Browse Articles

Retraction: [Pt(O,O’-acac)(γ-acac)(DMS)] Alters SH-SY5Y Cell Migration and Invasion by the Inhibition of Na+/H+ Exchanger Isoform 1 Occurring through a PKC-ε/ERK/mTOR Pathway

Broadband C  <b>+</b>  L-band waveguide amplifier enabled by co-doping with dual-size PbS/CdS quantum dots

In this work, we propose and demonstrate a broadband waveguide amplifier based on dual-size core–shell PbS/CdS quantum dot (QD) co-doping. PbS/CdS QDs with emission peaks at 1508 and 1604 nm, respectively, were dispersed in SU-8 photoresist at a 1:1 mass ratio to serve as the core material. We fabricated the devices using photobleaching combined with precision UV lithography and systematically characterized the propagation loss and gain performance of single-size and dual-size QD-doped waveguide amplifiers. The results verify that the dual-size co-doping strategy effectively extends the gain bandwidth. The co-doped waveguide amplifier covers a gain spectrum of 1450–1630 nm, with a full width at half maximum spanning 1490–1630 nm, fully covering the C + L-band, which achieves a maximum gain of 11.9 dB at 1540 nm. Within the entire C + L-band, gain fluctuation is kept below 3 dB, and the gain remains over 9 dB across all operating wavelengths. This work provides an effective route to realize broadband on-chip optical amplifiers.

The incidence and risk factors of sepsis following ovarian cancer surgery: A retrospective Nationwide Inpatient Sample database study

Background Postoperative sepsis is a significant complication following ovarian cancer surgery. However, limited studies have explored the risk factors associated with postoperative sepsis following ovarian cancer surgery in this context. This study aimed to assess the prevalence of postoperative sepsis and identify its associated risk factors. Methods This study retrospectively analyzed data from patients who underwent ovarian cancer surgery between January 2010 and December 2019 using the Nationwide Inpatient Sample (NIS) database. The age range of the study population is between 18 and 99 years old. Patients were categorized into two groups based on the presence or absence of postoperative sepsis. Data on patient demographics (e.g., race, age), hospital characteristics (e.g., insurance type, bed size, teaching status, region), preoperative comorbidities, and postoperative complications were extracted for comparison. Univariate and multivariable logistic regression analysis were conducted to identify factors associated with postoperative sepsis. Results A total of 39,049 patients were identified in the NIS database. Among them, 1,288 cases of postoperative sepsis were observed, representing an incidence rate of 3.3%. Patients with postoperative sepsis exhibited higher hospital charges, advanced age, prolonged length of stay (LOS), and increased in-hospital mortality. Preoperative risk factors for postoperative sepsis included congestive heart failure, coagulopathy, metastatic cancer, etc. Postoperative sepsis was associated with major complications, including electrolyte imbalance, urinary tract infection, thrombocytopenia, etc. Conclusions The incidence of postoperative sepsis following ovarian cancer surgery has shown a slight increase over time. Postoperative sepsis is associated with advanced age, race, prolonged LOS, higher hospital charges, in-hospital mortality, preoperative comorbidities, and perioperative complications. Recognizing these risk factors is essential for improving patient prognosis.

High dynamic range lensless on-chip microscopy via an overexposure inverse-projection operator

Lensless on-chip microscopy (LoM) enables high-throughput, label-free imaging with a compact setup and high numerical aperture. Its performance is limited by sensor saturation, which distorts high-intensity measurements and degrades reconstruction of the complex field. We report a high-dynamic-range inverse-projection reconstruction (HDR-IPR) framework that models saturation via an overexposure operator and jointly reconstructs the complex object field without multiple acquisitions at each predefined exposure duration. Using an approximate inverse-projection operator and alternating direction projection with complex total variation regularization, HDR-IPR effectively restores saturated signals while suppressing noise. Experiments demonstrate superior reconstruction quality, cleaner backgrounds, and enhanced reconstruction of fine structural details, providing a practical solution for HDR lensless imaging with standard sensors.

