Browse Articles

CFD-enabled sustainable design and manufacturing of cooling fan for unmanned helicopter

Twist-stacked black phosphorus for wide-spectral chiral photodetection

Physico-mechanical characterization and gamma radiation shielding capability of granodiorite from Suwayqat El-Arsha, Egypt; implications for construction and natural radiation shielding

Abstract The purpose of this study is to analyze the physico-mechanical characteristics of the Suwayqat El-Arsha area Granodiorite in the Eastern Desert of Egypt as a viable construction material and an effective natural radiation shield. The granodiorite was examined using twelve petrographic microscope thin-sections and twelve samples were analyzed via X-ray Fluorescence (XRF) for their chemical compositions. Both the physico-mechanical characteristics (density, water absorption, compressive strength, abrasion resistance, and flexural strength) were tested according to standard international test methods, ASTM. The gamma radiation shielding properties were evaluated over the energy range of 0.015-15 MeV using the Phy-X/PSD software program, which was based on the chemical composition and density values obtained from the XRF analysis. The analysis of these materials showed that they are mostly composed of silicon dioxide (SiO 2  = 68.2–71.7 wt%), and their densities range from 2.61 to 2.73 g/cm 3 with water absorption levels lower than 51%. The mechanical characteristics of these materials have been demonstrated through their mechanical properties such as compressive strength between 953 and 1146 kg/cm 2 , flexural strength between 15.2 and 27.5 MPa, abrasion resistance of 13.5–16.5 mm. As for attenuation coefficients; a decrease in linear attenuation could be seen from the beginning of 20.51 cm − 1 at 0.015 MeV until reaching 0.055 cm − 1 for 15 MeV. Subsequently, there has been an increase in half-value thickness from 0.034 cm to 12.4 cm. The effectiveness of these rocks in radiation protection was determined to be 100% at ≤ 0.03 MeV and ∼20% at 15 MeV. The Gd32 sample has the greatest density, mechanical properties, and shielding ability of all tested samples. The Suwayqat El-Arsha granodiorite has overall excellent structural durability and effective gamma-ray attenuation, making it an excellent alternative to traditional construction materials and radiation shielding materials, both because it is environmentally friendly and low-cost material.

d‐π Coupling Effect for the Positive‐Valent Electrochemical Reaction Acceleration in Organic Chalcogenide Cathodes

Abstract By multi‐electron‐involved positive‐valence oxidation and negative‐valence reduction, chalcogen cathodes are expected to achieve a multifold increase in capacity. Although the strategy of organic chalcogenide cathodes can promote the positive‐valent state conversion of chalcogens, its slow kinetics severely hinder its application in practical electrochemical systems. In this study, we utilize the d‐πcoupling effect of Fe‐organic framework compounds to promote the electronic structure adjustment of chalcogens, improving the electrochemical reaction kinetics in multiple‐valence states. The Fe center employs the conjugated system to mediate charge adsorption and compensation on chalcogens during electrochemical reactions. This process enhances reaction kinetics and improves the reversibility of valence transitions. As revealed by experimental characterization and theoretical simulations, the ferrocene‐chalcogenide compound (Fc–S–Se) enables a three‐electron transfer process, facilitated by the redox coupling between S + /Se + →S 0 /Se 0 and S 0 /Se 0 →S 2− /Se 2− . The results show that the Fc–S–Se electrode demonstrates greater utilization of oxidation states (approximately 3 electrons transferred) and better rate performance (1400 and 391 mAh g −1 at 0.1 and 1 A g −1 ). It achieves an initial capacity of 1400 mAh g −1 (0.1 A g −1 ), approximately 3.3 times that of sulfoselenides (S–Se) (475 mAh g −1 ). This discovery can inspire further exploration of multivalence active site engineering for developing advanced battery cathodes.

