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Interfacial charge transfer is widely assumed to obey the Butler–Volmer kinetics. For certain liquid–solid interfaces, the Marcus–Hush–Chidsey theory is more accurate and predictive, but it has not been applied to porous electrodes. Here we report a simple method to extract the charge transfer rates in carbon-coated LiFePO 4 porous electrodes from chronoamperometry experiments, obtaining curved Tafel plots that contradict the Butler–Volmer equation but fit the Marcus–Hush–Chidsey prediction over a range of temperatures. The fitted reorganization energy matches the Born solvation energy for electron transfer from carbon to the iron redox site. The kinetics are thus limited by electron transfer at the solid–solid (carbon-Li x FePO 4 ) interface rather than by ion transfer at the liquid–solid interface, as previously assumed. The proposed experimental method generalizes Chidsey’s method for phase-transforming particles and porous electrodes, and the results show the need to incorporate Marcus kinetics in modelling batteries and other electrochemical systems. Electrochemical kinetics are usually described by the Butler–Volmer equation. Bai and Bazant propose a method to extract reaction rates for porous electrodes from experiments and show the necessity of using Marcus charge transfer theory in place of the conventional kinetics.

The sparse rain gauge networks over the Tibetan Plateau (TP) cause challenges for hydrological studies and applications. Satellite-based precipitation datasets have the potential to overcome the issues of data scarcity caused by sparse rain gauges. However, large uncertainties usually exist in these precipitation datasets, particularly in complex orographic areas, such as the TP. The accuracy of these precipitation products needs to be evaluated before being practically applied. In this study, five (quasi-)global satellite precipitation products were evaluated in two gauge-sparse river basins on the TP during the period 1998–2012; the evaluated products are CHIRPS, CMORPH, PERSIANN-CDR, TMPA 3B42, and MSWEP. The five precipitation products were first intercompared with each other to identify their consistency in depicting the spatial–temporal distribution of precipitation. Then, the accuracy of these products was validated against precipitation observations from 21 rain gauges using a point-to-pixel method. We also investigated the streamflow simulation capacity of these products via a distributed hydrological model. The results indicated that these precipitation products have similar spatial patterns but significantly different precipitation estimates. A point-to-pixel validation indicated that all products cannot efficiently reproduce the daily precipitation observations, with the median Kling–Gupta efficiency (KGE) in the range of 0.10–0.26. Among the five products, MSWEP has the best consistency with the gauge observations (with a median KGE = 0.26), which is thus recommended as the preferred choice for applications among the five satellite precipitation products. However, as model forcing data, all the precipitation products showed a comparable capacity of streamflow simulations and were all able to accurately reproduce the observed streamflow records. The values of the KGE obtained from these precipitation products exceed 0.83 in the upper Yangtze River (UYA) basin and 0.84 in the upper Yellow River (UYE) basin. Thus, evaluation of precipitation products only focusing on the accuracy of streamflow simulations is less meaningful, which will mask the differences between these products. A further attribution analysis indicated that the influences of the different precipitation inputs on the streamflow simulations were largely offset by the parameter calibration, leading to significantly different evaporation and water storage estimates. Therefore, an efficient hydrological evaluation for precipitation products should focus on both streamflow simulations and the simulations of other hydrological variables, such as evaporation and soil moisture.

Solvent selection is a pressing challenge in developing efficient and selective liquid phase catalytic processes, as predictive understanding of the solvent effect remains lacking. In this work, an attenuated total reflection infrared spectroscopy technique is developed to quantitatively measure adsorption isotherms on porous materials in solvent and decouple the thermodynamic contributions of van der Waals interactions within zeolite pore walls from those of pore-phase proton transfer. While both the pore diameter and the solvent identity dramatically impact the confinement (adsorption) step, the solvent identity plays a dominant role in proton-transfer. Combined computational and experimental investigations show increasingly favorable pore-phase proton transfer to pyridine in the order: water < acetonitrile < 1,4 – dioxane. Equilibrium methods unaffected by mass transfer limitations are outlined for quantitatively estimating fundamental thermodynamic values using statistical thermodynamics. Liquid phase reactions mediated by solid catalysts occur in the presence of solvents whose role needs to be understood. The authors use attenuated total reflection infrared spectroscopy to measure liquid-phase pyridine adsorption isotherms in zeolites, elucidating the effect of coadsorbed solvents on the interactions.