Engineering of T7 DNA-dependent RNA polymerase with activity at elevated temperature

Bacteriophage T7 RNA polymerase (T7 RNAP) is a key enzyme for in vitro transcription (IVT) and plays a central role in the production of synthetic mRNA for research and therapeutic applications. However, IVT frequently generates double-stranded RNA (dsRNA) as an undesired by-product, which can trigger innate immune responses and compromise mRNA quality. Increasing reaction temperatures reduces dsRNA formation, however, the wild-type T7 RNA polymerase exhibits limited stability under such conditions. Therefore, polymerase variants with enhanced thermotolerance enable more robust transcription at elevated temperatures while minimizing dsRNA generation. To address this limitation, we aimed at obtaining T7 RNA polymerase variants with increased thermotolerance using the Protein Repair One Stop Shop (PROSS) web server. Four crystal structures of T7 RNA polymerase, comprising a promoter complex, an initiation complex, and two elongation complexes were used as input for independent PROSS runs. Mutations shared across all four designs for each PROSS index were then combined to generate multi-structure PROSS Combined Designs (PCDs). In the subset evaluated experimentally, PCD9 retained full-length transcription activity at temperatures up to 48 °C, whereas wild-type T7 RNA polymerase showed strong loss of activity under the same buffer conditions. At 48 °C, PCD9 supported the synthesis of kilobase-length scale transcripts and produced no detectable dsRNA signal in a dot blot assay. In contrast, the wild-type enzyme generated strong dsRNA signals at 37 °C and failed to produce detectable RNA at 48 °C. Additional PROSS variants derived exclusively from the elongation complex structure were inactive at both 37 °C and 48 °C. Together, these results show that multi-structure PROSS design can yield a thermotolerant T7 RNA polymerase with improved performance at elevated temperature and reduced dsRNA byproduct formation. The findings also suggest that restricting stability design to a single structural state may not fully capture the requirements of a highly dynamic enzyme.

Repairing etched sidewall surface of InGaN/GaN micro-light emitting diode through neutral N/H radicals in high vacuums

Sidewall defects induced in the etching process critically limit the development of high-performance, small-size gallium nitride-based light emitting diodes (LEDs). Although conventional post-etch techniques like wet chemical etching have been applied to modify the etched surface, problems such as impurity re-absorptions and modification on sidewall morphology still stand. In this work, we report a novel sidewall repair technique using a radio frequency atom source to restore sidewall defects. Treatment of neutral reactive N/H species effectively mitigates the surface Fermi level pinning and reduces the defect-related surface states. This step is directly followed by vacuum-interconnected atomic layer deposition passivation, preventing air exposure and secondary impurity adsorption. Based on this strategy, the effect of N/H treatment is more pronounced in smaller devices. For 5-μm devices, the electroluminescence intensity at a current density of 10 A/cm2 increases by approximately 34%, the peak external quantum efficiency improves by 35%, and the reverse leakage current density at −5 V is reduced from 1.30 to 9.64 × 10−6 A/cm2. This strategy provides an effective methodology aiming for sidewall repair of micro-LEDs.

Imine Linkage Isomerism in Layer‐Entangled Three‐Dimensional Covalent Organic Frameworks Modulates Fluorescent Sensing

ABSTRACT Three‐dimensional covalent organic frameworks (3D COFs) constructed from entangled two‐dimensional layers represent a rare yet intriguing structural class; however, the influence of variations in linkage structure within such architectures remains unexplored. Herein, we investigate a linkage‐isomeric pair of isoreticular layer‐entangled 3D COFs with opposite imine bond orientations (3D‐An‐CN‐COF and 3D‐An‐NC‐COF). Remarkably, although these two frameworks share nearly identical composition, topology, and porosity, the subtle difference in C═N bond orientation leads to pronounced differences in their optoelectronic properties and fluorescent sensing behaviors. In particular, 3D‐An‐CN‐COF exhibits nearly an order‐of‐magnitude higher sensitivity toward 2,4,6‐trinitrophenol (TNP) in aqueous media than 3D‐An‐NC‐COF, with a quenching constant of 3.27 × 10 6  M −1 and a detection limit of 9.5 nmol L −1 , placing it among the most sensitive COF‐based fluorescent sensors for TNP reported to date. These results establish imine linkage isomerism as an effective structural parameter for reprogramming the optoelectronic properties and sensing behavior of layer‐entangled 3D COFs, offering new insight into the rational design of high‐performance fluorescent sensing materials.

