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Corrosion induced failure mode in reinforced concrete beams based on experiments and finite element predictions
Synthesis of Six Natural Products Enabled by Selective Hydroxylation of Orcinaldehyde‐Like Substrates With an Enzyme Library
ABSTRACT Achieving selective oxygenation chemistry offers a powerful strategy for streamlining routes to complex target molecules, yet the development of site‐selective C–H functionalization reactions is challenging. Several enzyme families are capable of catalyzing C–H hydroxylation reactions and, in principle, provide an attractive solution for achieving selective oxidative transformations. In practice, however, the difficulty of identifying a biocatalyst suited to a specific synthetic target often renders chemoenzymatic strategies impractical. For example, biosynthetic enzymes such as CitB and ClaD can mediate site‐selective benzylic hydroxylation, enabling access to select natural products that share structural features with their native substrates. Nonetheless, such approaches typically lack generality and do not readily extend to broader collections of natural products. Here, we explore the previously unstudied natural sequence space surrounding biosynthetic hydroxylases CitB and ClaD to generate a bespoke panel of uncharacterized enzymes that collectively expand the substrate scope of biocatalytic benzylic hydroxylation reactions. Development of this curated biocatalyst panel enabled the hydroxylation of a set of orcinaldehyde‐like substrates, which were further elaborated to six natural products.
Removing hydrogen sulfide and carbon dioxide from natural gas using iron oxide nanoparticles and a magnetic field
Abstract This paper is one of the few studies that examine the use of water-amine nanofluid along with iron oxide nanoparticles with volume fraction ϕ = 0 to 0.05 to remove acid gases ( $${\text{H}}_{2}\text{S}$$ and CO 2 ) from natural gas. In this research, real-size refinery equipment was simulated using Fluent software, and the effects of nanoparticles and a constant magnetic field on increasing the heat transfer rate and the removal rate of acid gases from natural gas were investigated. The results show that in the absorption tower, with the increase of the Reynolds number from Re = 8000 to 24,000, the Nusselt number also increases, and with the rise of the $$\phi$$ to 0.05, the mole fraction of $${H}_{2}S$$ in the nanofluid increases to 34%, and the mole fraction of CO 2 increases to 23%. Additionally, as the temperature increases, the dynamic viscosity of the nanofluid decreases. However, when the volume fraction (ϕ) increases to 0.05, the dynamic viscosity of the nanofluid approximately increases by 10% in the temperature range of 45 to 56 $${^\circ{\rm C} }$$ . In this research, magnetic field intensities ranging from 0 to 20,000 Gauss were used. With $$\phi$$ =0.01, the mentioned magnetic fields increase the mass transfer coefficient to 13.26%. With $$\phi$$ = 0.05, the mass transfer coefficient decreases to 4.44% due to the increased probability of nanoparticles settling. The maximum mass transfer coefficient is up to 67.4%, which is observed in $$\phi$$ = 0.03, with the magnetic field intensity of 20,000 gauss. A limitation of this research was the failure to evaluate the effect of changing the fluid flow regime on other refinery equipment.
T‐Shaped Stibenium(III) Cation: Hydrostibination Without Sb─H Bond
ABSTRACT The hydrostibination of alkenes represents a largely underdeveloped transformation, owing to the intrinsic lability of the required Sb─H reagents. We now show that an Sb─H bond is not needed. The structurally constrained, amidophenolato‐pyridyl supported T‐shaped stibenium(III) ion undergoes anti ‐Markovnikov hydrostibination of a broad range of alkenes in excellent yields. Spectroscopic and computational analyses reveal a polarizable, redox‐confused Sb– π system in the cation, whereas its reactivity follows closed‐shell ionic pathways characteristic of a Lewis‐acidic Sb(III) center. Mechanistic studies support element–ligand cooperativity (ELC) with the hydride equivalent for hydrostibination originating from the ligand scaffold after substrate activation at antimony. The resulting stiba‐alkanes can be transformed quantitatively into haloalkanes. This work establishes a viable strategy for hydroelementation with heavy p ‐block elements while circumventing weak and labile E─H bonds.
