In Situ Species Analysis of a Lithium-Ion Battery Electrolyte Containing LiTFSI and Propylene Carbonate.

In this study, we analyzed the species in a model electrolyte consisting of a lithium salt, lithium bis(trifluoromethane sulfone)imide (LiTFSI), and a widely used neutral solvent propylene carbonate (PC) with excess infrared (IR) spectroscopy, ab initio molecular dynamics simulations (AIMD), and quantum chemical calculations. Complexing species including the charged ones [Li+(PC)4, TFSI-, TFSI-(PC), TFSI-(PC)2, and Li(TFSI)2-] are identified in the electrolyte. Quantum chemical calculations show strong Li+···O(PC) interaction, which suggests that Li+ would transport in the mode of solvation-carriage. However, the interaction energy of each hydrogen bond in TFSI-(PC) is very weak, suggesting that TFSI- would transport in hopping mode. In addition, the concentration dependences of the relative population of the species were also derived, providing a scenario for the dissolving process of the salt in PC. These in-depth studies provide physical insights into the structural and interactive properties of the electrolyte of lithium-ion batteries.

Atovaquone enhances antitumor efficacy of TCR-T therapy by augmentation of ROS-induced ferroptosis in hepatocellular carcinoma.

T-cell receptor (TCR) engineered T-cell therapy has recently emerged as a promising adoptive immunotherapy approach for tumor treatment, yet hindered by tumor immune evasion resulting in poor therapeutic efficacy. The introduction of ferroptosis-targeted inducers offers a potential solution, as they empower T cells to induce ferroptosis and exert influence over the tumor microenvironment. Atovaquone (ATO) stands as a prospective pharmaceutical candidate with the potential to target ferroptosis, effectively provoking an excessive generation and accumulation of reactive oxygen species (ROS). In this study, we evaluated the effectiveness of a combination therapy comprising ATO and TCR-T cells against hepatocellular carcinoma (HCC), both in vitro and in vivo. The results of lactate dehydrogenase and cytokine assays demonstrated that ATO enhanced cytotoxicity mediated by AFP-specific TCR-T cells and promoted the release of IFN-γ in vitro. Additionally, in an established HCC xenograft mouse model, the combined therapy with low-dose ATO and TCR-T cells exhibited heightened efficacy in suppressing tumor growth, with no apparent adverse effects, comparable to the results achieved through monotherapy. The RNA-seq data unveiled a significant activation of the ferroptosis-related pathway in the combination therapy group in comparison to the TCR-T cells group. Mechanistically, the synergy between ATO and TCR-T cells augmented the release of IFN-γ by TCR-T cells, while concurrently elevating the intracellular and mitochondrial levels of ROS, expanding the labile iron pool, and impairing the integrity of the mitochondrial membrane in HepG2 cells. This multifaceted interaction culminated in the potentiation of ferroptosis within the tumor, primarily induced by an excess of ROS. In summary, the co-administration of ATO and TCR-T cells in HCC exhibited heightened vulnerability to ferroptosis. This heightened susceptibility led to the inhibition of tumor growth and the stimulation of an anti-tumor immune response. These findings suggest that repurposing atovaquone for adoptive cell therapy combination therapy holds the potential to enhance treatment outcomes in HCC.

Spectroscopic and Computational Study of ZnCl2-Methanol Low-Melting-Temperature Mixtures.

Alcoholic electrolyte mixtures have wide applications in industries. In this study, a series of mixtures composed of ZnCl2 and methanol (MeOH) with ZnCl2 mol % from 6.7 to 25 were prepared, and their spectral, structural, and thermodynamic properties were studied using infrared (IR) spectroscopy, differential scanning calorimetry (DSC), and density functional theory (DFT) calculations. The DFT-assisted analysis of excess spectra, supported by 2D-correlation spectroscopy, led to the identification of the major constituents of ZnCl2-MeOH mixtures, namely, MeOH monomer, MeOH dimer, and ZnCl2-3MeOH complex, produced after dissociation of MeOH trimer which represents the bulk methanol. The Hirshfeld charge analysis showed that in the competition between the O-H···Cl hydrogen bond (H-bond) and Zn ← O coordination bond to transfer charge in ZnCl2-MeOH complexes, the latter always dominates, making MeOH positively charged. The phase diagram of the binary system showed the presence of V-shaped glass transition temperatures (Tg), characteristic of low-melting mixture solvents (LoMMSs). The present study provides insights into the microscopic properties of the system and sheds light on the understanding of the general principles to prepare deep-eutectic solvents (DESs) or LoMMSs using inorganic salts and alcoholic compounds.