Unlocking Room‐Temperature Phosphorescence of Polycyclic Aromatic Hydrocarbons and Beyond via External Heavy‐Atom Engineering

Abstract Room‐temperature phosphorescence (RTP) from purely organic materials holds great potential for optoelectronic and bioimaging applications; however, its realization remains challenging due to inefficient intersystem crossing (ISC) and rapid nonradiative decay. Herein, we present an effective strategy to activate and enhance RTP in heavy‐atom‐free chromophores through external heavy‐atom engineering (HAE). By dispersing these chromophores within hydrophobic halogen‐rich polymer matrices, external HAE is employed to enhance spin–orbit coupling and promote efficient ISC. The generality of this strategy is demonstrated across a series of polycyclic aromatic hydrocarbons and further extended to other heterocyclic chromophores, affording bright (phosphorescence quantum yields up to 61.6%) and long‐lived (phosphorescence lifetimes up to 273 ms) RTP materials under ambient conditions, with emission wavelengths spanning from 500 to 700 nm. This supramolecular approach circumvents the need for covalent introduction of heavy atoms to the luminophores, thereby preserving their intrinsic photophysical properties while unlocking desirable triplet‐state emissions. Overall, the current external HAE strategy provides a versatile platform for the construction of high‐performance organic RTP materials, offering new insights into the design principles of organic RTP systems and broadening the material landscape for optoelectronic and bioimaging applications.

Benchmark C ₂ H ₄ /C ₃ H ₆ Separation in MOF–COF Bilayer Membranes via Interfacial Coordination Induced Sub‐Angstrom Channel Regulation

Abstract Olefins including ethylene (C 2 H 4 ) and propylene (C 3 H 6 ) are pivotal raw materials in the chemical industry, and methanol‐to‐olefin (MTO) process provides a sustainable strategy to replace conventional petroleum‐based methods for the olefin production. The purification of olefin mixture is an essential part in the MTO process where membrane technology has emerged as a high‐efficiency and energy‐saving approach. However, it remains a critical challenge to achieve precise sieving of C 2 H 4 and C 3 H 6 due to their similar molecular size. Herein, we report an interfacial coordination induced sub‐angstrom channel regulation strategy and achieve unprecedented cut‐off shift of ZIF‐8 from C 3 H 6 /C 3 H 8 to C 2 H 4 /C 3 H 6 . Ionic covalent organic framework with crystalline structure and high‐density sulfonate groups was used as growth template for ZIF‐8 membrane. The coordination between sulfonate groups and Zn 2+ ions induced lattice contraction of ZIF‐8 framework, which is confirmed by XRD patterns and molecular dynamic simulations. The resulting membranes demonstrate a distinct cut‐off between C 2 H 4 and C 3 H 6 , achieving a C 2 H 4 permeance of 405 GPU and an exceptional C 2 H 4 /C 3 H 6 selectivity of 45, surpassing the separation performance of all reported membranes. Finally, we demonstrate the excellent scalability of this strategy by fabricating large area flat sheet membrane (>500 cm 2 ) on polymer substrates.

Synthesis and Upcycling of All‐Carbon‐Backbone Degradable Polyethylene with Dispersed On‐Chain Ketones

Abstract The challenges of photodegradable polyolefins, which have attracted much attention, persist in achieving controlled synthesis, efficient degradation, and chemical upcycling. Here, we report an all‐carbon‐backbone photodegradable polyethylene (PE) incorporating on‐chain ketones through coordination–insertion copolymerization of ethylene and the optimal phenyl vinyl ketone (PVK). This strategy enables precise control over the chain structure, including PVK dispersed distribution (0.3–8.3 mol%), saturated C sp3– C sp3 backbone, and enhanced surface properties while retaining thermomechanical properties. Crucially, this is the first report that achieves the quantitative conversion (100%) of ketone units in photodegradable PE under ambient UVA light ( λ = 390–395 nm) with high efficiency. Mechanistic studies on photodegradation reveal two competitive pathways: Norrish Type II scission and Norrish–Yang cyclization (∼50% for each), yielding well‐defined telechelic PE oligomers. These insights allow predictable control over molecular weight of degraded product, enabling tailored polymer design. Photodegradation coupled with in situ thiol‐ene click chemistry generates hydroxyl‐terminated telechelic PE oligomers, which are upcycled into PLA–PE–PLA triblock copolymers, exhibiting excellent compatibility in HDPE/PLA blends. This work bridges the gap between PE degradation and upcycling, unifying customizable synthesis, controlled degradation, and value‐added upcycling into a single platform for sustainable polyolefins.