Design of an intelligent security system for cyber-attack detection in petrochemical SCADA networks based on a hybrid artificial neural network and Krill-Herd algorithm
Strain Effect Triggers Pt Adaptive Mechanism to Construct Brønsted Acid Microenvironment for Ampere‐Level Hydrogen Production From Alkaline Seawater
ABSTRACT Intermittent renewable energy‐driven seawater hydrogen production can alleviate freshwater resource pressure and is of great significance in future energy systems. However, the localized microenvironment changes at the cathode and the strong interactions between other impurities and the electrolyzer lead to performance degradation and reduced equipment lifespan. Here, we report an alkaline seawater cathode catalyst for hydrogen production in an anion exchange membrane water electrolyzer (AEMWE). This catalyst can dynamically adjust the local reaction environment on the cathode surface. Through the reversible changes in the oxidation state of Pt in high‐entropy intermetallic compounds, a Brønsted acid‐like environment is formed near the reaction interface, inhibiting the formation of precipitates. In situ characterization confirmed that this Brønsted acid‐like environment can promote hydrogen production from alkaline seawater. Using alkaline seawater electrolysis, AEMWE operated stably for over 2000 h at an industrial‐grade current density of 1.0 A cm −2 (1.74 V).
Prebiotic and postbiotic synergy alleviates age-related dysbiosis and inflammation in mice
Abstract Advances in medicine and veterinary medicine extend the lifespan of humans and companion animals. Interest in nutritional strategies to support healthy aging consequently increases. In this study, the effect of 11% scFOS+ supplementation (a blend of short-chain fructo-oligosaccharides and yeast-derived postbiotics) in 18-month-old mice was evaluated, compared with aged or adult mice of 9 weeks old on a control diet. Bodyweight and food intake were monitored throughout the 56-day study. Faecal samples were collected on days 0, 28, and 56, and caecal samples at the end of the study (day 56), for microbiota analysis. Immune markers, including cytokine production in tissues and blood and toll-like receptor (TLR) expression, were analysed at day 56. The results showed that scFOS+ supplementation reduced the abundance of potentially pathogenic bacterial species and enhanced the growth of beneficial genera like Allobaculum and Bifidobacterium , aligning the microbiota profile of aged mice more closely with that of adult mice. The pro- and anti-inflammatory balance was maintained in supplemented old mice, and their TLR expression patterns resembled those observed in adults. In conclusion, combining prebiotics and postbiotics modulates immune responses in aged mice, restoring adult-like levels through gut microbiota changes and suggesting potential for promoting healthy aging in companion animals.
Visible Light‐Driven Copper‐Catalyzed Asymmetric Synthesis via Sequential C(sp <sup>3</sup> )─C(sp <sup>3</sup> ) Bond Scission
ABSTRACT The selective and consecutive cleavage of C(sp 3 )─C(sp 3 ) bonds while simultaneously governing chemo‐, regio‐, and stereoselectivity constitutes a long‐standing unresolved challenge in synthetic chemistry. Here, we present a visible light‐driven copper catalysis platform that surmounts this obstacle. A chiral bisoxazoline copper complex acts as a multifunctional catalyst, and a tailored sodium sulfoxylate additive modulates the metal coordination sphere, altogether eliminating the requirement for an external photosensitizer. This streamlined system promotes twofold C(sp 3 )─C(sp 3 ) fragmentation of cyclobutanols and subsequent coupling with imines to construct quaternary carbon stereocenters, releasing ethylene as the sole byproduct. Integrated experimental and computational investigations delineate an unprecedented cascade mechanism: photoinduced ligand‐to‐metal charge transfer (LMCT) initiates strain‐release ring opening, a copper‐mediated β ‐cleavage executes the second fragmentation, and a highly enantioselective radical addition to the imine completes the stereodefined assembly. The sodium sulfoxylate additive proves indispensable for rerouting the pathway toward the second cleavage over premature radical trapping and elevating enantioselectivity to as high as 99% ee. By demonstrating rigorous kinetic command over multiple C(sp 3 )─C(sp 3 ) cleavages within a single cascade, this work establishes a new paradigm for photochemical asymmetric synthesis.
Comparative chloroplast genomes and phylogenetic analysis of the genus Stephania (Ranunculales: Menispermaceae): implications for molecular marker development
Interfacial Entropy Drives Crystallization of Covalent Framework Membranes for Precise Ionic Separation
ABSTRACT Achieving highly crystalline covalent organic framework (COF) membranes is essential for efficient mass transport but remains a longstanding challenge due to the inherent trade‐off between structural regularity and processability. Herein, we report an entropy‐regulated interfacial crystallization strategy that redirects membrane formation from kinetically trapped disorder to thermodynamically favored crystallization. By introducing ion‐dipole interactions at the interface, the configurational entropy of monomers is markedly reduced by 326.9 J mol −1 K −1 , enforcing ordered preorganization of monomers. Besides, solvent‐mediated diffusion induces framework growth beneath the nascent layer, giving rise to an asymmetric membrane structure composed of a dense, highly crystalline selective layer supported by a fibrous macroporous sublayer. The resulting membrane exhibits long‐range ordered channels, a high surface area up to 1721 m 2 g −1 , and enhanced mechanical robustness. Benefiting from these ordered channels, the membrane delivers a high Cs + permeation rate of 0.17 mol m −2 h −1 and an exceptional Cs + /La 3+ selectivity of 292 in mixed ion systems. This work establishes interfacial entropy regulation as a general and effective route for controlling crystallization in interfacial systems, offering new insights into the rational fabrication of framework‐based separation membranes.