Terahertz quantum-cascade vertical-external-cavity surface-emitting laser with high-contrast grating output coupler

We report a twofold increase in slope efficiency of a terahertz quantum-cascade vertical-external-cavity surface-emitting laser enabled by an all-dielectric high-contrast grating output coupler (OC). In contrast to a conventional metal-mesh OC on a quartz substrate, the dielectric grating eliminates losses associated with the metal. The device operates in pulsed and continuous-wave modes, with threshold current and maximum operating temperature comparable to those of the quartz-based OC. A circular beam pattern is maintained across the full tuning bandwidth.

Optical study of the two-dimensional electron gas and the total electronic polarization discontinuity in Sc <i>x</i> Al1− <i>x</i> N/GaN heterostructures

Wurtzite ScxAl1−xN/GaN heterostructures are predicted to exhibit large polarization discontinuities at the interface, leading to the formation of two-dimensional electron gases with high sheet carrier concentrations. However, the magnitude of these polarization discontinuities is currently under extensive discussion. To address this, three samples with Sc contents of 4%, 13%, and 18% are investigated, providing experimental insight into the evolution of the polarization discontinuity. Broad luminescence, originating from the En=2 level in the triangular quantum well at the heterostructure interface, is observed. By extracting the energetic position of the luminescence and combining the analysis with band structure simulations, experimental values for the polarization discontinuities of the ScAlN/GaN heterostructures are determined. For the samples containing 4%, 13%, and 18% Sc, the corresponding values are 0.113±0.009, 0.071±0.014, and (0.072±0.013)Cm−2, respectively. These findings agree with theoretical expectations, as lattice-matched ScAlN on GaN at ≈13 % Sc exhibits nearly zero piezoelectric polarization, whereas at 4% and 18% Sc, the piezoelectric polarization has opposite signs, reflecting the different strain states of the epilayer. The absorption edge energies for the samples are found to be 5.95, 5.87, and 5.78 eV for 4%, 13%, and 18% Sc, respectively.

Post‐Translational Isoaspartate Promotes Amyloid Formation in β ₂ ‐Microglobulin

ABSTRACT β 2 ‐Microglobulin (β2m) aggregation is central to dialysis‐related amyloidosis (DRA), yet the molecular triggers underlying its fibrillogenesis remain incompletely defined. Among proposed mechanisms, isoaspartate (isoAsp) formation at Asn residues has been implicated but never directly tested due to synthetic inaccessibility. Here, we report the total chemical synthesis of β2m variants containing isoAsp at known in vivo hotspots, Asn 17 and Asn 42 , enabling precise structural and functional interrogation. Remarkably, the isoAsp 17 ‐modified β2m exhibited greater fibril formation capacity than the pathogenic ΔN6‐β2m variant, suggesting a previously underappreciated contribution of isoAsp 17 . Structural characterization was complemented by spectroscopic and TEM analyses, which demonstrated that isoAsp 17 promotes fibril formation. Our findings provide the first direct experimental evidence that a spontaneous post‐translational modification can initiate amyloidogenesis in β2m, redefining the molecular basis of DRA and highlighting isoAsp as a general driver of pathological protein aggregation.

