Electrocatalytic water splitting for the production of H2 is increasingly becoming a significant method to mitigate the current energy crisis and environmental pollution. However, oxygen evolution ...reaction (OER), a slow four-electron progress, is the bottle neck of water splitting. Thus, developing new, low cost, and effective catalysts for OER is a research hotspot in material and energy resource fields. Therefore, the research of nonprecious, metal-based OER catalysts has been popular. In this work, it is validated that 3D hollow Co(OH)2 nanoflowers synthesized by a facile template-based strategy at room temperature are effective electrocatalysts for OER. The catalysts display high activity with a current density of 10 mA/cm2 at an overpotential of 310 mV and a small Tafel slope of 68.9 mV/dec in alkaline condition. It’s noteworthy that this material is stable for over 20 h of chronopotentiometry. This work offers a simple and promising way to prepare efficient and durable electrocatalysts.
The Malan loess is a greyish yellow unstratified sediment with uniform lithology, large pores and loose texture. The Malan loess is sensitive to water due to its porous and metastable structure. ...Water‐induced disintegration is the main cause of soil loss in the Loess Plateau of China and the primary evolutionary driving force of the loess landform. A series of laboratory tests is conducted on undisturbed cylindrical Malan loess samples to understand their disintegration behaviour further and examine potential influencing factors. Results show that the Malan loess experiences primary and secondary disintegration stages. The primary disintegration occurs very fast and terminates in an average of 40 s. Approximately 78% of the soil disintegrates in this stage. The disintegration velocity (V) and percentage (Df) in the primary stage demonstrate high correlation with the dry density, clay mineral content and CaCO3 content. Specifically, Df increases while V decreases with the increase of dry density or clay content. Df decreases while V increases with the increase of CaCO3. The concentration of ions, including Cl−, SO42−, CO32−, HCO3−, Ca2+, K+, Na+ and Mg2+, and the organic matter content do not exhibit a clear relationship with Df and V. In addition, the pore structure influences the Malan loess disintegration. The soil with evenly distributed small pores is subjected to gradual disintegration from outside to inside without abrupt failure, while that with large pipes disintegrates abruptly in large pieces.
The Malan loess with evenly distributed small pores gradually disintegrates from outside to inside without abrupt failure, and that with large pipes disintegrates in large pieces and presents an abrupt disintegration at one moment.
Ultrafine nanoparticles with organic–inorganic hybridization have essential roles in myriad applications. Over the past three decades, although various efforts on the formation of organic or ...inorganic ultrasmall nanoparticles have been made, ultrafine organic–inorganic hybrid nanoparticles have scarcely been achieved. Herein, a family of ultrasmall hybrid nanoparticles with a monodisperse, uniform size is synthesized by a facile thermo‐kinetics‐mediated copolymer monomicelle approach. These thermo‐kinetics‐mediated monomicelles with amphiphilic ABC triblock copolymers are structurally robust due to their solidified polystyrene core, endowing them with ultrahigh thermodynamic stability, which is difficult to achieve using Pluronic surfactant‐based micelles (e.g., F127). This great stability combined with a core–shell–corona structure makes the monodispersed monomicelles a robust template for the precise synthesis of ultrasmall hybrid nanoparticles with a highly uniform size. As a demonstration, the obtained micelles/SiO2 hybrid nanoparticles display ultrafine sizes, excellent uniformity, monodispersity, and tunable structural parameters (diameters: 24–47 nm and thin shell thickness: 2.0–4.0 nm). Notably, this approach is universal for creating a variety of multifunctional ultrasmall hybrid nanostructures, involving organic/organic micelle/polymers (polydopamine) nanoparticles, organic/inorganic micelle/metal oxides (ZnO, TiO2, Fe2O3), micelle/hydroxides (Co(OH)2), micelle/noble metals (Ag), and micelle/TiO2/SiO2 hybrid composites. As a proof of concept, the ultrasmall micelle/SiO2 hybrid nanoparticles demonstrate superior toughness as biomimetic materials.
A library of ultrasmall hybrid nanoparticles with great uniformity, monodispersity, and tunable shell thickness is successfully synthesized by a facile thermo‐kinetics‐mediated copolymer monomicelle approach. This monomicelle with a solidified polystyrene core has ultrahigh thermodynamic stability. Combined with a unique core–shell–corona structure, this monomicelle is a very general template to synthesize various ultrasmall, monodispersed hybrid nanoparticles with excellent uniformity.