Regioselective arene C−H bond alkylation is a powerful tool in synthetic chemistry, yet subject to many challenges. Herein, we report the meta -C−H bond alkylation of aromatics bearing N -directing groups using (hetero)aromatic epoxides as alkylating agents. This method results in complete regioselectivity on both the arene as well as the epoxide coupling partners, cleaving exclusively the benzylic C−O bond. Oxetanes, which are normally unreactive, also participate as alkylating reagents under the reaction conditions. Our mechanistic studies reveal an unexpected reversible epoxide ring opening process undergoing catalyst-controlled regioselection, as key for the observed high regioselectivities. Regioselective arene C−H bond alkylation is a powerful tool in synthetic chemistry, yet subject to many challenges. Here, the authors report the meta-C−H bond alkylation of aromatics bearing N-directing groups using (hetero)aromatic epoxides as alkylating agents.

The characteristics of the degrees of freedom (DOFs) of the 3-UPU parallel mechanisms (PMs) are closely related to the orientations of the ending R joints fixed connected with the platforms. The orientations of the ending revolute (R) joints in the Tsai 3-UPU PM cannot naturally realize three translational DOFs. First, this paper gives and proves the geometric conditions of the ending R joint fixed to the platforms that can naturally ensure three translational DOFs of the 3-UPU PMs. Second, based on the common motion/force index and good transmission workspace volume of the 3-UPU translational PMs, the performance map of the PMs is drawn, and the corresponding optimization design area of the PMs is obtained. Finally, combined with the obtained optimization design area, in view of the differences in the constraint and stiffness performance of the 3-UPU translational PMs, the multi-objective optimization is carried out using the game theory algorithm, and the orientations of the ending R joints for the 3-UPU translational PMs with good constraint and stiffness performance are obtained.

The use of polar aprotic solvents in acid-catalyzed biomass conversion reactions can lead to improved reaction rates and selectivities. We show that further increases in catalyst performance in polar aprotic solvents can be achieved through the addition of inorganic salts, specifically chlorides. Reaction kinetics studies of the Brønsted acid-catalyzed dehydration of fructose to hydroxymethylfurfural (HMF) show that the use of catalytic concentrations of chloride salts leads to a 10-fold increase in reactivity. Furthermore, increased HMF yields can be achieved using polar aprotic solvents mixed with chlorides. Ab initio molecular dynamics simulations (AIMD) show that highly localized negative charge on Cl − allows the chloride anion to more readily approach and stabilize the oxocarbenium ion that forms and the deprotonation transition state. High concentrations of polar aprotic solvents form local hydrophilic environments near the reactive hydroxyl group which stabilize both the proton and chloride anions and promote the dehydration of fructose. Despite the potential advantages of using polar aprotic solvents for biomass upgrading reactions, fundamental understanding of these solvation effects is limited at present. Here, the authors show that further increases in catalyst performance in polar aprotic solvents can be achieved through the addition of inorganic salts.

In this study, a series of Al-doped metal-organic frameworks (AlxZr(1−x)-UiO-66) were synthesized through a one-step solvothermal method. Various characterization techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and N2 sorption measurement, suggested that the Al doping was uniform and barely influenced the crystallinity, chemical stability, and thermal stability of the materials. Two cationic dyes, safranine T (ST) and methylene blue (MB), were selected for investigating the adsorption performances of Al-doped UiO-66 materials. Al0.3Zr0.7-UiO-66 exhibited 9.63 and 5.54 times higher adsorption capacities than UiO-66, 498 mg/g and 251 mg/g for ST and MB, respectively. The improved adsorption performance can be attributed to π-π interaction, hydrogen bond, and the coordination between the dye and Al-doped MOF. The pseudo-second-order and Langmuir models explained the adsorption process well, which indicated that the dye adsorption on Al0.3Zr0.7-UiO-66 mostly occurred through chemisorption on homogeneous surfaces. A thermodynamic study indicated the adsorption process was spontaneous and endothermic. The adsorption capacity did not decrease significantly after four cycles.

