Browse Articles

Deprotonation suppressing via competitive proton transfer control for efficient perovskite solar cells

Abstract Despite the efficacy of the methylammonium chloride (MACl) additive strategy in stabilizing the α-phase of formamidine-based perovskite materials, a persistent and formidable challenge from the irreversible deprotonation of MA + cation still bothers the fabrication of satisfactory formamidine (FA)-based perovskite photosensitive layers, thereby hindering the performance improvement of resultant perovskite solar cells. To confront this obstacle, numerous methodologies have been proposed and demonstrated their potential, particularly those leveraging additives enriched with carboxylic acid functional groups (-COOH). However, these approaches remain inherently flawed due to the deleterious competitive proton transfer from hydrogen iodide (HI) to the excess -COO - species, which undermines the integrity of the entire strategy. Herein, an innovative methyl trifluoroacetate (MTFA)-assisted technique is pioneer conducted to control the competitive proton-transfer through its stepwise hydrolysis reaction and the gentle release of -COOH derived from trifluoroacetic acid (TFA) byproduct. By this way, the perovskite precursor solution deprotonation is suppressed and the shelf life of corresponding perovskite precursor solution is greatly prolonged to over 22 days. Concurrently, the robust affinity of -COOCH 3 or byproduct -COOH groups toward uncoordinated Pb 2+ has also been proven to enable the fine-tuning of perovskite crystallization dynamic, while the residual CF 3 COO - species distributed in the buried interface of perovskite are considered to offer an additional improvement in film carrier behavior via the halogen vacancies passivation. Consequently, high-quality perovskite films with conspicuous crystalline structure, surface morphology and carrier characteristic were obtained, achieving a champion device fabricated from 22 days aging perovskite precursor solution (PPS) with a power conversion efficiency of 26.35% and retaining 94.75% of its initial efficiency after 1464 h of humidity exposure.

First-principles prediction of altermagnetic topological insulators in the hydrogenated Ti2X2O (X = As, Sb) monolayers

Altermagnetism, a distinct magnetic phase beyond traditional ferromagnetism and antiferromagnetism, offers a promising platform for realizing novel topological quantum states. Utilizing first-principles calculations, we have systematically investigated the electronic, magnetic, and topological properties of hydrogenated Ti2X2O (X = As, Sb) monolayers. Upon surface hydrogenation, the structural stability is significantly improved, and the formed Ti2X2OH2 monolayers exhibit a typical altermagnetic characteristic. Interestingly, without the spin–orbit coupling (SOC), a Weyl semimetallic behavior is present in the Ti2As2OH2 system, which possesses four Weyl cones and a p–d band inversion around the Γ point. After the inclusion of SOC, a substantial bandgap of 0.15 eV opens at the Fermi level, transforming the Ti2As2OH2 monolayer into an altermagnetic topological insulator. The nontrivial topology is characterized by a quantized spin-Hall conductance, a nonzero spin Chern number, and one pair of helical edge states in the bulk gap. The similar nontrivial behavior also exists in the Ti2Sb2OH2 monolayer, which has a larger gap of 0.19 eV. Through strain engineering, a nontrivial-to-trivial topological transition is induced in the Ti2As2OH2 monolayer, whereas for the Ti2Sb2OH2 system an insulator-to-metal transition will happen. Our study highlights the Ti2X2OH2 systems as compelling candidates for achieving unconventional altermagnetic topological states.

Large-sample PCA eigenvectors stabilize cortical thickness components and improve small sample brain behavior prediction

Context-specific life cycle emissions pathways for EU buildings and construction

Abstract The European Union aims to reduce greenhouse gas emissions by 55 percent by 2030 relative to 1990 and achieve climate neutrality by 2050. Yet, translating these targets into pathways for buildings and construction is challenging across diverse national contexts. We model building stocks for the twenty-seven Member States of the European Union and evaluate 4096 life cycle emissions scenarios, considering national capacities. Here we show that, over 2020–2050, achieving these targets would require avoiding 8.53 billion metric tons of carbon dioxide equivalent, approximately ten years of emissions at 2020 levels. Mostly relying on improving energy efficiency and material production would exceed national capacities by 2.72-billion-ton, 32 percent of the required reduction. A combined approach that also reduces per capita space demand, applies circularity measures, and uses bio‑based materials could achieve an additional 2.19 billion tons within national capacities. For each country, we identify the strategies that maximize projected reductions to inform policy design.