An aqueous emulsion polymerization self‐assembly approach is demonstrated for the first time to synthesize ultrahigh nitrogen containing mesoporous polymer nanospheres, using melamine‐formaldehyde ...resin oligomers as precursors. In the synthesis, change from alkaline to acidic conditions is critical for the formation of monodisperse mesostructured polymer nanospheres. Owing to unique structure of triazine stabilized in the covalent polymeric networks during the pyrolysis process, the derived mesoporous carbon nanospheres possess an ultrahigh nitrogen content (up to 15.6 wt%) even after pyrolysis at 800 °C, which is the highest nitrogen content among mesoporous carbon nanospheres. Furthermore, these monodisperse mesoporous carbon nanospheres possess a high surface area (≈883 m2 g−1) and large pore size (≈8.1 nm). As an anode for sodium‐ion batteries, the ultrahigh nitrogen‐containing mesoporous carbon nanospheres exhibit superior rate capability (117 mAh g−1 at a high current density of 3 A g−1) and high reversible capacity (373 mAh g−1 at 0.06 A g−1), indicating a promising material for energy storage.
Monodisperse mesoporous carbon nanospheres are synthesized by an aqueous emulsion polymerization self‐assembly strategy. The step process from alkaline to acidic condition is the key for the synthesis. The mesoporous carbon nanospheres possess an ultrahigh nitrogen content (15.6 wt%), tunable diameters (≈20–80 nm), and large pore sizes (≈6.7–8.1 nm).
Highly crystallized mesoporous TiO2/WO3 heterojunctions was synthesized via a novel “acid-base pair” strategy for acetone gas sensing.
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Mesoporous semiconducting metal oxides (SMOs) ...heterojunctions are appealing sensors for gas detecting. However, due to the different hydrolysis and condensation mechanism of every metal precursor and the contradiction between high crystallinity and high surface area, the synthesis of mesoporous SMOs heterojunctions with highly ordered mesostructures, highly crystallized frameworks, and high surface area remains a huge challenge. In this work, we develop a novel “acid-base pair” adjusted solvent evaporation induced self-assembly (EISA) strategy to prepare highly crystallized ordered mesoporous TiO2/WO3 (OM-TiO2/WO3) heterojunctions. The WCl6 and titanium isopropoxide (TIPO) are used as the precursors, respectively, which function as the “acid-base pair”, enabling the co-assembly with the structure directing agent (PEO-b-PS) into highly ordered mesostructures. In addition, PEO-b-PS can be converted to rigid carbon which can protect the mesostructures from collapse during the crystallization process. The resultant OM-TiO2/WO3 heterojunctions possess primitive cubic mesostructures, large pore size (∼21.1 nm), highly crystalline frameworks and surface area (∼98 m2/g). As a sensor for acetone, the obtained OM-TiO2/WO3 show excellent response/recovery performance (3 s/5 s), good linear dependence, repeatability, selectivity, and long-term stability (35 days).
Diabetes is a type of metabolic disease associated with changes in the intestinal flora. In this study, the regulatory effect of millet bran on intestinal microbiota in a model of type 2 diabetes ...(T2DM) was investigated in an effort to develop new approaches to prevent and treat diabetes and its complications in patients. The effect of purified millet bran polysaccharide (MBP) with three different intragastric doses (400 mg/kg, 200 mg/kg, and 100 mg/kg) combined with a high-fat diet was determined in a streptozotocin (STZ)-induced model of T2DM. By analyzing the changes in indicators, weight, fasting blood sugar, and other bio-physiological parameters, the changes in gut microbiota were analyzed via high-throughput sequencing to establish the effect of MBP on the intestinal flora. The results showed that MBP alleviated symptoms of high-fat diet-induced T2DM. A high dosage of MBP enhanced the hypoglycemic effects compared with low and medium dosages. During gavage, the fasting blood glucose (FBG) levels of rats in the MBP group were significantly reduced (p < 0.05). The glucose tolerance of rats in the MBP group was significantly improved (p < 0.05). In diabetic mice, MBP significantly increased the activities of CAT, SOD, and GSH-Px. The inflammatory symptoms of liver cells and islet cells in the MBP group were alleviated, and the anti-inflammatory effect was partially correlated with the dose of MBP. After 4 weeks of treatment with MBP, the indices of blood lipid in the MBP group were significantly improved compared with those of the DM group (p < 0.05). Treatment with MBP (400 mg/kg) increases the levels of beneficial bacteria and decreases harmful bacteria in the intestinal tract of rats, thus altering the intestinal microbial community and antidiabetic effect on mice with T2DM by modulating gut microbiota. The findings suggest that MBP is a potential pharmaceutical supplement for preventing and treating diabetes.