High-performance WSe2 Geiger avalanche photodetector from 405 to 808 nm

Avalanche photodiodes are attractive for weak-light detection. However, conventional avalanche devices usually suffer from high breakdown voltage, large dark current, and a limited gain–noise trade-off, restricting their applications in low-power and ultrasensitive photodetection. Here, we report a Pt/WSe2/graphene asymmetric Schottky diode that exhibits bilateral Geiger-mode avalanche operation. It shows abrupt avalanche breakdown under both positive and negative biases, with room-temperature breakdown voltages of approximately +19.6 and −23.45 V, respectively. Owing to the asymmetric Schottky barriers and bias-induced band bending in ambipolar WSe2, the carrier injection terminal and high-field multiplication region can be switched by the bias polarity, enabling bilateral impact ionization in a two-terminal geometry. Temperature-dependent investigations from 100 to 300 K confirm stable bilateral avalanche operation, with the breakdown voltage increasing at lower temperatures due to the modulation of carrier acceleration and scattering. Under femtowatt-level illumination at room temperature, photogenerated carriers facilitate impact ionization and shift the avalanche threshold toward lower bias. The device exhibits avalanche gains of 1.11 × 105 and 1.25 × 104 under negative and positive bias, respectively, and enables weak-light detection over 405–808 nm. At 808 nm, the responsivity reaches 107 A W−1 and the specific detectivity reaches 1014 Jones. This work demonstrates that asymmetric Schottky-contact engineering combined with ambipolar WSe2 transport provides an effective strategy for high-gain, high-detectivity, and bidirectional two-dimensional avalanche photodetectors.

Optically stimulated spin dynamics in a multi-domain CoO/Pt bilayer

The magneto-optical birefringence (MOB) effect has been used to explore the ultrafast spin dynamics of a MgO(001)/CoO(8 nm)/Pt(2 nm)/Al2O3(3 nm) structure using optical pump–probe measurements. Energy is transferred to the CoO layer after the pump pulse is partially absorbed within the Pt layer. The MOB is found to affect either the transient rotation or the transient reflectivity response, according to the alignment of the plane of incidence of the probe beam relative to the crystallographic axes of the epitaxial CoO layer. The amplitude and polarity of these transients are correlated with the antiferromagnetic domain structure, and the antiferromagnetic order is observed to relax on timescales of 2–10 ps. A non-linear dependence of the rotation amplitude on the pump laser fluence is consistent with full quenching of antiferromagnetic order beyond a fluence of ∼1 mJ/cm2, while larger fluences lead to a reduced relaxation time, increased heat accumulation, and irreversible domain modification.

A ¹⁹ F MRI/NIR‐FL Nanoprobe for “Turn‐On” Imaging of β‐Secretase (BACE1) Activity in Alzheimer's Disease

ABSTRACT Alzheimer's disease (AD) is the most common progressive neurodegenerative disorder with very few therapeutic methods; thus, its early detection is urgently important. β‐secretase (BACE1) is a well‐recognized biomarker of early‐stage AD, but its in vivo imaging‐based diagnostic method is rarely reported. Herein, we report a BACE1‐disassemblable nanoprobe, 19 F‐Cy5.5‐NP for “Turn‐On” 19 F magnetic resonance/near‐infrared fluorescence ( 19 F MR/NIR‐FL) imaging of the enzyme activity in AD in vivo. The “Turn‐On” 19 F MRI signals are employed for imaging BACE1 activity with high specificity, while the “Turn‐On” NIR‐FL signals are used for double checking the enzyme activity with high spatial resolution. Specifically, 19 F‐Cy5.5‐NP, with a silent 19 F MR/NIR‐FL signal is obtained from the precursor Cys(StBu)‐Glu‐Val‐Asn‐Leu‐Asp‐Ala‐Glu‐Phe(CF 3 )‐Lys(Cy5.5)‐CBT ( 19 F‐Cy5.5 ) through a CBT‐Cys click reaction. Upon BACE1 cleavage, the nanoprobe disassembles, resulting in 6.8 ± 1.3‐fold and 9.5 ± 0.3‐fold increases of 1 9 F NMR and NIR‐FL signals in vitro, respectively. Moreover, 19 F‐Cy5.5‐NP renders 4.6 ± 0.9‐fold/1.5 ± 0.1‐fold higher 19 F MRI/NIR‐FL signal in Aβ 25–35 ‐treated PC12 cells than that in normal PC12 cells. In vivo experimental results show that this nanoprobe enables the precise imaging of BACE1 activity in AD zebrafish models. We anticipate that 19 F‐Cy5.5‐NP could be applied for the early diagnosis of AD in clinics in the future.

