Browse Articles

Anisotropic cation migration and strain driving compositional segregation in FACsPbI3

Formamidinium-cesium lead iodide (FACsPbI3) is among the most promising absorber materials for high-efficiency perovskite solar cells, and A-site cation mixing of FA and Cs represents a crucial strategy to enhance the long-term stability of devices. However, inhomogeneous spatial distribution of A-site cations can adversely impact photovoltaic performance. In this work, we employ density functional theory to investigate the influence of cation mixing on migration behavior and to elucidate the origin of compositional inhomogeneity. We find that the incorporation of Cs not only suppresses halide anion migration but also significantly inhibits the migration of both FA and Cs cations, with a particularly pronounced hindering effect on Cs migration under strain-free conditions. The spherical Cs ion exhibits anisotropic migration within the hybrid perovskite lattice, preferentially moving along the C-H axis of neighboring FA cation. In contrast, planar FA cations tend to migrate along pathways perpendicular to their own plane due to hydrogen-bond interactions, exhibiting behavior characteristic of a coupled rotational–translational motion. During the initial solidification stage of the hybrid perovskites, thermodynamically favorable Cs-aggregated domains readily form; subsequent lattice strain drives anisotropic migration of both Cs and FA, leading to spatially inhomogeneous cation distributions. These findings deepen the understanding of cation migration mechanisms in mixed-cation perovskites and reveal key factors responsible for compositional inhomogeneity, offering theoretical guidance for experimental strategies aimed at mitigating phase segregation in perovskites.

Equilibrium kink-like torsion deformation of a magnetoactive elastomer under a magnetic field

A novel effect involving the formation of a stable kink-like torsion deformation in a magnetoactive elastomer (MAE) beam subjected to a uniform magnetic field is theoretically predicted and experimentally confirmed. The phenomenon was demonstrated using an elastomer beam containing soft magnetic carbonyl iron microparticles within a silicone matrix. The torsion kink acts as a transition boundary between two undeformed homogeneous states of the beam. We show that the elastic moment is compensated by a magnetoelastic moment in the kink region, where the local magnetization of the beam is noncollinear to the applied magnetic field due to shape anisotropy. It is established that within the kink region, the MAE beam exists in a nonuniformly elastically deformed, low-symmetry magnetic state. Outside the kink, the beam's magnetization is collinear with the magnetic field, corresponding to an undeformed, high-symmetry homogeneous magnetic state.

Nonlinearly driven memory loss of incubation effects in fused silica excited by near single-cycle laser pulses

The nonlinear interaction of near-infrared ultrashort laser pulses with bulk fused silica at intensities below the catastrophic damage threshold is the birthplace of local electronic excitation events that may relax as point defects. The accumulation of defect centers creates additional sources of electronic excitation, gradually lowering the ionization threshold upon multi-pulse irradiation. However, the use of the near single-cycle sub-4 fs pulses erases in a surprising manner the contribution of defects to the damage threshold. This is the result of increasing the strong intensity clamping that limits energy density and therefore carrier collisional multiplication. Thus, the role of additional defect sources in the overall carrier population becomes secondary. In addition, the significant broadening of the near single-cycle pulse may enable impulsive depletion of defect levels, providing a possible additional pathway contributing to the suppression of nonlinear ionization memory.

Line-shape-based peak locking applied to the optical clock

In high-precision spectroscopy and quantum metrology, the stabilized system parameters at the peak of spectral lines are often required. Here, we propose a line shape-based peak locking (LSBPL) method that stabilizes system parameters at the maximum of arbitrary single-peak spectral lines. Unlike conventional proportional–integral–derivative (PID) control, which relies on a feedback function to convert an error signal into a control output, our approach exploits the intrinsic properties of the spectral line for peak locking. With application to the 171Yb+ ion optical clock using Rabi spectra, we demonstrated a comparable result to that of the PID method when the gain coefficient was set to g=0.3. The proposed LSBPL method also exhibits superior locking performance over the conventional PID method for asymmetric resonance profiles, maintaining stable closed-loop locking even when the PID method becomes ineffective. In addition, machine learning algorithms, especially random forest and support vector regression, are employed to fit single-peak spectral lines when an analytical expression is unavailable. This enables the peak-locking method to be universally applied even without requiring an explicit mathematical model, providing a flexible and generalizable tool for precision spectroscopy and quantum metrology.