Iron‐Catalyzed Alkynylation of Strong Aliphatic C─H Bonds

Abstract The development of synthetic catalysts capable of replicating cytochrome P450's remarkable C─H activation proficiency while suppressing oxygen rebound presents a fundamental challenge in catalysis, yet holds transformative potential for alkane functionalizations. Herein, we report an iron/EtBCMOM (L‐cystine‐based ligand) catalytic system for the selective distal methylene C(sp 3 )‐H alkynylation of alkanes using alkynyl sulfones. This catalytic paradigm establishes a robust platform for the direct transformation of inert C(sp 3 )─H bonds into versatile alkyne functionalities, exhibiting exceptional predictability in regioselectivity and accommodating an expansive substrate scope (>60 structurally diverse examples). The technology unlocks previously inaccessible chemical space, enabling single‐step derivatization of natural products, medicinally relevant molecules, and commodity feedstocks at traditionally unreactive positions.

Where's the Salt? Sensing the Ionic Environment of the Air–Organic–Water Interface Using an Azide Probe

Abstract Understanding ionic behavior at aqueous interfaces is vital to fields spanning environmental chemistry, microdroplet reactivity, and electrochemical systems. Yet, whether ions accumulate or are depleted at aqueous boundaries remains debated. Using an uncharged, surface‐anchored azide probe, we find that even at 5 M salt concentrations, the air–organic–water interface is depleted of small, inorganic ions, contrasting pronounced effects in bulk. Only under water‐in‐salt conditions (>10 M ZnCl 2 ) does evidence of direct cation coordination emerge at the interface. These findings extend the stratified salt model to the air–organic–water interface and provides molecular‐level insights into interfacial reactivity, ion partitioning, and “on‐water” transformations.

Programmed Pore Engineering in an Isoreticular Triazole–MOF Series for One‐Step Ethylene Separation

Abstract Ethylene (C 2 H 4 ) purification from CO 2 /C 2 H 2 /C 2 H 4 ternary mixtures is industrially crucial yet remains highly challenging. Current metal–organic frameworks (MOFs) lack the ideal CO 2  > C 2 H 2  > C 2 H 4 adsorption sequence necessary for stepwise removal of impurities. Herein, we address this gap through precise pore environment tuning within an isoreticular series of zinc–triazole MOFs. By modulating the number and position of ─NH 2 /─CH 3 groups on the ligand, we precisely control pore chemistry from one‐dimensional (1D) channels to two‐dimensional (2D) interconnected channels, which successfully achieves the targeted adsorption order. The unilateral amino groups in the optimized MOF, ZSTU‐30 , create unique supramolecular interlocking sites that strongly bind CO 2 while mitigating interactions with C 2 H 4 and C 2 H 2 . Consequently, ZSTU‐30 enables the direct production of polymer‐grade C 2 H 4 (> 99.9%) from a ternary gas mixture in a single step, with an exceptional C 2 H 4 productivity of 3.18 mmol g −1 . The CO 2 –host interaction mechanism is elucidated by in situ single‐crystal X‐ray diffraction and theoretical calculations, which reveal multiple supramolecular interactions at the adsorption sites. Combining excellent water and pH stability, ZSTU‐30 stands out as a robust and promising physisorbent for one‐step C 2 H 4 purification.