A Novel Strategy for the Characterization of Self-Assembled Structures Using the Static Solid-State Phosphorus Nuclear Magnetic Resonance Technique.

Structural characterization of assemblies in solutions is essential for understanding the relationship between the structure and material properties. In this study, we introduce a novel approach to investigate amphiphilic self-assemblies in solutions using the phospholipid molecule 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine (Lyso PC) as a 31P NMR probe. The high natural abundance and gyromagnetic ratio of 31P make it one of the most sensitive nuclei in the low-frequency region, enabling efficient detection even in dilute solutions. Lyso PC can readily co-assemble with amphiphilic molecules and ions in aqueous solutions, forming various structures, such as hexagonal, lamellar, and micellar assemblies. The characteristic line shapes of these assemblies reflect the chemical environment around the probe and provide insights into the different phase states of the assemblies. This strategy offers a simple, cost-effective, and static method for obtaining structural information about various assemblies. Our work not only introduces a sensitive probe for characterizing assemblies in a solvent environment but also inspires new ideas for the development of similar spectroscopic probes.

Strong Electron Transfer in Covalently Integrating Cu(I)-Organic Frameworks Enabling Effective Radionuclide Capture.

Rational construction of strong electron-transfer materials remains a challenging task. Herein, we show a design rule for the construction of strong electron-transfer materials through covalently integrating electron-donoring Cu(I) clusters and electron-withdrawing triazine monomers together. As expected, Cu-CTF-1 (Cu(I)-triazine framework) was found to enable strong electron transfer up to 0.46|e| from each Cu(I) metal center to each adjacent triazine fragment. This finally leads to good spatial separation in both photogenerated electron-hole pairs and function units for photocatalytic uranium reduction under ambience and no sacrificial agent and to good charge separation of [I+][I5-] for I2 immobilization under extremely rigorous conditions. The results have not only opened up a structural design principle to access electron-transfer materials but also solved several challenging tasks in the field of radionuclide capture and CTFs.

Fatigue Reliability Assessment of RC Beams in Heavy-Haul Railways Based on Point Estimate Method.

Heavy-haul railways have a high passing frequency of trains with a large axle weight, causing rapid accumulation of fatigue damage in reinforced concrete (RC) bridge structures, which significantly affects the safety of the bridges. To study the fatigue reliability of RC beams in heavy-haul railways, the fatigue performance function for RC beams in heavy-haul railways was established, and the fatigue reliability assessment method for bridge structures in heavy-haul railways based on the point estimate method (PEM) was developed. An 8 meter-span plate beam in an existing heavy-haul railway illustrates the method. The train axle weight and dynamic coefficient were considered random variables, and the first four moments of equivalent stress ranges were obtained. The traffic quantity of the heavy-haul railways was investigated, and the fatigue reliability was evaluated using the proposed method. In addition, the effects of annual freight volume and train axle weight on fatigue reliability were discussed. Results indicate that PEM can effectively and accurately evaluate the fatigue reliability of RC beams in heavy-haul railways. In the first 20 years of operation, the fatigue failure probability was less than the limit value specified in the standard. The increase in annual traffic volume and train axle weight will cause a significant increase in fatigue failure probability. The research results of this paper are expected to provide an important basis for the design and maintenance of reinforced concrete bridges for heavy-haul railways in the future.

Influence of Reflective Coating on Temperature Field and Temperature Effect of CRTS III Slab Ballastless Tracks on Bridges.

To minimize the adverse effects of high temperatures on the service performance of track structures, research on the application of reflective coatings on track structures is urgently needed. Based on meteorological data and the characteristics of the multi-layer structure of the ballastless track, refined finite element models (FEMs) for the temperature field and temperature effect analysis of the CRTS III slab ballastless track structure on bridges were established. The temperature deformation characteristics and temperature stress distribution of the CRTS III slab ballastless track under natural environmental conditions were investigated. Similarly, the influence of a reflective coating on the structural temperature field and temperature effect was studied. The results showed that the temperature and vertical temperature gradient of the track slab were significantly reduced after the application of the reflective coating. Meanwhile, the thermal deformation and thermal stresses of the track slab and the self-compacting concrete (SCC) layer were minimized. Under high-temperature conditions in summer, the maximum temperature of the track slab decreased from 47.0 °C to 39.6 °C after the application of the reflective coating, and the maximum vertical temperature gradient of the track slab decreased from 61.5 °C/m to 39.1 °C/m after the application of the reflective coating. Under the maximum positive temperature gradient, the peak displacement of the upper arch in the middle of the slab and the peak displacement of the sinking in the slab corner decreased from 0.814 mm and 1.240 mm to 0.441 mm and 0.511 mm, respectively, and the maximum transverse tensile stresses of the track slab reduced from 2.7 MPa to 1.5 MPa as well. In addition, the reflective coating could also inhibit the failure of the interlayer interface effectively. The results of this study can provide a theoretical basis and reference for the application of reflective coatings on ballastless tracks on bridges.