Dual-barrier GeSn quantum-well lasers with operation up to 150 K

GeSn/SiGeSn quantum wells (QWs) have been investigated for the development of GeSn-based lasers. Barrier/well configurations including GeSn/GeSn and SiGeSn/GeSn were grown and characterized to evaluate carrier confinement and collection efficiency. In our previous work, a dual-barrier design (SiGeSn barrier/GeSn barrier/GeSn well) exhibited improved carrier collection efficiency for a GeSn single QW structure compared with a single-barrier configuration; however, no lasing had been reported from dual QW devices to date. Here, we report lasing from a GeSn dual-barrier single QW structure up to 140 K, with a threshold of 67 kW/cm2 at 77 K, representing a substantial threshold reduction. In addition, a 4-QW laser employing the same dual-barrier design demonstrates a clearly reduced threshold of 50 kW/cm2 at 77 K and a slightly increased maximum operating temperature of 150 K. The lower lasing threshold is attributed to decreased average carrier concentration in each well that improves the differential gain and the reduced Auger recombination rate.

Micro-array-enhanced structure–function analysis of effective thermal boundary resistance in GaN/SiN <i>x</i> /diamond heterostructures

The effective thermal boundary resistance (TBReff) of GaN/SiNx/diamond heterostructures is characterized using a micro-array-enhanced structure–function–transient dual interface method (SF–TDIM). To overcome the masking of the interfacial thermal resistance by the thick substrate in standard electrical measurements, surface-patterned etched micro-arrays are employed to reduce the effective heat-flow area and geometrically amplify the interfacial resistance contribution, while a high-precision temperature-sensing chip captures the thermal transient with negligible switching delay. For a structure with a 25-nm SiNx interlayer, SF–TDIM yields TBReff=35.2±6.4 m2K/GW (k=2), with consistent area-normalized results obtained from three array geometries. The result agrees, within the respective uncertainty intervals, with an independent transient thermoreflectance measurement on an unetched reference from the same fabrication batch. This work provides a practical electrical route with enhanced sensitivity for evaluating thermal transport across heterostructure interlayers.

Retraction: Randomized Trial of Relevance of Time-of-Day of Immunochemotherapy for Progression-free and Overall Survival in Patients With Non-small Cell Lung Cancer

Tailoring defects to boost Eu3 <b>+</b> emission in MgGeO3 phosphors

Owing to the centrosymmetric 4fn configuration of rare-earth ions, their electric-dipole 4f–4f transitions are parity-forbidden, resulting in low oscillator strengths and poor excitation efficiency. To overcome this limitation, in this work, we propose a synergistic defect-engineering strategy by introducing magnesium vacancies (VMg″) into MgGeO3:Eu3+ and systematically investigate their regulatory role in enhancing luminescence performance and the underlying microscopic mechanisms. Mg vacancies induce significant local lattice distortions around Eu3+ sites, breaking inversion symmetry and lifting the parity-forbidden nature of the electric-dipole 5D0→7F2 transition, thereby intrinsically enhancing the radiative transition probability and resulting in approximately threefold increases in both emission intensity and fluorescence lifetime. This work not only elucidates a general mechanism for synergistically tuning luminescence properties via cation-vacancy engineering but also substantially fills the research gap in Eu3+-doped Ge-based oxide systems, providing new insights for the rational design of high-efficiency and high-stability rare-earth luminescent materials.

Retraction: Neoadjuvant Adebrelimab Plus Chemotherapy in Untreated Locally Advanced Head and Neck Squamous Cell Carcinoma: Efficacy and Biomarker Insights From a Single-Arm Phase II Trial

Iron‐Catalyzed Asymmetric <i> NH ₂ </i> ‐Amination of Sulfenamides

ABSTRACT The increasing prominence of stereogenic‐at‐sulfur motifs in drug discovery and catalysis has created a growing demand for versatile synthetic methods. We describe here an Fe( TIBS PDP)‐catalyzed enantioselective NH 2 ‐amination of sulfenamides to access chiral sulfinamidines. This method accommodates a broad range of sulfenamides, enabling direct access to diverse nitrogenated stereogenic‐at‐sulfur architectures. The synthetic utility is demonstrated by the efficient preparation of pharmaceutically relevant compounds, such as an aza‐analog of drug candidate LY181984 and a PP2A modulator. Moreover, this reaction represents the first example of asymmetric NH 2 transfer using the widely employed bioinspired Fe(PDP)‐type catalysts.