Porous Phenazine‐bridged Tetraoxa[8]Circulenes for Selective Gold Recovery and Heterogeneous Catalysis

ABSTRACT The sustainable recovery of precious metals is critical for securing strategic resources while reducing the environmental footprint of mining. Among these, the selective recovery of gold from electronic waste represents a particularly attractive yet challenging target. Herein, we report the synthesis of phenazine‐based porous tetraoxa[8]circulene, PpTOC, incorporating heterocyclic crown ether moieties for efficient gold capture. The PpTOC combines a high surface area over 1200 m 2 g − 1 with aza‐crown ether‐like cavities and high heteroatom content, enabling high gold uptake capacities of up to 860 mg g − 1 under acidic conditions. Importantly, the polymer demonstrates selective recovery of gold from electronic waste even in the presence of high concentrations of competing metal ions such as copper. The recovered material, containing a mixture of Au(III), Au(I), and Au(0) species, has been directly employed as a heterogeneous catalyst in a sequential alkylation–annulation reaction. Critically, switching from aprotic toluene to protic ethanol redirects the reaction outcome from alkylation to annulation, enabling divergent product selectivity using the same heterogeneous catalyst simply by changing the solvent.

Achieving high spin–orbit torque efficiency and robust thermal stability in the sputter-grown topological bilayer BiSb/Pt

Topological insulators (TIs) have emerged as promising candidates for spin–orbit torque (SOT) devices, owing to their high charge-to-spin conversion efficiency. However, integrating TIs, such as polycrystalline Bi0.9Sb0.1, into conventional complementary metal-oxide-semiconductor (CMOS) processes poses significant challenges, as their SOT efficiency is compromised by the elevated thermal budgets required by back-end-of-line (BEOL) processing. In this work, we examine the thermal stability of sputter-grown Bi0.9Sb0.1/Py films. While the system exhibits a high SOT efficiency (ξFMR = 0.83) after annealing at 230 °C, the efficiency decreases by ∼65% when the annealing temperature is increased to 400 °C. To reduce this degradation, a 1.5 nm Pt insertion layer is added to the Bi0.9Sb0.1/Py interface. This engineering approach effectively reduces interfacial intermixing, enabling the stack to maintain a strong SOT efficiency of 0.85 even after annealing at 400 °C. Consequently, our results contribute to the development of BiSb-based spin–orbit torque magnetic random-access memory (SOT-MRAM) and its integration with CMOS technologies.

Automated detection and fissure width quantification of ground fissures using FastICA-enhanced distributed fiber optic sensing

Role of garnet shaping the 660-km seismic discontinuity

Controlling the optical-feedback-instability of VCSELs through inter-mesa coupling

The rapid advancement of artificial intelligence and cloud computing has led to a strong demand for high-speed vertical-cavity surface-emitting lasers (VCSELs). Omitting the optical isolator in short-range modules based on VCSELs reduces costs but requires higher optical-feedback tolerance. Thus, exploring VCSELs with strong resistance to optical feedback is pivotal for the development of high-speed short-range optical modules. This study proposes coupled-mesa VCSELs (CM-VCSELs) as a robust strategy against external feedback. We investigated the feedback effects in VCSELs experimentally and numerically by systematically varying the inter-VCSEL distance. Compared to VCSELs without lateral coupling, we found that the inter-VCSEL coupling leads to significantly improved stability with reduced linewidth and relative intensity noise. Furthermore, there is an optimum inter-VCSEL distance where the linewidth is the smallest for a given optical-feedback strength. To verify the conventional understanding, we extracted the linewidth enhancement factor (LEF), confirming that the stability improvement stems from the lower LEF. Our study demonstrates that CM-VCSELs offer a large design tolerance window for VCSELs, and that feedback instability can be controlled through inter-mesa distance. Our strategy provides a low-cost manufacturable approach to VCSEL-based short-range high-speed modules.

Electrical discharge machining of Ti6Al4V in deionized water: surface integrity and wear response for medical applications

Measuring multi-site pulse transit time with an AI-enabled mmWave radar

The C─C Bond‐Centric Mechanism in Electrocatalytic Waste Polyethylene Terephthalate Valorization

ABSTRACT Plastics have revolutionized our lives, especially polyethylene terephthalate (PET) plastics; however, their exponential consumption and inadequate management have exacerbated global plastic pollution. To address this, renewable energy‐driven electrocatalysis offers a sustainable route to upcycle waste PET into value‐added chemicals, simultaneously delivering economic and environmental advantages. This minireview summarizes recent advances in electrocatalytic PET‐derived ethylene glycol (EG) conversion, establishing a framework based on the fate of the C─C bond (cleavage, maintenance, or coupling) to precisely access C 1 (formic acid, formamide, hydroxymethylsulfonate), C 2 (glycolaldehyde, glycolic acid, oxalic acid), and C 3+ (α‐hydroxycarboxylic acid) products. We place particular emphasis on the bond‐centric mechanisms, discussing the decisive factors that govern the reaction pathways and performances. Finally, a forward‐looking perspective is provided to guide future innovations in sustainable PET valorization and circular chemical manufacturing.