Transition Mechanism from the Metastable Two-Dimensional Gel to the Stable Three-Dimensional Crystal of Imidazolium-Based Ionic Liquids.

One important quest for making high quality materials with amphiphiles is to understand how a disordered self-assembly changes to a stable crystalline state. Herein, we addressed the basic question by investigating the phase transition mechanism of imidazolium-based ionic liquid (IL) [C16mim]Br, using time-resolved small- and wide-angle X-ray scattering (SAXS-WAXS), differential scanning calorimetry, and Fourier transform infrared spectroscopy techniques. Totally, a hexagonal phase, two lamellar-gel phases, and three lamellar-crystalline phases were observed, showing the special polymorphism of the system. It was demonstrated that at low concentrations the two-dimensional gel phase (Lß1) transforms into the most stable lamellar-crystal phase (Lc3) through two intermediate crystalline phases Lc1 and Lc2. At high concentrations, the Lß1 phase changes to a condensed lamellar gel phase (Lß2) before changing to Lc2 and eventually to Lc3. Comparative studies using [C16mim]Cl and [C16mim]NO3 unveiled that the interactions between the counterions and the headgroups of the IL, as well as the dehydration process, govern the nucleation process of Lc3 and thus the formation of the crystal. The in-depth investigation on the transition mechanism and the phase polymorphism in the present work advances our understanding of the crystallization of amphiphilic ionic liquids in dispersions and would promote future applications.

Twisting, untwisting, and retwisting of elastic Co-based nanohelices.

The reversible transformation of a nanohelix is one of the most exquisite and important phenomena in nature. However, nanomaterials usually fail to twist into helical crystals. Considering the irreversibility of the previously studied twisting forces, the reverse process (untwisting) is more difficult to achieve, let alone the retwisting of the untwisted crystalline nanohelices. Herein, we report a new reciprocal effect between molecular geometry and crystal structure which triggers a twisting-untwisting-retwisting cycle for tri-cobalt salicylate hydroxide hexahydrate. The twisting force stems from competition between the condensation reaction and stacking process, different from the previously reported twisting mechanisms. The resulting distinct nanohelices give rise to unusual structure elasticity, as reflected in the reversible change of crystal lattice parameters and the mutual transformation between the nanowires and nanohelices. This study proposes a fresh concept for designing reversible processes and brings a new perspective in crystallography.

Neutral MOF Anion Receptor: Radical-Promoted Precise Anion Recognition.

Precise ion recognition plays a key role in the anionic decontamination in water. However, the established anionic recognition based on neutral or cationic anion receptor is still restricted by the inherent limitation, such as narrow application scope in organic solvent rather than water for neutral anion receptor and poor selectivity due to non-directional electrostatic interaction for cationic anion receptor. Herein, for the first time, a neutral metal-organic framework (MOF) anion receptor is shown, enabling precise anion recognition, for example, the presence of a variety of 1000-fold competitive anions does not affect the selective adsorption of the target anion at all. A radical-dominating anion-recognition mechanism is proposed for rationalizing the efficacy of the neutral MOF.

Stochastic resonance analysis of a coupled high-speed maglev vehicle-bridge coupled system under bounded noise.

Coupled oscillations typically occur in maglev vehicle-bridge coupled systems excited by bounded noise caused by guideway irregularities. The paper employed Hamilton equations to derive the corresponding canonical transformation equations and determined the critical stable regions for two kinds of resonances using the largest Lyapunov exponents. The results show that the critical stable region between the excitation amplitude and the resonant frequency ratio is a valley shape when the system has external resonance only. When considering both internal and external resonances, the critical stable region between the excitation amplitude and resonant frequency ratio presents a small saddle shape. Energy transfers from the first to the second oscillator under with both internal and extrinsic resonance. As the guideway irregularities' coefficients increase, the maximum Lyapunov exponents of the two conditions change from negative to positive, which means that the system varies from a stable state to instability.