Enabling thin p-GaN Ohmic contacts through ultrathin magnesium deposition and brief thermal annealing

Gallium nitride (GaN) is a key semiconductor for optoelectronic and power electronic applications. However, achieving low-resistance Ohmic contacts to p-GaN remains challenging, particularly after plasma processing. Annealing of metallic magnesium (Mg) film on p-GaN has emerged as a promising approach, but severe surface roughening limits its applicability to thin (&amp;lt;100 nm) p-GaN layers widely used in practical devices. Here, we demonstrate a capless ultrathin (&amp;lt;10 nm) Mg deposition followed by a soft anneal (600 °C, 300 s) that forms a smooth, ultra-shallow, heavily acceptor-doped surface layer. The process maintains surface smoothness while achieving a low specific contact resistivity of (1–3) × 10−4 Ω cm2 at zero-bias with linear I–V characteristics, even on plasma-etched surfaces. Quasi-vertical p–i–n diodes fabricated using this approach exhibit low leakage currents and high breakdown voltages, indicating preserved junction integrity. This work provides a practical and scalable strategy for forming robust Ohmic contacts on thin p-GaN, with broad implications for GaN-based electronic and optoelectronic devices.

Donor Selection and Human Leukocyte Antigen Loss Leukemia Relapse After Hematopoietic Cell Transplantation

PURPOSE For patients with hematologic malignancies, relapse is the leading cause of death after allogeneic hematopoietic cell transplantation (allo-HCT). Frequently, relapses are explained by immune evasion through alterations of human leukocyte antigens (HLAs), but determinants and clinical consequences remain poorly defined. METHODS We analyzed 533 relapses of hematologic cancers after allo-HCT from different donor types, conducted at 27 centers worldwide. Genomic loss of mismatched HLA (HLA loss) was assessed using a newly developed next-generation sequencing pipeline. Clinical and immunogenetic factors associated with HLA loss were evaluated. Using HLA data from approximately 5 million individuals, a web-based tool to infer HLA incompatibility phasing was developed. RESULTS HLA loss occurred in 15.6% of relapses, with significant variation according to donor type (28.7% haploidentical family, 7.2% unrelated adult, 2.7% cord blood, P &lt; .0001). The distribution of HLA mismatches across the patient's haplotypes, predicted through the phasing tool, was strongly associated with HLA loss, with an incidence of 27.6% when HLA mismatches were in the same haplotype, compared with 5.4% if present on different haplotypes ( P &lt; .0001). HLA loss affected postrelapse outcomes, abrogating the efficacy of original donor lymphocyte infusions, with significant survival advantage by second allo-HCT from a different donor. CONCLUSION The likelihood of HLA loss varies significantly according to the number and positioning of HLA mismatches between patient and donor. A newly developed phasing tool enables reliable prediction of its risk, supporting informed donor selection. Routine assessment of HLA loss at relapse is warranted, as it critically affects the success of immunologic salvage therapies.

Frequency-tunable superconducting microwave resonators based on quantum paraelectricity

Frequency tuning enables both high-sensitivity and wide-bandwidth detection in the resonator. Potassium tantalate (KTO) is a quantum paraelectric with tunable permittivity and low microwave loss at cryogenic temperature, making it promising for tunable devices. Here, we demonstrate a superconducting microwave resonator on a KTO substrate. The resonant frequency can be tuned by ∼40 MHz using a 9 V bias at 20 mK, with no observable hysteresis. The absence of hysteresis is a key metric for practical devices, addressing one of the major obstacles in other paraelectric-based tunable resonators. More interestingly, we observed that the quality factor oscillates during voltage tuning, arising from the competition between phonon hardening and charge injection. Therefore, our work provides a practical tunable resonator platform and offers a potential approach to study energy-loss characteristics in quantum paraelectrics.

Erratum: Phase I/II Study of Sonrotoclax (BGB-11417) Monotherapy in Patients With Mantle Cell Lymphoma Previously Treated With Anti-CD20 Therapy and a Bruton Tyrosine Kinase Inhibitor

2.7-kV CuCrO2/Ga2O3 heterojunction diode with stepped-mesa termination and on-state electrical stress reliability