Design, fabrication and testing of an optimized single-axis MEMS capacitive accelerometer using wet etching for improved noise stability
Atomically Precise NHC‐Protected Alkylgold Nanoclusters
ABSTRACT Alkylgold complexes are of paramount significance in organometallic chemistry owing to their catalytic relevance, yet atomically precise alkylgold(0) species remain unexplored. Herein, we report the first structurally authenticated alkyl‐ligated Au(0) nanocluster, [Au 64 (NHC i Pr ) 14 Et 10 Cl 6 ](BF 4 ) 2 ( Au 64 , NHC i Pr = 1,3‐diisopropylimidazolin‐2‐ylidene, Et = ethyl), synthesized via a facile base‐mediated alkylation strategy with alkylboronic acids as precursors. X‐ray crystallography reveals a box‐shaped Au 16 @Au 40 @Au 8 architecture with near D 4 h symmetry, bearing 14 NHC ligands on the longitudinal plane and 10 alkyl ligands at both ends, all bound in a terminal coordination mode. DFT calculations demonstrate that ethyl→Au σ‐donation dominates the orbital interaction, accompanied by partial negative charge accumulation on the alkyl carbons. Although the weak nucleophilicity associated with ethyl groups, protonation of the Au–ethyl bond is thermodynamically favored, and C(sp 3 )–C(sp 3 ) cross‐coupling readily available with strong electrophiles. Notably, β‐hydride elimination of ethyl moieties is directly observed under alkaline conditions, providing the first experimental evidence for this critical transformation at Au(0) centers. This work not only establishes an efficient synthetic route to alkyl‐functionalized gold NCs but also delivers comprehensive insights into the fundamental reactivity and transformation of alkyl–gold(0) species.
Molecular-level freezing and melting dynamics of aqueous lithium chloride solutions using in-situ Raman spectroscopy
Modulating the Electron Mediators for Spatially Separated H <sub>2</sub> and O <sub>2</sub> Evolutions in Photocatalytic Water Splitting
ABSTRACT A fundamental obstacle in photocatalytic overall water splitting lies in the simultaneous evolution of H 2 and O 2 gases, which complicates gas separation. Decoupling hydrogen and oxygen evolution via a redox electron mediator offers an attractive route to overcome this limitation; however, its success critically depends on the development of electron mediators that satisfy both suitable redox potentials and rapid interfacial charge‐transfer kinetics. Here, we demonstrate tunable redox potential in cobalt bipyridine complexes, [Co(bpy) 2 Cl 2 ]Cl, through ligand functionalization. Electron‐donating groups (‐OCH 3 , ‐CH 3 ) induce negative shifts in the redox potential, whereas electron‐withdrawing substituents (‐Cl) leads to positive shifts, yielding a broad potential range from 0.15 to 0.62 V versus NHE. The optimized electron mediator, [Co(bpy‐CH 3 ) 2 Cl 2 ]Cl, exhibits enhanced electron transfer and water oxidation activity on BiVO 4 photocatalyst. Coupled with selective assembling of Pt on the electron‐rich {010} facets, an Pt‐Cl interfacial charge‐transfer channel was established, which accelerates electron transfer and promotes the adsorption/desorption of electron mediator. This integrated system achieves efficient photocatalytic water oxidation with an apparent quantum efficiency of up to 90% at 420 nm. Using [Co(bpy‐CH 3 ) 2 Cl 2 ]Cl electron mediator, the work demonstrated the spatial separation of hydrogen and oxygen evolution reactions in particulate photocatalytic water splitting.
Atmospheric kraft pulping in glycerol
Abstract Kraft pulping is the predominant technique for producing chemical pulps from wood. It offers low operational costs, versatility, high-quality pulps, and an efficient closed chemical recovery system. However, the process requires significant investment due to the necessity for pressurized environments and the associated costly equipment. This study explores a novel approach by replacing water with glycerol, allowing kraft pulping to occur at atmospheric pressure. However, the higher viscosity of glycerol compared to water partially limits impregnation. This research investigates the impact of temperature, chemical charge, and chip size on this process for both hardwood and softwood sapwood. The results indicate that lignin dissolution is expedited by reducing chip size for both softwood and hardwood. However, decreasing the chemical charge negatively impacts lignin dissolution. Conversely, increasing the temperature accelerates lignin release.