Diamond current sensor integrated with a magnetic flux concentrator

Low-frequency weak-current measurements are essential for applications such as nanoscale electronic characterization, biological ionic-current sensing, and battery leakage monitoring. While magnetometry with nitrogen-vacancy (NV) centers in diamond has been widely applied to high-current sensing, its use for ultra-weak-current detection remains relatively unexplored. Here, we demonstrate a room-temperature current sensor by integrating an NV-diamond magnetometry with a ring-shaped magnetic flux concentrator. Owing to the high permeability of the magnetic material and geometry-induced flux concentration, magnetic fields generated by ultra-weak currents are efficiently collected and enhanced at the sensor location. We achieve a current sensitivity of 0.39 nA/Hz, normalized to a single coil turn, and observe a linear transfer response with measurement deviations remaining below 3% across the tested current amplitudes and frequencies. These results provide a viable approach for extending NV-based sensing to low-frequency, ultra-weak-current regimes and offer a scalable platform for weak-signal detection in practical applications.

Investigation of hot electrons in polarization-graded AlGaN/GaN HEMTs

Hot electrons in polarization-graded AlGaN/GaN high electron mobility transistors (HEMTs) were investigated using electroluminescence (EL) spectroscopy and compared to reference conventional abrupt-interface HEMTs. The electron temperature Te was determined from EL over a range of bias voltages and ambient temperatures. Te was lower for the polarization-graded devices, with a Te saturation observed at drain voltage VDS&amp;gt;13 V. Hydrodynamic technology computer-aided design (TCAD) simulations, calibrated to experimental IV and Te data, show that a 24% reduction in the peak lateral electric field is the primary driver for the reduced Te in the polarization-graded HEMTs. Electric field and hot carrier effects are clearly reduced in polarization-graded devices, with potential implications for improved reliability and noise performance. A consistent hot electron relaxation time of 18 fs was determined for both device types, demonstrating further that EL-based measurements are a powerful tool for calibrating TCAD models and probing hot carriers in GaN transistors.

Hidden ordered compound-layer and its tailoring of the electronic/optical property in Ge2Sb2SexTe5−x alloys

Ge2Sb2SeₓTe5−ₓ (0 &amp;lt; x &amp;lt; 5, GSST) alloys represent an emerging class of phase-change materials for integrated photonics. However, the microscopic origins underlying their superior performance compared to the parent compound Ge2Sb2Te5 remain elusive. By using atomic simulations, this work elucidates that the thermal stability and low optical loss of GSST are fundamentally governed by the formation of an in-layer compound-like structure with SeTe2 or Se2Te stoichiometry depending on the Se content, contrasting with the previously believed pure-element-layered model where Se and Te atoms occupy separate layers inside GSST. The newly identified compound-layered structures maintaining stability at temperatures above 370 K yield an enlarged bandgap, weakened antibonding character, and more importantly, a moderate refractive index as well as a decreased extinction coefficient, which align better with the experiment compared to the previously believed model. The present findings not only help bridge the long-standing theory–experiment gap regarding the optical properties of GSST by redefining its atomic structure but also establish local chemical ordering as a critical materials design principle for high-performance photonics.

Field-free spintronic terahertz emitter with polarization tunability

With the rapid expansion of terahertz (THz) applications in next-generation communication systems, imaging technologies, and quantum manipulation, the realization of efficient and highly integrated THz sources that do not rely on complex auxiliary components has emerged as a key challenge. Although spintronic THz emitters have advanced considerably in recent years, most existing schemes still depend on external magnetic fields to stabilize the magnetization orientation, which constitutes a major structural constraint for practical device integration. In this work, we introduce exchange bias into spintronic THz emission by employing a ferromagnetic/antiferromagnetic FeNi/IrMn3 heterostructure, thereby enabling field-free operation of the emitter. Through interfacial exchange coupling, the magnetization of the FM layer is pinned in a well-defined direction, which ensures reliable spin-current injection and spin-to-charge conversion in the absence of an external magnetic field. As a result, robust THz emission can be achieved under zero-field conditions. Beyond eliminating the magnetic field requirement inherent to conventional spintronic THz sources, the incorporation of a stripe-patterned metasurface further allows efficient generation and controllable manipulation of broadband chiral THz waves. A field-free spintronic THz source with controllable polarization state and high efficiency has been achieved.