Flexible pressure sensors employing porous polymer materials are renowned for their superior sensing capabilities, attributed to the inherently low stiffness of porous polymers. The practical ...utilization of such sensors hinges on the development of a straightforward, cost‐effective, and patternable method for preparing porous polymer materials. In this research, a novel laser thermoforming process is introduced to craft a porous Polydimethylsiloxane (PDMS) film, leveraging carbon black (CB) as an endothermic agent and glucose as a porogen. The resulting porous PDMS film serves as the foundation for a remarkably sensitive flexible piezoresistive sensor. Owing to the inherent flexibility endowed by the porous structure, the porous PDMS‐based pressure sensor achieves a remarkable sensitivity of 109.4 kPa−1 within 0–200 Pa, an effective measurement span of 0–100 kPa, rapid response and recovery times of 79 and 55 ms, and impressive stability over 5000 cycles. The sensor's utility extends to applications such as human pulse monitoring, Morse coding, and robot claw sensing, underscoring its promise in the realm of flexible electronics. In summary, the laser thermoforming process realizes the one‐step, economical, and patternable preparation of porous polymer materials, and introduces a novel avenue for the realization of high‐performance flexible sensors based on thermally cured porous polymers.
A facile, patternable, and efficient laser thermoforming process, wherein an infrared laser is deployed to irradiate a PDMS precursor infused with carbon black and glucose monohydrate, is proposed for the preparation of a porous PDMS film. The resulting porous PDMS film serves as the foundation for a remarkably sensitive flexible piezoresistive sensor for health monitoring and soft robot.
Copper (Cu) removal efficiency is a key parameter in the processing of Cu-based electronic devices. Herein, a nitrogen plasma-assisted picosecond (ps) laser process for Cu removal is presented. Based ...on the cleaning and activation effect of nitrogen plasma on the surface of Cu film in ps-laser ablation, the removal efficiency can be significantly improved. Theoretically, the interaction mechanism between Cu and the ps-laser under the action of the plasma flow field is investigated by the dual temperature model (TTM) and finite element analysis (FEA). Meanwhile, the experimental results show that the angle of the plasma flow significantly affects the laser ablation of Cu. Small-angle plasma helps to improve the ps-laser processing precision of Cu, while large-angle plasma can effectively improve the ps-laser processing efficiency of Cu. Under the laser fluence of 2.69 J/cm2, the removal depth of the Cu film by a 30° plasma-assisted ps-laser is 148% higher than that by the non-plasma-assisted ps-laser, which indicates the application potential of nitrogen plasma in improving the laser ablation process.
Lysosomal pH plays indispensable roles in regulating the activity of lysosomal hydrolases, and is involved in crucial biological procedures including autophagy. Fluorescent probes for lysosomal pH ...were significant molecular tools to investigate lysosomal pH regulation. In this work, we have designed a new fluorophore to respond to pH in a ratiometric manner based on intramolecular charge transfer (ICT) mechanism. By modifying different alkyl chains on the dye, we have obtained a novel ratiometric probe for lysosomal pH with optimized membrane permeability. The probe could stain lysosomes, and was capable of monitoring lysosomal pH in a ratiometric manner. Chloroquine (CQ) induced pH rise in lysosomes was successfully visualized with the probe. The down-regulation and subsequence up-regulation of lysosomal pH during starvation were also revealed in ratiometric manner. We firmly believe that the probe is a desirable tool to investigate lysosomal pH and promote the studies in autophagy and relative biological areas.
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•A novel fluorophore responding to pH in a ratiometric manner was designed using intramolecular charge transfer mechanism.•A fluorescent probe for lysosomal pH with optimized membrane permeability was obtained.•The down-regulation and subsequence up-regulation of lysosomal pH during starvation were revealed in the ratiometric manner.
The slow kinetics of water oxidation greatly jeopardizes the efficiency of water electrolysis for H2 production. Developing highly active water oxidation electrodes with affordable fabrication costs ...is thus of great importance. Herein, a NiIIFeIII surface species on Ni metal substrate was generated by electrochemical modification of Ni in a ferrous solution by a fast, simple, and cost‐effective procedure. In the prepared NiIIFeIII catalyst film, FeIII was incorporated uniformly through controlled oxidation of FeII cations on the electrode surface. The catalytically active NiII originated from the Ni foam substrate, which ensured the close contact between the catalyst and the support toward improved charge‐transfer efficiency. The as‐prepared electrode exhibited high activity and long‐term stability for electrocatalytic water oxidation. The overpotentials required to reach water oxidation current densities of 50, 100, and 500 mA cm−2 are 276, 290, and 329 mV, respectively.
Foam electrodes: A NiFe‐based electrode is fabricated by electrochemical modification of a Ni foam (NF) in a ferrous solution by a fast, simple, and cost‐effective procedure. The NF serves both as a support and source of Ni for the active catalyst. This electrode shows high efficiency and long‐term robustness for electrocatalytic water oxidation in basic aqueous solution.