Experimental Investigation of Seismic Performance of Precast Concrete Wall-Beam-Slab Joints with Overlapping U-Bar Loop Connections.

In the era of energy conservation and environmental protection, as well as the industrialization of buildings, precast concrete (PC) structures have been developed and increasingly applied in construction industries due to their advantages of outstanding workability and ecofriendliness. In order to verify the reliability of overlapping U-bar loop connections and a modified form of these connections, and study the seismic performance of PC wall-beam-slab joints with these connection methods, three full-scale wall-beam-slab joints were designed and tested under low reversed cyclic loading, including one cast-in-place (CIP) specimen and two PC specimens. Based on the test results, the seismic performance of the PC joints was studied by comparing their damage process, hysteretic loops and skeleton curves, load-carrying capacity, ductility, equivalent stiffness, and energy dissipation with those of the CIP joint. After analyzing the experimental results, the following conclusions can be drawn: the overlapping U-bar loop connection and its modified form are effective and reasonable; the specimen with the modified connection form showed slightly better mechanical properties; the failure mode of the PC joints was consistent with that of the CIP joint; and the generation, distribution, and development of cracks in the PC specimens were similar to those in the CIP specimen. In addition, the stiffness of the PC joints was similar to that of the CIP joint, and the load-carrying capacity, ductility, and energy dissipation of the PC joints were better than those of the CIP joint. Moreover, the research in this paper can also provide some guidance for assembling wall-beam-slab joints in PC shear wall structures.

Experimental Study on the Influence of Transverse Crack on Chloride Ingress in Concrete Slab Track of High-Speed Railway.

The concrete track slab and the base slab of the high-speed railway CRTS II track structure are prone to transverse cracks in the initial service period, which are subjected to environmental action and train load. In order to investigate the influence of transverse cracks on chloride ingress of concrete track slab and base slab in a coastal environment, drying-wetting cycle chloride erosion tests were carried out on reinforced concrete track slab and base slab specimens with cracks ranging from 0 mm to 0.6 mm, subjected to continuous bending moment. The chloride ion concentration of concrete along the depth direction was collected during the test process. The experimental results show that the chloride ion concentration of concrete at the crack section is much higher than that at the intact section, and it increases with the increase of crack width in the range of 0.2 mm to 0.6 mm. A chloride diffusion coefficient model of cracked concrete is proposed for slab track based on the experimental results, which can comprehensively consider the effects of surface chloride ion concentration, chloride binding effect, time-varying effect, temperature, relative humidity, and transverse crack width.

Sulfonic-Pendent Vinylene-Linked Covalent Organic Frameworks Enabling Benchmark Potential in Advanced Energy.

Both proton exchange membrane fuel cells and uranium-based nuclear techniques represent two green and advanced energies. However, both of them still face some intractable scientific and industrial problems. For the former, established proton-conduction materials always suffer one or another defect such as low proton conductivity, high activation energy, bad durability, or just small-scale product; while for the later, there still lacks available adsorbent to selectively recover of UO2 2+ from concentrated nitric acid (>1 M) during the spent fuel reprocessing due to the deactivation of the adsorption site or the decomposition of adsorbent under such rigorous conditions. It is found that the above two issues can be well solved by the construction of sulfonic-pendent vinylene-linked covalent organic frameworks (COFs), since these COFs contain abundant sulfonic units for both intrinsic proton conduction and UO2 2+ capture through strong coordination fixation and vinylene linkage that enhances the stability up to 12 M nitric acid (one of the best materials surviving in 12 M HNO3 ).

Free-Standing Two-Dimensional Crystals Formed from Self-Assembled Ionic Liquids.

The fabrication of two-dimensional crystals (2DCs) has attracted very large interest because it creates materials with various surface structural features and special surface properties. Normally, this is limited to sheets networked together with strong covalent or coordination bonds. Against this understanding, we discovered macroscopic scale free-standing 2DCs in the aqueous dispersions of [Cnmim]X (X = Br, NO3; n = 14, 16, 18) using simultaneous synchrotron small- and wide-angle X-ray scattering techniques. On the other hand, the 2DCs are also a kind of novel hydrogel holding water content up to 98 wt %. This unusual phenomenon is attributed to the weak interactions between imidazole headgroups and counterions. The observation reported in this work is expected to contribute to theorists in their pursuit of the general principles governing the stability of 2D materials. It may also enlighten experimentalists in designing new free-standing 2DCs for various applications.

A Static Damage Constitutive Model of Concrete Based on Microscopic Damage Mechanism.