Advances in BODIPY Derivatives for Antibacterial Phototherapy

ABSTRACT The escalating threat posed by antibiotic‐resistant bacteria and biofilm‐associated infections has driven increasing interest in non‐antibiotic antibacterial strategies. Antibacterial phototherapy (PT), including photodynamic therapy (PDT) and photothermal therapy (PTT), has attracted considerable attention owing to its spatiotemporal controllability, broad‐spectrum antibacterial activity, and low propensity for inducing drug resistance. Boron‐dipyrromethene (BODIPY) dyes, featuring exceptional structural tunability and favorable photophysical properties, have emerged as versatile scaffolds for the construction of antibacterial phototherapeutic systems. Through molecular engineering strategies including cationization, heavy‐atom incorporation, and π‐conjugation extension, combined with nanoassembly approaches, both the excited‐state processes of BODIPY and its interactions with bacterial interfaces can be precisely regulated. Integration into diverse nanoplatforms further improves aqueous dispersibility, biological stability, and accumulation at bacterial or biofilm interfaces, thereby enhancing reactive oxygen species (ROS) generation or enabling photothermal effects to achieve PDT, PTT, or synergistic antibacterial therapy. This review systematically summarizes the design strategies and structure‐activity relationships of BODIPY‐based antibacterial phototherapy reported over the past five years, covering molecular engineering of small‐molecule photosensitizers and nanoplatforms, bacterial targeting and carrier design, and discussing the challenges and future perspectives associated with clinical translation, particularly in terms of biosafety and targeted delivery.

Gate-tunable superconducting tunneling spectra of Ti/LaAlO3/KTaO3 (111) planar junctions

The KTaO3 (111) interface has attracted considerable attention due to its distinctive superconducting properties, which differ substantially from those of SrTiO3-based interfaces. Despite extensive investigations, the pairing mechanism of Cooper pairs at these interfaces remains elusive. Tunneling spectroscopy offers direct access to the pairing mechanism at buried superconducting interfaces; however, it requires ultrathin barrier layers that disfavor the formation of two-dimensional electron gas and interfacial superconductivity. Here, we employ titanium as the top electrode, enabling reduction of the LaAlO3 barrier thickness to 1.8 nm while maintaining stable superconductivity. This configuration facilitates the fabrication of planar tunneling junctions exhibiting well-resolved tunneling spectra. Our measurements reveal that the tunneling spectra of the LaAlO3/KTaO3 (111) interface are consistent with a single s-wave gap with a coupling strength ratio 2Δ/kBTc ranging from 3.5 to 4.0, slightly exceeding the Bardeen–Cooper–Schrieffer weak-coupling limit. The superconducting gap remains approximately 0.3 meV, independent of LaAlO3 barrier thickness. Moreover, back-gating simultaneously modulates transport properties and tunneling spectra, revealing no pseudogap up to electric fields of 3.6 kV/cm, in contrast to LaAlO3/SrTiO3 interfaces. However, increasing the gate field to 6.0 kV/cm induces an irreversible superconductor-to-insulator transition, demonstrating the fragility of interface conductivity with thinner LaAlO3 capping layers. These findings illuminate the pairing symmetry of LaAlO3/KTaO3 interfaces and advance our understanding of KTaO3-based interface superconductivity.

Catalytic Enantioselective Intramolecular Aza‐Michael Addition to α,β‐Unsaturated Esters

ABSTRACT A bifunctional iminophosphorane (BIMP)‐catalyzed enantioselective intramolecular aza‐Michael reaction of sulfonamides to tethered α,β‐unsaturated esters is described. Reactivity toward traditionally challenging ester Michael acceptors is achieved through careful catalyst design, enabling the synthesis of enantioenriched pyrrolidines, piperidines, and indoline derivatives in excellent yields (up to 99%) and enantiomeric ratios (up to 97.5:2.5 er) under operationally simple conditions. The broad reaction scope demonstrates excellent tolerance to variation in the sulfonamide group, the Michael acceptor, and substituents on the tether in between. Furthermore, the synthetic utility of the method is highlighted by gram‐scale reactions at reduced catalyst loadings and by downstream derivatization of multiple enantiopure products.