Acute internal carotid artery occlusion (AICAO) can result in malignant cerebral edema and unfavorable patient outcomes. This study evaluated the utility of transcranial Doppler (TCD) in assessing contralateral flow compensation and predicting outcomes in patients with AICAO. We enrolled 51 patients within 6 h of symptom onset and conducted TCD examinations to evaluate collateral circulation. Among the 51 patients, 40 (78.4%) had collateral flow. TCD showed excellent agreement with magnetic resonance angiography (MRA)/CT angiography (CTA) in assessing anterior communicating artery (ACoA) status (kappa = 0.873, p  < 0.001). Our findings indicated that the absence of collaterals (OR = 7.649, p  = 0.032), younger age (OR = 0.907, p  = 0.048), and lower Alberta Stroke Program Early CT Score 24 h after onset (ASPECTs1) (OR = 0.276, p  = 0.025) were independent predictors of malignant cerebral edema. Additionally, advanced age, elevated National Institutes of Health Stroke Scale Score (NIHSSs) in the Emergency Department, sole extracranial-to-intracranial collateral circulation (EICC), and absence ACoA were independently associated with worse outcomes (all p  < 0.05). In conclusion, TCD evaluation of collateral circulation in AICAO patients can effectively predict the risk of malignant cerebral edema, with ACoA presence correlating with favorable outcomes and sole EICC linked to poorer prognosis. While age, NIHSSs and ASPECTs also contribute, TCD’s assessment of collaterals provides key insights for patient management.

Triboelectric nanogenerators （TENGs） have been demonstrated as an effective way to harvest mechanical energy to drive small electronics. The density of triboelectric charges generated on contact surfaces between two distinct materials is a critical factor for dictating the output power. We demonstrate an approach to effectively tune the triboelectric properties of materials by taking advantage of the dipole moment in polarized polyvinylidene fluoride （PVDF）, leading to substantial enhancement of the output power density of the TENG. The output voltage ranged from 72 V to 215 V under a constant contact force of 50 N. This work not only provides a new method of enhancing output power of TENGs, but also offers an insight into charge transfer in contact electrification by investigating dipole-moment-induced effects on the electrical output of TENGs.

A direct synthesis of high-aspect-ratio microporous zeolite nanosheets and the use of such nanosheets in separation membranes are described. Ultra-slim zeolite membranes Zeolites—naturally occurring porous crystalline aluminosilicates that are also produced industrially on a large scale—are used commercially as selective adsorbents. Zeolite membranes can be used for selective dehydration, but more general separations, for example of hydrocarbon isomers, are challenging because they require thin membranes with highly oriented pores. At present, such thin membranes are produced by an expensive and low-yielding exfoliation process. Here the authors produce nanometre-thick zeolite nanosheets using a bottom-up seeded growth method that retains the pore structure and avoids rotational intergrowths. Using xylene isomer separation as a benchmark, the authors found that their compact membranes had higher selectivities and flux rates than previous zeolite membranes. A zeolite with structure type MFI 1 , 2 is an aluminosilicate or silicate material that has a three-dimensionally connected pore network, which enables molecular recognition in the size range 0.5–0.6 nm. These micropore dimensions are relevant for many valuable chemical intermediates, and therefore MFI-type zeolites are widely used in the chemical industry as selective catalysts or adsorbents 3 , 4 , 5 . As with all zeolites, strategies to tailor them for specific applications include controlling their crystal size and shape 5 , 6 , 7 , 8 . Nanometre-thick MFI crystals (nanosheets) have been introduced in pillared 9 and self-pillared (intergrown) 10 architectures, offering improved mass-transfer characteristics for certain adsorption and catalysis applications 11 , 12 , 13 , 14 . Moreover, single (non-intergrown and non-layered) nanosheets have been used to prepare thin membranes 15 , 16 that could be used to improve the energy efficiency of separation processes 17 . However, until now, single MFI nanosheets have been prepared using a multi-step approach based on the exfoliation of layered MFI 9 , 15 , followed by centrifugation to remove non-exfoliated particles 18 . This top-down method is time-consuming, costly and low-yield and it produces fragmented nanosheets with submicrometre lateral dimensions. Alternatively, direct (bottom-up) synthesis could produce high-aspect-ratio zeolite nanosheets, with improved yield and at lower cost. Here we use a nanocrystal-seeded growth method triggered by a single rotational intergrowth to synthesize high-aspect-ratio MFI nanosheets with a thickness of 5 nanometres (2.5 unit cells). These high-aspect-ratio nanosheets allow the fabrication of thin and defect-free coatings that effectively cover porous substrates. These coatings can be intergrown to produce high-flux and ultra-selective MFI membranes that compare favourably with other MFI membranes prepared from existing MFI materials (such as exfoliated nanosheets or nanocrystals).