Evaluation of Si thin film formed from Si0.7Ge0.3/Si/Si0.7Ge0.3-stacked layers with CF4/H2 plasma for Si-nanosheet formation toward GAA transistor application

We investigated the influence of selective SiGe etching process condition using CF4/H2 plasma on defect formation in the Si layer. Total photoelectron yield spectroscopy and conductive-atomic force microscopy measurements revealed that the H2-dilution ratio significantly affected defect formation. In particular, defect formation was effectively suppressed, and uniform electron transport in the Si layer was achieved after the etching of Si0.7Ge0.3 with CF4/H2 plasma at 5% H2 dilution. Furthermore, we successfully demonstrated the formation of an ultrathin Si-nanosheet (Si-NS) using CF4/H2 plasma at 5% H2 dilution and evaluated the local electron-transport properties to investigate surface defect uniformity in the Si-NS. These results will lead to the development of highly reliable gate-all-around Si-NS field-effect transistors through an all-dry process.

CL-ODGAN: an unpaired attention-guided GAN framework for remote sensing image dehazing

Comparative analysis of the cellular landscape in mammalian striatum

Abstract The dorsal striatum is important for highly specialized functions including movement, learning, and habit formation. However, it is not known if species-specialized behaviors are associated with cellular specializations in the striatum. Here, we compared single-nucleus RNA sequencing (snRNA-seq) data from human, chimpanzee, rhesus macaque, common marmoset, and pale spear-nosed bat caudate (CN) and putamen (Pu) separately as well as mouse caudoputamen (C-Pu), which represents divergence among species spanning approximately 94 million years of evolution. We observed a lower neuron-to-glia ratio in primate striata compared to non-primates, reflecting the allometric scaling of neuron density and relative glia density invariance in larger brains. Among neurons, eccentric spiny projection neurons (eSPNs) - an SPN of unknown function - showed significantly lower proportions in non-primate striata for both CN and Pu. Focusing on the heterogeneity within interneurons, we identified two bat striatal interneuron cell types that are nearly absent in other species: which express LMO3 , and co-express FOXP2 and TSHZ2 . Other striatal interneurons also exhibited differential abundance between primates and non-primates. In summary, we provide a comprehensive snRNA-seq dataset of dorsal striatum, identify two distinct, previously uncharacterized populations of bat interneurons, and uncover fundamental cellular composition differences between primate and non-primate striata.

Bottom‐Up Coacervate‐Based Artificial Cells: Integrating Cellular Hallmarks into Complex Life‐Like Systems

ABSTRACT Living cells are remarkably sophisticated entities that form the basis of life. Bottom‐up artificial cell research focuses on reconstructing their essential functions and behaviors in life‐like compartments using synthetic and natural building blocks, which can advance our understanding of fundamental biological processes and drive technological and biomedical applications. In this review, we focus our discussion on recent developments in bottom‐up artificial cell research with a particular emphasis on coacervate‐based artificial cell systems that integrate multiple cellular hallmarks. We delineate how enhanced structural mimicry through organized compartmentalization affords improved control over function. We then examine how energy supply can be coupled to metabolic processes, growth, and adaptive responses in artificial cells. We also survey emerging systems that enable artificial cells to communicate with other artificial and living cells through responsive signaling and functional interactions. Finally, we present our vision on the opportunities and directions for artificial cell research moving forward.

Low-loss Nb on Si superconducting resonators from a dual-use spintronics deposition chamber and with acid-free post-processing

Magnetic impurities are known to degrade superconductivity. For this reason, physical vapor deposition chambers that have previously been used for magnetic materials have generally been avoided for making high-quality superconducting resonator devices. In this article, we show by example that such chambers can be used for this purpose; with Nb films sputtered in a chamber that continues to be used for magnetic materials, we demonstrate compact (3 μm gap) coplanar waveguide resonators with low-power internal quality factors near one million. We achieve this using a resist strip bath with no post-fabrication acid treatment, which results in performance comparable to previous strip baths with acid treatments. We also find evidence that this improved resist strip bath provides a better surface chemical template for post-fabrication hydrogen fluoride processing. These results are consistent across three Si substrate preparation methods, including a 700 °C anneal. These results will inform nanofabrication for other superconducting materials and the integration of magnetic materials for hybrid systems.

Athletes’ performance and injury management in sports training using association rules and data mining techniques

GABA signaling in NG2 glia mediates empathy-like behavior under observational social defeat

Oxygen reduction for p-type TeOx thin-film transistor

We investigated p-type TeOx thin films fabricated by vacuum deposition using a mixture of TeO2 powder and W powder in Al2O3 crucibles and evaluated its thin-film transistor (TFT) characteristics. P-type TeOx thin films were obtained when W was added at a weight ratio of 15% or more relative to TeO2. However, the films became insulators and exhibited no electrical conductivity when the ratio was 10% or less. X-ray photoelectron spectroscopy analysis revealed that the TeOx thin films contained approximately 5% or more Te–Te bonds. Because W–O bonds exhibit a higher dissociation energy than Te–O bonds, TeO2 was considered to be reduced by W. In addition, W was not present in the film and was used solely for the reduction of TeO2. The results manifest that when TeOx TFTs are fabricated by vacuum deposition, the addition of an appropriate amount of reducing agent to the raw material is essential to form an adequate amount of Te–Te bonds.