.