Pd‐Induced Cu Site Differentiation in Pd ₁ Cu/Ag–N–C Catalyst Enables Asymmetric CO─CHO Coupling for Efficient CO ₂ ‐to‐C ₂ H ₄ Conversion

Abstract Electrochemical CO 2 reduction to ethylene (C 2 H 4 ) presents a pivotal strategy for industrial decarbonization and carbon valorization but is persistently hindered by the intrinsic high kinetic barrier for symmetric *CO─*CO coupling on conventional Cu catalysts. To surmount this fundamental challenge, we synthesized a tandem Pd 1 Cu/Ag–N–C catalyst that achieves site differentiation of the surface Cu. The Pd 1 atom induces electronic heterogeneity by creating two electronically distinct Cu sites. The Pd‐proximal sites promote *CO protonation to *CHO by leveraging Pd assisted H 2 O dissociation, and Pd‐distal sites stabilize *CO. This synergistic division unlocks a highly efficient asymmetric C─CHO coupling pathway. Operando spectroscopy and DFT calculations confirm that the engineered pathway lowers the critical C─C coupling barrier by ∼50%. The Pd 1 Cu/Ag–N–C catalyst delivers a peak C 2 H 4 Faradaic efficiency of 78.8% (±2.5%) with a partial current density of 441 mA cm −2 at ‐0.97 V versus RHE in a flow cell, while maintaining excellent operational stability. This work validates asymmetric CO─CHO coupling as a superior route for C 2 H 4 electrosynthesis by introducing a generalizable design paradigm of precisely steering reaction pathways on multi‐carbon electrocatalysts.

Alkenylthianthrenium Salts as Synthetic Equivalents of (Cyclo)alkynes in Azide Cycloaddition Reactions

Abstract Cycloalkynes are highly reactive coupling partners in a variety of cycloaddition manifolds, but the synthetic utility of cycloalkynes with fewer than 8 atoms is limited by their fleeting stability. To expand access to heterocycles derived from formal cycloadditions to cycloalkynes, we have developed a methodology in which alkenylthianthrenium salts are used as synthetic equivalents of cycloalkynes in reactions with azides. This methodology enables expedient access to a variety of 1,2,3‐triazoles from alkene building blocks in two steps, including triazoles fused with 5‐, 6‐, 7‐, and 8‐membered carbocycles. Rather than serving as precursors to in situ‐generated alkynes, we discovered that many alkenylsulfonium salts react with azides as dipolarophiles, generating 1,2,3‐triazoles via a distinct cycloaddition–elimination mechanism. We show that this methodology is viable for both acyclic and cyclic alkenylsulfonium salts and demonstrate its applications as a tool for the synthesis of new small molecule heterocycles and functional polymeric materials.

Long Single‐Stranded DNA with Site‐Specific Modifications to Enable Single‐Base‐Resolution Epigenetics

Abstract We report a method for synthesizing site‐specifically modified long single‐stranded DNA (ssDNA) with high purity and fidelity. With the successful synthesis of long ssDNA carrying different 5‐methylcytosine (5mC) patterns, single‐base‐resolution analysis of 5mC epigenetic dynamics at specific genomic loci were enabled in mammalian cells. The results revealed that the density of 5mC sites synergistically correlated with their maintenance. This study opens new avenues for precise epigenetic manipulation and therapeutic applications.

Global risk pooling mitigates financial risk from drought in hydropower-dependent countries

Abstract More than 50 countries rely on hydropower for over 25% of their electricity generation, making them vulnerable to drought and resulting revenue losses. Governments can offset financial losses for publicly-owned hydropower generators, but this can create fiscal pressures and lead to negative consequences, such as lower bond ratings. Index-based financial instruments, used to manage weather-related risk, offer an alternative, though data collection and index design are challenging. Using remotely sensed hydrometeorological data, we develop index insurance contracts to manage drought-related financial risk for hydropower-dependent countries. Low correlations in drought across these countries allow cost reductions when risks are pooled. Pooling the contracts yields average savings of 54% compared to individual risk management via reserves. These findings indicate that pooled index insurance can strengthen financial resilience in countries dependent on hydropower and support governments in mitigating drought-related economic risks.