In this work, we report vertical CuCrO2/β-Ga2O3 p–n heterojunction diodes (HJDs) incorporating a stepped-mesa termination for enhanced blocking performance and robust on-state reliability. The optimized HJD achieves a breakdown voltage of 2.71 kV with a specific on-resistance of 5.84 mΩ cm2, corresponding to a power figure of merit of 1.3 GW/cm2. TCAD simulations reveal that the stepped-mesa structure effectively suppresses electric-field crowding at the termination edge, accounting for the improved blocking capability. The on-state stability is further evaluated using a measurement-stress-measurement protocol under both constant-voltage and constant-current stress conditions. The HJD exhibits an essentially unchanged turn-on voltage and a minor increase in dynamic on-resistance, with the stress-induced variation being largely reversible after stress removal. Temperature-dependent reverse-current analysis suggests that the high-field leakage is governed by the trap-assisted Poole–Frenkel emission, yielding a trap barrier height of ∼0.35 eV. By correlating the recoverable stress response with the leakage-mechanism analysis, the stress-induced electrical variation is mainly associated with reversible electron capture and emission in preexisting trap states. This work demonstrates that stepped-mesa-terminated CuCrO2/β-Ga2O3 HJDs provide a promising route toward reliable kilovolt-class ultra-wide-bandgap power rectifiers.

Smoking in Patients With Cancer: Guidance for Delivering Effective Tobacco Treatment in Cancer Care

Continuous-wave terahertz photomixing in a silicon-compatible Ge-on-Si nano-air-channel photodiode

We demonstrate a silicon-compatible Ge-on-Si nano-air-channel photodiode for continuous-wave terahertz photomixing at 1550 nm. While nano-air-channel devices offer a promising route to ultrafast carrier transport, their implementation in a telecom-band, silicon-compatible photomixer has remained largely unexplored. The device is fabricated by a two-step buffered oxide-etch release process that forms a 50 nm air channel between the Ge surface and suspended Au/Ti electrodes. Under 1550 nm illumination, it exhibits an estimated internal quantum efficiency of 473% at 10 V, indicating that this is due primarily to localized high-field-assisted processes in the near-surface Ge region. Bias-dependent analysis reveals a transport transition near 2.5 V from leakage-dominated collection to nano-air-channel-assisted extraction, and dual-laser excitation produces continuous-wave heterodyne signals from 170 to 260 GHz. These results establish Ge-on-Si nano-air-channel photodiodes as a compact platform for silicon-compatible terahertz photomixers and photonic-electronic interfaces.

TRIPLETE But Incomplete? Accounting for Postprogression Therapy When Interpreting Overall Survival

A Radial‐Linear π‐Conjugated Polymer by Integrating Poly(Para‐phenylene Vinylene) and Cycloparaphenylene for Enhanced Optoelectronic and Electrochemical Performance

ABSTRACT Herein, we present a new class of hybrid conjugated polymer that integrates [8]cycloparaphenylene ([8]CPP) directly into poly(para‐phenylene vinylene) (PPV) frameworks, creating a π‐extended poly(cyclo(para‐phenylene vinylene)) ( [8]CPPV ). Comprehensive characterization confirmed its well‐defined alternating structure. Photophysical analyses revealed curvature‐driven electronic coupling between the radial CPP and linear PPV π‐systems, resulting in broadened absorption, red‐shifted emission, and high fluorescence quantum yield. Furthermore, [8]CPPV demonstrates excellent performance as a lithium‐ion battery anode, combining high initial capacity with stable cycling enabled by mixed pseudocapacitive and diffusion‐controlled Li + storage mechanisms. These results establish [8]CPPV as a versatile all‐carbon polymeric framework that bridges molecular nanohoops and extended π‐networks, offering a tunable platform for optoelectronic and energy storage applications.

Demonstration of ferroelectric GaN transistors with area-ratio-controlled AlScN-based MFMIS gate stack

In this study, we demonstrate an AlScN/GaN ferroelectric high-electron-mobility transistor (FE-HEMT) employing an area-ratio (AR)-controlled metal–ferroelectric–metal–insulator–semiconductor (MFMIS) gate stack. Configured with an AR of 8:1, the device exhibits a steep subthreshold slope of 26.8 mV/dec and a wide DC memory window of 5.7 V. The FE-HEMT structure facilitates AR tuning to regulate voltage partitioning, effectively preventing dielectric breakdown while enabling extensive polarization switching. Furthermore, a large pulse-induced VTH modulation of 22.9 V is achieved. The device also demonstrates robust endurance up to 3 × 107 cycles with a maintained ΔVTH of ∼7 V, highlighting the potential of the AR-controlled MFMIS FE-HEMT for GaN-based energy-efficient reconfigurable devices.