In this article, a microscopic constitutive model is established that includes friction, plastic, and spring elements and has clear physical meaning. The friction unit reflects the mutual friction between crack surfaces, the plastic unit reflects the development of concrete plasticity, and the fracture of the spring unit reflects the formation and expansion of interior cracks in concrete. In addition, the integration of the random field theory into this model uncovers the physical underpinnings of the relationship between concrete's nonlinearity and randomness. The multi-scale modeling of the concrete static damage constitutive model is then realized once the parameters of the random field are discovered using the macro test results. In order to apply the model's applicability in finite element programs, a subroutine was ultimately constructed. The experimental data and the anticipated values from the numerical simulation are in good agreement, supporting the model's realism.

Unveiling the Surface Structure of ZnO Nanorods and H2 Activation Mechanisms with 17O NMR Spectroscopy.

ZnO plays a very important role in many catalytic processes involving H2, yet the details on their interactions and H2 activation mechanism are still missing, owing to the lack of a characterization method that provides resolution at the atomic scale and follows the fate of oxide surface species. Here, we apply 17O solid-state NMR spectroscopy in combination with DFT calculations to unravel the surface structure of ZnO nanorods and explore the H2 activation process. We show that six different types of oxygen ions in the surface and subsurface of ZnO can be distinguished. H2 undergoes heterolytic dissociation on three-coordinated surface zinc and oxygen ions, while the formed hydride species migrate to nearby oxygen species, generating a second hydroxyl site. When oxygen vacancies are present, homolytic dissociation of H2 occurs and zinc hydride species form from the vacancies. Reaction mechanisms on oxide surfaces can be explored in a similar manner.

Abnormalities of the Halogen Bonds in the Complexes between Y2CTe (Y = H, F, CH3) and XF (X = F, Cl, Br, I).

In this work, the hydrogen bonds and halogen bonds in the complexes between Y2CTe (Y = H, F, CH3) and XF (X = F, Cl, Br, I) have been studied by quantum chemical calculations. We found three interesting abnormalities regarding the interactions. Firstly, the strength of halogen bonds increases in the order of IF < BrF < ClF < F2. Secondly, the halogen bonds formed by F2 are very strong, with an interaction energy in the range between −199.8 and −233.1 kJ/mol. Thirdly, all the halogen bonds are stronger than the hydrogen bonds in the systems we examined. All these results are against the general understanding of halogen bonds. These apparent abnormal properties are reconciled with the high polarizability of the Te atom and the strong inducing effect of F on the Te atom of Y2CTe. These findings provide a new perspective on halogen bonds. Additionally, we also proposed bonding distance-based methods to compare the strength of halogen/hydrogen bonds formed between different donor atoms and the same acceptor atom.

Fatigue Performance Prediction of RC Beams Based on Optimized Machine Learning Technology.

The development of fatigue damage in reinforced concrete (RC) beams is affected by various factors such as repetitive loads and material properties, and there exists a complex nonlinear mapping relationship between their fatigue performance and each factor. To this end, a fatigue performance prediction model for RC beams was proposed based on the deep belief network (DBN) optimized by particle swarm optimization (PSO). The original database of fatigue loading tests was established by conducting fatigue loading tests on RC beams. The mid-span deflection, reinforcement strain, and concrete strain during fatigue loading of RC beams were predicted and evaluated. The fatigue performance prediction results of the RC beam based on the PSO-DBN model were compared with those of the single DBN model and the BP model. The models were evaluated using the R2 coefficient, mean absolute percentage error, mean absolute error, and root mean square error. The results showed that the fatigue performance prediction model of RC beams based on PSO-DBN is more accurate and efficient.

Cholesterol Protects the Liquid-Ordered Phase of Raft Model Membranes from the Destructive Effect of Ionic Liquids.

Ionic liquids (ILs), although being a class of promising green solvents, have received many reports on the toxicity to living organisms. In this work, aiming at elucidating the disruptive effect of ILs to cell membrane lipid rafts, we investigated the effect of three 1-octylimidazolium-based ILs on the properties of the liquid ordered phase (Lo, a commonly used lipid raft model) of egg sphingomyelin (SM)-cholesterol model membrane. We found that, in the absence of cholesterol, a very low IL:SM molar ratio of 0.01:1 could disrupt the integrity of the bilayer structure. In sharp contrast, the presence of cholesterol in lipid bilayers helps the Lo phase resist the damaging effect of the ILs. For the role of the IL headgroup, we found that the mono- and trisubstituted species show a stronger destructive effect on the structures of the model rafts than the commonly used disubstituted counterpart.