High‐Concentration Alcohol Generation in Bipolar Membrane CO Electrolyzer

Abstract Electrochemical reduction of carbon dioxide and carbon monoxide offers an electricity‐powered route to make multicarbon liquid products. However, in conventional systems employing anion exchange membranes (AEMs), significant liquid product crossover leads to dilute product streams, increasing separation costs; and also produces unwanted anodic oxidation, further decreasing overall efficiency. Here, we report a forward‐biased bipolar membrane (FB‐BPM) system that achieves <10% liquid product crossover while sustaining a highly alkaline environment near the cathode, suppressing ethylene and hydrogen and favoring liquid products. By tuning catalyst composition to modulate the adsorption of *H and *OH, we steer selectivity toward acetate and alcohols. Using the FB‐BPM system, we achieve >25 wt% acetate on CuZn and >15 wt% alcohols on CuSn directly from the cathode outlet stream.

Spin-state engineering of single titanium adsorbates on ultrathin magnesium oxide

Near-infrared light-driven nanomotors-based microneedles for the active therapy of bacterial infected acne

Glutamatergic projection neurons in the basal forebrain underlie learned olfactory associational valence assignments

Highly Selective Electrosynthesis of Glycine from Glyoxylic Acid and Nitrate via Stabilizing the NH ₂ OH Intermediates

Abstract Electrochemical C–N coupling reactions have emerged as an important strategy for synthesizing value‐added organic compounds under ambient environment, among which glycine is of practical importance for various biological activities and pharmaceutical synthesis. However, such synthesis suffers from limited selectivity due to the complex reaction pathways. In this study, we report the highly selective synthesis of glycine from the electrocatalytic co‐reduction of nitrate and glyoxylic acid via stabilizing the intermediates of NH 2 OH and optimizing the absorption of glyoxylic acid on copper‐based model catalysts. Theoretical calculations and operando measurements indicate that CuSn alloys promote the generation of NH 2 OH and optimize the absorption of glyoxylic acid, thereby facilitating the precise coupling of C–N groups to synthesize glycine. Consequently, the CuSn electrocatalyst delivers an excellent performance for the co‐reduction to generate glycine with a maximum Faradaic efficiency and selectivity of 78.69% and 99.32%, respectively. Moreover, the CuSn catalyst enables the production of 0.73 g of glycine with a conversion rate of 100%, respectively, in large‐scale synthesis. Techno‐economic analysis reveals that the total cost for the proposed method is 1158.88 $ ton −1 , 1.78‐fold lower than the commercial price (2060.44 $ ton −1 ), suggesting that the electrosynthesis of glycine in our system is a feasible and profitable route.

Robust and interpretable prediction of gene markers and cell types from spatial transcriptomics data

Abstract Spatial transcriptomics (ST) links tissue morphology with gene expression values, opening new avenues for digital pathology. Deep learning models are used to predict gene expression or classify cell types directly from images, offering significant clinical potential but still requiring improvements in interpretability and robustness. We present STimage as a comprehensive suite of models to predict spatial gene expression and classify cell types directly from standard H&E images. STimage enhances robustness by estimating gene expression distributions and quantifying both data-driven (aleatoric) and model-based (epistemic) uncertainty using an ensemble approach with foundation models. Interpretability is achieved through attribution analysis at single-cell resolution integrated with histopathological annotations, functional genes, and latent representations. We validated STimage across diverse datasets, demonstrating its performance across various platforms. STimage-predicted gene expression can stratify patient survival and predict drug response. By enabling molecular and cellular prediction from routine histology, STimage offers a powerful tool to advance digital pathology.